{"id":290,"date":"2021-07-14T15:59:07","date_gmt":"2021-07-14T15:59:07","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/introstatscorequisite\/chapter\/matched-or-paired-samples\/"},"modified":"2023-12-05T09:39:54","modified_gmt":"2023-12-05T09:39:54","slug":"matched-or-paired-samples","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/introstatscorequisite\/chapter\/matched-or-paired-samples\/","title":{"raw":"Hypothesis Testing with Paired Samples","rendered":"Hypothesis Testing with Paired Samples"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<section>\r\n<ul>\r\n \t<li>Conduct a hypothesis test for matched or paired data and interpret the conclusion in context<\/li>\r\n<\/ul>\r\n<\/section><\/div>\r\nWhen using a hypothesis test for matched or paired samples, the following characteristics should be present:\r\n<ol>\r\n \t<li>Simple random sampling is used.<\/li>\r\n \t<li>Sample sizes are often small.<\/li>\r\n \t<li>Two measurements (samples) are drawn from the same pair of individuals or objects.<\/li>\r\n \t<li>Differences are calculated from the matched or paired samples.<\/li>\r\n \t<li>The differences form the sample that is used for the hypothesis test.<\/li>\r\n \t<li>Either the matched pairs have differences that come from a population that is normal or the number of differences is sufficiently large so that distribution of the sample mean of differences is approximately normal.<\/li>\r\n<\/ol>\r\nIn a hypothesis test for matched or paired samples, subjects are matched in pairs, and differences are calculated. The differences are the data. The population mean for the differences, <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em>, is then tested using a Student's <em>t<\/em>-test for a single population mean with <em>n<\/em> \u2013 1 degrees of freedom, where <em>n<\/em> is the number of differences.\r\n\r\nThe test statistic (<em>t<\/em>-score) is:\r\n\r\n[latex]\\displaystyle{t}=\\dfrac{{\\overline{{x}}_{{d}}-{\\mu}_{{d}}}}{{{(\\dfrac{{s}_{{d}}}{\\sqrt{{n}}})}}}[\/latex]\r\n<div class=\"textbox examples\">\r\n<h3>Recall: ORDER OF OPERATIONS<\/h3>\r\n<div align=\"left\">\r\n<table style=\"border-collapse: collapse; width: 100%; height: 36px;\" border=\"1\">\r\n<tbody>\r\n<tr style=\"height: 12px;\">\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Please<\/strong><\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Excuse<\/strong><\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>My<\/strong><\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Dear<\/strong><\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Aunt<\/strong><\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Sally<\/strong><\/td>\r\n<\/tr>\r\n<tr style=\"height: 12px;\">\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">parentheses<\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">exponents<\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">multiplication<\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">division<\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">addition<\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">subtraction<\/td>\r\n<\/tr>\r\n<tr style=\"height: 12px;\">\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">[latex]( \\ )[\/latex]<\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">[latex]x^2[\/latex]<\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\" colspan=\"2\">[latex]\\times \\ \\mathrm{or} \\ \\div[\/latex]<\/td>\r\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\" colspan=\"2\">[latex]+ \\ \\mathrm{or} \\ -[\/latex]<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<h2><strong>To calculate the test statistic (<em>t<\/em>-score) follow these steps:<\/strong><\/h2>\r\n<strong>First, find the numerator. Calculate the difference between the matched or paired sample mean and the population mean for the differences, [latex](\\overline{x} _d - \\mu _d)[\/latex].<\/strong>\r\n\r\n<strong>Second, find the denominator.<\/strong>\r\n\r\nStep 1: Find the square root of the sample size (number of differences), [latex]\\sqrt{n}[\/latex].\r\n\r\nStep 2: Take the population standard deviation for the differences and divide by the value you found in Step 1.\r\n\r\n<strong>Third, take the numerator and divide by the denominator.<\/strong>\r\n\r\n<\/div>\r\n<\/div>\r\nhttps:\/\/www.youtube.com\/embed\/5ABpqVSx33I\r\n<div class=\"textbox exercises\">\r\n<h3>Example 1<\/h3>\r\nA study was conducted to investigate the effectiveness of hypnotism in reducing pain. Results for randomly selected subjects are shown in the table below. A lower score indicates less pain. The \"before\" value is matched to an \"after\" value and the differences are calculated. The differences have a normal distribution. Are the sensory measurements, on average, lower after hypnotism? Test at a 5% significance level.\r\n<table>\r\n<thead>\r\n<tr>\r\n<th>Subject:<\/th>\r\n<th>A<\/th>\r\n<th>B<\/th>\r\n<th>C<\/th>\r\n<th>D<\/th>\r\n<th>E<\/th>\r\n<th>F<\/th>\r\n<th>G<\/th>\r\n<th>H<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td>Before<\/td>\r\n<td>6.6<\/td>\r\n<td>6.5<\/td>\r\n<td>9.0<\/td>\r\n<td>10.3<\/td>\r\n<td>11.3<\/td>\r\n<td>8.1<\/td>\r\n<td>6.3<\/td>\r\n<td>11.6<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>After<\/td>\r\n<td>6.8<\/td>\r\n<td>2.4<\/td>\r\n<td>7.4<\/td>\r\n<td>8.5<\/td>\r\n<td>8.1<\/td>\r\n<td>6.1<\/td>\r\n<td>3.4<\/td>\r\n<td>2.0<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n[reveal-answer q=\"651770\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"651770\"]\r\n\r\nCorresponding \"before\" and \"after\" values form matched pairs. (Calculate \"after\" \u2013 \"before.\")\r\n<table>\r\n<thead>\r\n<tr>\r\n<th>After Data<\/th>\r\n<th>Before Data<\/th>\r\n<th>Difference<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td>6.8<\/td>\r\n<td>6.6<\/td>\r\n<td>0.2<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>2.4<\/td>\r\n<td>6.5<\/td>\r\n<td>-4.1<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>7.4<\/td>\r\n<td>9<\/td>\r\n<td>-1.6<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>8.5<\/td>\r\n<td>10.3<\/td>\r\n<td>-1.8<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>8.1<\/td>\r\n<td>11.3<\/td>\r\n<td>-3.2<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>6.1<\/td>\r\n<td>8.1<\/td>\r\n<td>-2<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>3.4<\/td>\r\n<td>6.3<\/td>\r\n<td>-2.9<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>2<\/td>\r\n<td>11.6<\/td>\r\n<td>-9.6<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nThe data <strong>for the test<\/strong> are the differences: {0.2, \u20134.1, \u20131.6, \u20131.8, \u20133.2, \u20132, \u20132.9, \u20139.6}\r\n\r\nThe sample mean and sample standard deviation of the differences are: [latex]\\displaystyle\\overline{{x}}_{{d}}=-{3.13}{\\quad\\text{and}\\quad}{s}_{{d}}={2.91}[\/latex]. Verify these values.\r\n\r\nLet [latex]{\\mu}_{d}[\/latex] be the population mean for the differences. We use the subscript to denote \"differences.\"\r\n\r\n<strong>Random variable:<\/strong> [latex]\\displaystyle\\overline{{X}}_{{d}}[\/latex] = the mean difference of the sensory measurements\r\n\r\n<em>H<sub data-redactor-tag=\"sub\">0<\/sub><\/em>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> \u2265 0\r\n\r\nThe null hypothesis is zero or positive, meaning that there is the same or more pain felt after hypnotism. That means the subject shows no improvement. <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> is the population mean of the differences.)\r\n\r\n<em>H<sub data-redactor-tag=\"sub\">a<\/sub><\/em>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> &lt; 0\r\n\r\nThe alternative hypothesis is negative, meaning there is less pain felt after hypnotism. That means the subject shows improvement. The score should be lower after hypnotism, so the difference ought to be negative to indicate improvement.\r\n\r\n<strong>Distribution for the test: <\/strong>The distribution is a Student's <em>t<\/em> with <em>df<\/em> = <em>n <\/em>\u2013 1 = 8 \u2013 1 = 7. Use <em>t<\/em><sub>7<\/sub>. <strong>(Notice that the test is for a single population mean.)<\/strong>\r\n\r\n<strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value using the Student's <em>t<\/em>-distribution: <\/strong><em>p<\/em>-value = 0.0095\r\n\r\n<strong>Graph:<\/strong>\r\n\r\n<img class=\"aligncenter wp-image-2133 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/5668\/2021\/07\/01181949\/ac7f0524a462317da0579623917f65415c4b6938.jpeg\" alt=\"Normal distribution curve of the average difference of sensory measurements with values of -3.13 and 0. A vertical upward line extends from -3.13 to the curve, and the p-value is indicated in the area to the left of this value.\" width=\"487\" height=\"208\" \/>\r\n\r\n[latex]\\displaystyle\\overline{{X}}_{{d}}[\/latex] is the random variable for the differences.\r\n\r\nThe sample mean and sample standard deviation of the differences are:\r\n\r\n[latex]\\displaystyle\\overline{{x}}_{{d}}=-{3.13}[\/latex]\r\n\r\n[latex]\\displaystyle{s}_{{d}}={2.91}[\/latex]\r\n\r\n<strong>Compare <em data-redactor-tag=\"em\">\u03b1<\/em> and the <em>p<\/em>-value:<\/strong> <em>\u03b1<\/em> = 0.05 and <em>p<\/em>-value = 0.0095. <em>\u03b1<\/em> &gt; <em>p<\/em>-value.\r\n\r\n<strong>Make a decision:<\/strong>\u00a0since <em>\u03b1<\/em> &gt; <em>p<\/em>-value, reject <em>H<sub data-redactor-tag=\"sub\">0<\/sub><\/em>. This means that <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> &lt; 0 and there is improvement.\r\n\r\n<strong>Conclusion:<\/strong>\u00a0at a 5% level of significance, from the sample data, there is sufficient evidence to conclude that the sensory measurements, on average, are lower after hypnotism. Hypnotism appears to be effective in reducing pain.\r\n\r\n[\/hidden-answer]\r\n<h4>Note<\/h4>\r\nFor the TI-83+ and TI-84 calculators, you can either calculate the differences ahead of time (after \u2013 before) and put the differences into a list or you can put the after data into a first list and the before data into a second list. Then, go to a third list and arrow up to the name. Enter 1st list name \u2013 2nd list name. The calculator will do the subtraction, and you will have the differences in the third list.\r\n\r\n<header>\r\n<h4 class=\"os-title\" data-type=\"title\"><span class=\"os-title-label\">USING THE TI-83, 83+, 84, 84+ CALCULATOR<\/span><\/h4>\r\n<\/header><section>\r\n<div class=\"os-note-body\"><\/div>\r\n<\/section>\r\n<ul>\r\n \t<li>Use your list of differences as the data.<\/li>\r\n \t<li>Press\u00a0<code style=\"line-height: 1.6em;\">STAT<\/code> and arrow over to <code style=\"line-height: 1.6em;\">TESTS<\/code>.<\/li>\r\n \t<li>Press <code style=\"line-height: 1.6em;\">2:T-Test<\/code>.<\/li>\r\n \t<li>Arrow over to <code style=\"line-height: 1.6em;\">Data<\/code> and press <code style=\"line-height: 1.6em;\">ENTER<\/code>.<\/li>\r\n \t<li>Arrow down and enter <code style=\"line-height: 1.6em;\">0<\/code> for the name of the list where you put the data, and <code style=\"line-height: 1.6em;\">1<\/code> for Freq:.<\/li>\r\n \t<li>Arrow down to <code style=\"line-height: 1.6em;\">\u03bc<\/code>: and arrow over to <code style=\"line-height: 1.6em;\">&lt;<\/code>.<\/li>\r\n \t<li>Press <code style=\"line-height: 1.6em;\">ENTER<\/code>.<\/li>\r\n \t<li>Arrow down to <code style=\"line-height: 1.6em;\">Calculate<\/code> and press <code style=\"line-height: 1.6em;\">ENTER<\/code>.<\/li>\r\n \t<li>The <em>p<\/em>-value is 0.0094, and the test statistic is \u20133.04.<\/li>\r\n \t<li>Do these instructions again except, arrow to <code style=\"line-height: 1.6em;\">Draw<\/code> (instead of <code style=\"line-height: 1.6em;\">Calculate<\/code>). Press <code style=\"line-height: 1.6em;\">ENTER<\/code>.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>try it 1<\/h3>\r\nA study was conducted to investigate how effective a new diet was in lowering cholesterol. Results for the randomly selected subjects are shown in the table. The differences have a normal distribution. Are the subjects' cholesterol levels lower on average after the diet? Test at the 5% level.\r\n<table>\r\n<tbody>\r\n<tr>\r\n<td>Subject<\/td>\r\n<td>A<\/td>\r\n<td>B<\/td>\r\n<td>C<\/td>\r\n<td>D<\/td>\r\n<td>E<\/td>\r\n<td>F<\/td>\r\n<td>G<\/td>\r\n<td>H<\/td>\r\n<td>I<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>Before<\/td>\r\n<td>209<\/td>\r\n<td>210<\/td>\r\n<td>205<\/td>\r\n<td>198<\/td>\r\n<td>216<\/td>\r\n<td>217<\/td>\r\n<td>238<\/td>\r\n<td>240<\/td>\r\n<td>222<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>After<\/td>\r\n<td>199<\/td>\r\n<td>207<\/td>\r\n<td>189<\/td>\r\n<td>209<\/td>\r\n<td>217<\/td>\r\n<td>202<\/td>\r\n<td>211<\/td>\r\n<td>223<\/td>\r\n<td>201<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n[reveal-answer q=\"391953\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"391953\"]\r\n\r\nThe <em>p<\/em>-value is 0.0130, so we can reject the null hypothesis. There is enough evidence to suggest that the diet lowers cholesterol.\r\n\r\n[\/hidden-answer]\r\n\r\n<\/div>\r\n<h3><\/h3>\r\n<div class=\"textbox exercises\">\r\n<h3>Example 2<\/h3>\r\nA college football coach was interested in whether the college's strength development class increased his players' maximum lift (in pounds) on the bench press exercise. He asked four of his players to participate in a study. The amount of weight they could each lift was recorded before they took the strength development class. After completing the class, the amount of weight they could each lift was again measured. The data are as follows:\r\n<table>\r\n<thead>\r\n<tr>\r\n<th>Weight (in pounds)<\/th>\r\n<th>Player 1<\/th>\r\n<th>Player 2<\/th>\r\n<th>Player 3<\/th>\r\n<th>Player 4<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td>Amount of weight lifted prior to the class<\/td>\r\n<td>205<\/td>\r\n<td>241<\/td>\r\n<td>338<\/td>\r\n<td>368<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>Amount of weight lifted after the class<\/td>\r\n<td>295<\/td>\r\n<td>252<\/td>\r\n<td>330<\/td>\r\n<td>360<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nThe coach wants to know if the strength development class makes his players stronger, on average.\r\n[reveal-answer q=\"741609\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"741609\"]\r\n\r\nRecord the <strong>differences<\/strong> data. Calculate the differences by subtracting the amount of weight lifted prior to the class from the weight lifted after completing the class. The data for the differences are: {90, 11, -8, -8}. Assume the differences have a normal distribution.\r\n\r\nUsing the differences data, calculate the sample mean and the sample standard deviation.\r\n\r\n[latex]\\displaystyle\\overline{{x}}_{{d}}={21.3},{s}_{{d}}={46.7}[\/latex]\r\n<h4>Note<\/h4>\r\nThe data given here would indicate that the distribution is actually right-skewed. The difference 90 may be an extreme outlier? It is pulling the sample mean to be 21.3 (positive). The means of the other three data values are actually negative.\r\n\r\nUsing the difference data, this becomes a test of a single __________ (fill in the blank).\r\n\r\n<strong>Define the random variable:<\/strong> [latex]\\displaystyle\\overline{{X}}_{{d}}[\/latex] mean difference in the maximum lift per player.\r\n\r\nThe distribution for the hypothesis test is <em>t<sub data-redactor-tag=\"sub\">3<\/sub><\/em>.\r\n\r\n<em>H<sub data-redactor-tag=\"sub\">0<\/sub><\/em>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> \u2264 0, <em>H<sub data-redactor-tag=\"sub\">a<\/sub><\/em>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> &gt; 0\r\n\r\n<strong>Graph:<\/strong>\r\n\r\n<img class=\"aligncenter wp-image-2134 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/5668\/2021\/07\/01182055\/82c5395d278b781e824eee8f49dda35b5f60bf73.jpeg\" alt=\"Normal distribution curve with values of 0 and 21.3. A vertical upward line extends from 21.3 to the curve and the p-value is indicated in the area to the right of this value.\" width=\"487\" height=\"182\" \/>\r\n\r\n<strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value:<\/strong>\u00a0the <em>p<\/em>-value is 0.2150\r\n\r\n<strong>Decision:<\/strong>\u00a0if the level of significance is 5%, the decision is not to reject the null hypothesis, because \u03b1 &lt; <em>p<\/em>-value.\r\n\r\n<strong>Conclusion: a<\/strong>t a 5% level of significance, from the sample data, there is not sufficient evidence to conclude that the strength development class helped to make the players stronger, on average.\r\n\r\n[\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>try it 2<\/h3>\r\nA new prep class was designed to improve SAT test scores. Five students were selected at random. Their scores on two practice exams were recorded, one before the class and one after. The data recorded in this table. Are the scores, on average, higher after the class? Test at a 5% level.\r\n<table>\r\n<thead>\r\n<tr>\r\n<th>SAT Scores<\/th>\r\n<th>Student 1<\/th>\r\n<th>Student 2<\/th>\r\n<th>Student 3<\/th>\r\n<th>Student 4<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td>Score before class<\/td>\r\n<td>1840<\/td>\r\n<td>1960<\/td>\r\n<td>1920<\/td>\r\n<td>2150<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>Score after class<\/td>\r\n<td>1920<\/td>\r\n<td>2160<\/td>\r\n<td>2200<\/td>\r\n<td>2100<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n[reveal-answer q=\"380723\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"380723\"]\r\n\r\nThe <em>p<\/em>-value is 0.0874, so we decline to reject the null hypothesis. The data do not support that the class improves SAT scores significantly.\r\n\r\n[\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Example 3<\/h3>\r\nSeven eighth-graders at Kennedy Middle School measured how far they could push the shot-put with their dominant (writing) hand and their weaker (non-writing) hand. They thought that they could push equal distances with either hand. The data were collected and recorded in this table.\r\n<table>\r\n<thead>\r\n<tr>\r\n<th>Distance (in feet) using<\/th>\r\n<th>Student 1<\/th>\r\n<th>Student 2<\/th>\r\n<th>Student 3<\/th>\r\n<th>Student 4<\/th>\r\n<th>Student 5<\/th>\r\n<th>Student 6<\/th>\r\n<th>Student 7<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td>Dominant Hand<\/td>\r\n<td>30<\/td>\r\n<td>26<\/td>\r\n<td>34<\/td>\r\n<td>17<\/td>\r\n<td>19<\/td>\r\n<td>26<\/td>\r\n<td>20<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>Weaker Hand<\/td>\r\n<td>28<\/td>\r\n<td>14<\/td>\r\n<td>27<\/td>\r\n<td>18<\/td>\r\n<td>17<\/td>\r\n<td>26<\/td>\r\n<td>16<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nConduct a hypothesis test to determine whether the mean difference in distances between the children's dominant versus weaker hands is significant.\r\n\r\n[reveal-answer q=\"58390\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"58390\"]\r\n\r\nRecord the <strong>differences<\/strong> data. Calculate the differences by subtracting the distances with the weaker hand from the distances with the dominant hand. The data for the differences are: {2, 12, 7, \u20131, 2, 0, 4}. The differences have a normal distribution.\r\n\r\nUsing the differences data, calculate the sample mean and the sample standard deviation. [latex]\\displaystyle\\overline{{x}}_{{d}}={3.71},{s}_{{d}}={4.5}[\/latex].\r\n\r\n<strong>Random variable:<\/strong> [latex]\\displaystyle\\overline{{X}}_{{d}}[\/latex] = mean difference in the distances between the hands.\r\n\r\n<strong>Distribution for the hypothesis test:\u00a0<\/strong><em>t<sub data-redactor-tag=\"sub\">6<\/sub><\/em>\r\n\r\n<em>H<\/em><sub>0<\/sub>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> = 0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0<em>H<\/em><em><sub data-redactor-tag=\"sub\">a<\/sub><\/em>: <em>\u03bc<\/em><em><sub data-redactor-tag=\"sub\">d<\/sub><\/em> \u2260 0\r\n\r\n<strong>Graph:<\/strong>\r\n\r\n<img class=\"aligncenter wp-image-2135 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/5668\/2021\/07\/01182302\/241d9297afa0ff25a21010d7cb0b1fc9847d0f4b.jpeg\" alt=\"This is a normal distribution curve with mean equal to zero. Both the right and left tails of the curve are shaded. Each tail represents 1\/2(p-value) = 0.0358.\" width=\"487\" height=\"177\" \/>\r\n\r\n<strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value:<\/strong>\u00a0the <em>p<\/em>-value is 0.0716 (using the data directly).\r\n\r\n(test statistic = 2.18. <em>p<\/em>-value = 0.0719 using ([latex]{\\overline x} = 3.71, {s_d} = 4.5[\/latex].)\r\n\r\n<strong>Decision:<\/strong>\u00a0assume <em>\u03b1<\/em> = 0.05. Since <em>\u03b1<\/em> &lt; <em>p<\/em>-value, Do not reject <em>H<sub data-redactor-tag=\"sub\">0<\/sub><\/em>.\r\n\r\n<strong>Conclusion:<\/strong>\u00a0at the 5% level of significance, from the sample data, there is not sufficient evidence to conclude that there is a difference in the children's weaker and dominant hands to push the shot-put.\r\n\r\n[\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>try it 3<\/h3>\r\nFive ball players think they can throw the same distance with their dominant hand (throwing) and off-hand (catching hand). The data were collected and recorded in the table below. Conduct a hypothesis test to determine whether the mean difference in distances between the dominant and off-hand is significant. Test at the 5% level.\r\n<table style=\"border-collapse: collapse; width: 100%; height: 36px;\" border=\"0\">\r\n<thead>\r\n<tr style=\"height: 12px;\">\r\n<td class=\"shaded\" style=\"width: 16.6667%; height: 12px;\"><\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Player 1<\/strong><\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Player 2<\/strong><\/td>\r\n<th style=\"width: 16.6667%; height: 12px;\"><strong>Player 3<\/strong><\/th>\r\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Player 4<\/strong><\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Player 5<\/strong><\/td>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr style=\"height: 12px;\">\r\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Dominant Hand<\/strong><\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">120<\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">111<\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">135<\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">140<\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">125<\/td>\r\n<\/tr>\r\n<tr style=\"height: 12px;\">\r\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Off-hand<\/strong><\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">105<\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">109<\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">98<\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">111<\/td>\r\n<td style=\"width: 16.6667%; height: 12px;\">99<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n[reveal-answer q=\"578994\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"578994\"]\r\n\r\nThe <em>p<\/em>-level is 0.0230, so we can reject the null hypothesis. The data show that the players do not throw the same distance with their off-hands as they do with their dominant hands.\r\n\r\n[\/hidden-answer]\r\n\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<section>\n<ul>\n<li>Conduct a hypothesis test for matched or paired data and interpret the conclusion in context<\/li>\n<\/ul>\n<\/section>\n<\/div>\n<p>When using a hypothesis test for matched or paired samples, the following characteristics should be present:<\/p>\n<ol>\n<li>Simple random sampling is used.<\/li>\n<li>Sample sizes are often small.<\/li>\n<li>Two measurements (samples) are drawn from the same pair of individuals or objects.<\/li>\n<li>Differences are calculated from the matched or paired samples.<\/li>\n<li>The differences form the sample that is used for the hypothesis test.<\/li>\n<li>Either the matched pairs have differences that come from a population that is normal or the number of differences is sufficiently large so that distribution of the sample mean of differences is approximately normal.<\/li>\n<\/ol>\n<p>In a hypothesis test for matched or paired samples, subjects are matched in pairs, and differences are calculated. The differences are the data. The population mean for the differences, <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em>, is then tested using a Student&#8217;s <em>t<\/em>-test for a single population mean with <em>n<\/em> \u2013 1 degrees of freedom, where <em>n<\/em> is the number of differences.<\/p>\n<p>The test statistic (<em>t<\/em>-score) is:<\/p>\n<p>[latex]\\displaystyle{t}=\\dfrac{{\\overline{{x}}_{{d}}-{\\mu}_{{d}}}}{{{(\\dfrac{{s}_{{d}}}{\\sqrt{{n}}})}}}[\/latex]<\/p>\n<div class=\"textbox examples\">\n<h3>Recall: ORDER OF OPERATIONS<\/h3>\n<div style=\"text-align: left;\">\n<table style=\"border-collapse: collapse; width: 100%; height: 36px;\">\n<tbody>\n<tr style=\"height: 12px;\">\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Please<\/strong><\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Excuse<\/strong><\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>My<\/strong><\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Dear<\/strong><\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Aunt<\/strong><\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\"><strong>Sally<\/strong><\/td>\n<\/tr>\n<tr style=\"height: 12px;\">\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">parentheses<\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">exponents<\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">multiplication<\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">division<\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">addition<\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">subtraction<\/td>\n<\/tr>\n<tr style=\"height: 12px;\">\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">[latex]( \\ )[\/latex]<\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\">[latex]x^2[\/latex]<\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\" colspan=\"2\">[latex]\\times \\ \\mathrm{or} \\ \\div[\/latex]<\/td>\n<td style=\"width: 16.6667%; height: 12px; text-align: center;\" colspan=\"2\">[latex]+ \\ \\mathrm{or} \\ -[\/latex]<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2><strong>To calculate the test statistic (<em>t<\/em>-score) follow these steps:<\/strong><\/h2>\n<p><strong>First, find the numerator. Calculate the difference between the matched or paired sample mean and the population mean for the differences, [latex](\\overline{x} _d - \\mu _d)[\/latex].<\/strong><\/p>\n<p><strong>Second, find the denominator.<\/strong><\/p>\n<p>Step 1: Find the square root of the sample size (number of differences), [latex]\\sqrt{n}[\/latex].<\/p>\n<p>Step 2: Take the population standard deviation for the differences and divide by the value you found in Step 1.<\/p>\n<p><strong>Third, take the numerator and divide by the denominator.<\/strong><\/p>\n<\/div>\n<\/div>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Z-statistics vs. T-statistics | Inferential statistics | Probability and Statistics | Khan Academy\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/5ABpqVSx33I?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<div class=\"textbox exercises\">\n<h3>Example 1<\/h3>\n<p>A study was conducted to investigate the effectiveness of hypnotism in reducing pain. Results for randomly selected subjects are shown in the table below. A lower score indicates less pain. The &#8220;before&#8221; value is matched to an &#8220;after&#8221; value and the differences are calculated. The differences have a normal distribution. Are the sensory measurements, on average, lower after hypnotism? Test at a 5% significance level.<\/p>\n<table>\n<thead>\n<tr>\n<th>Subject:<\/th>\n<th>A<\/th>\n<th>B<\/th>\n<th>C<\/th>\n<th>D<\/th>\n<th>E<\/th>\n<th>F<\/th>\n<th>G<\/th>\n<th>H<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Before<\/td>\n<td>6.6<\/td>\n<td>6.5<\/td>\n<td>9.0<\/td>\n<td>10.3<\/td>\n<td>11.3<\/td>\n<td>8.1<\/td>\n<td>6.3<\/td>\n<td>11.6<\/td>\n<\/tr>\n<tr>\n<td>After<\/td>\n<td>6.8<\/td>\n<td>2.4<\/td>\n<td>7.4<\/td>\n<td>8.5<\/td>\n<td>8.1<\/td>\n<td>6.1<\/td>\n<td>3.4<\/td>\n<td>2.0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q651770\">Show Answer<\/span><\/p>\n<div id=\"q651770\" class=\"hidden-answer\" style=\"display: none\">\n<p>Corresponding &#8220;before&#8221; and &#8220;after&#8221; values form matched pairs. (Calculate &#8220;after&#8221; \u2013 &#8220;before.&#8221;)<\/p>\n<table>\n<thead>\n<tr>\n<th>After Data<\/th>\n<th>Before Data<\/th>\n<th>Difference<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>6.8<\/td>\n<td>6.6<\/td>\n<td>0.2<\/td>\n<\/tr>\n<tr>\n<td>2.4<\/td>\n<td>6.5<\/td>\n<td>-4.1<\/td>\n<\/tr>\n<tr>\n<td>7.4<\/td>\n<td>9<\/td>\n<td>-1.6<\/td>\n<\/tr>\n<tr>\n<td>8.5<\/td>\n<td>10.3<\/td>\n<td>-1.8<\/td>\n<\/tr>\n<tr>\n<td>8.1<\/td>\n<td>11.3<\/td>\n<td>-3.2<\/td>\n<\/tr>\n<tr>\n<td>6.1<\/td>\n<td>8.1<\/td>\n<td>-2<\/td>\n<\/tr>\n<tr>\n<td>3.4<\/td>\n<td>6.3<\/td>\n<td>-2.9<\/td>\n<\/tr>\n<tr>\n<td>2<\/td>\n<td>11.6<\/td>\n<td>-9.6<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The data <strong>for the test<\/strong> are the differences: {0.2, \u20134.1, \u20131.6, \u20131.8, \u20133.2, \u20132, \u20132.9, \u20139.6}<\/p>\n<p>The sample mean and sample standard deviation of the differences are: [latex]\\displaystyle\\overline{{x}}_{{d}}=-{3.13}{\\quad\\text{and}\\quad}{s}_{{d}}={2.91}[\/latex]. Verify these values.<\/p>\n<p>Let [latex]{\\mu}_{d}[\/latex] be the population mean for the differences. We use the subscript to denote &#8220;differences.&#8221;<\/p>\n<p><strong>Random variable:<\/strong> [latex]\\displaystyle\\overline{{X}}_{{d}}[\/latex] = the mean difference of the sensory measurements<\/p>\n<p><em>H<sub data-redactor-tag=\"sub\">0<\/sub><\/em>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> \u2265 0<\/p>\n<p>The null hypothesis is zero or positive, meaning that there is the same or more pain felt after hypnotism. That means the subject shows no improvement. <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> is the population mean of the differences.)<\/p>\n<p><em>H<sub data-redactor-tag=\"sub\">a<\/sub><\/em>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> &lt; 0<\/p>\n<p>The alternative hypothesis is negative, meaning there is less pain felt after hypnotism. That means the subject shows improvement. The score should be lower after hypnotism, so the difference ought to be negative to indicate improvement.<\/p>\n<p><strong>Distribution for the test: <\/strong>The distribution is a Student&#8217;s <em>t<\/em> with <em>df<\/em> = <em>n <\/em>\u2013 1 = 8 \u2013 1 = 7. Use <em>t<\/em><sub>7<\/sub>. <strong>(Notice that the test is for a single population mean.)<\/strong><\/p>\n<p><strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value using the Student&#8217;s <em>t<\/em>-distribution: <\/strong><em>p<\/em>-value = 0.0095<\/p>\n<p><strong>Graph:<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-2133 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/5668\/2021\/07\/01181949\/ac7f0524a462317da0579623917f65415c4b6938.jpeg\" alt=\"Normal distribution curve of the average difference of sensory measurements with values of -3.13 and 0. A vertical upward line extends from -3.13 to the curve, and the p-value is indicated in the area to the left of this value.\" width=\"487\" height=\"208\" \/><\/p>\n<p>[latex]\\displaystyle\\overline{{X}}_{{d}}[\/latex] is the random variable for the differences.<\/p>\n<p>The sample mean and sample standard deviation of the differences are:<\/p>\n<p>[latex]\\displaystyle\\overline{{x}}_{{d}}=-{3.13}[\/latex]<\/p>\n<p>[latex]\\displaystyle{s}_{{d}}={2.91}[\/latex]<\/p>\n<p><strong>Compare <em data-redactor-tag=\"em\">\u03b1<\/em> and the <em>p<\/em>-value:<\/strong> <em>\u03b1<\/em> = 0.05 and <em>p<\/em>-value = 0.0095. <em>\u03b1<\/em> &gt; <em>p<\/em>-value.<\/p>\n<p><strong>Make a decision:<\/strong>\u00a0since <em>\u03b1<\/em> &gt; <em>p<\/em>-value, reject <em>H<sub data-redactor-tag=\"sub\">0<\/sub><\/em>. This means that <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> &lt; 0 and there is improvement.<\/p>\n<p><strong>Conclusion:<\/strong>\u00a0at a 5% level of significance, from the sample data, there is sufficient evidence to conclude that the sensory measurements, on average, are lower after hypnotism. Hypnotism appears to be effective in reducing pain.<\/p>\n<\/div>\n<\/div>\n<h4>Note<\/h4>\n<p>For the TI-83+ and TI-84 calculators, you can either calculate the differences ahead of time (after \u2013 before) and put the differences into a list or you can put the after data into a first list and the before data into a second list. Then, go to a third list and arrow up to the name. Enter 1st list name \u2013 2nd list name. The calculator will do the subtraction, and you will have the differences in the third list.<\/p>\n<header>\n<h4 class=\"os-title\" data-type=\"title\"><span class=\"os-title-label\">USING THE TI-83, 83+, 84, 84+ CALCULATOR<\/span><\/h4>\n<\/header>\n<section>\n<div class=\"os-note-body\"><\/div>\n<\/section>\n<ul>\n<li>Use your list of differences as the data.<\/li>\n<li>Press\u00a0<code style=\"line-height: 1.6em;\">STAT<\/code> and arrow over to <code style=\"line-height: 1.6em;\">TESTS<\/code>.<\/li>\n<li>Press <code style=\"line-height: 1.6em;\">2:T-Test<\/code>.<\/li>\n<li>Arrow over to <code style=\"line-height: 1.6em;\">Data<\/code> and press <code style=\"line-height: 1.6em;\">ENTER<\/code>.<\/li>\n<li>Arrow down and enter <code style=\"line-height: 1.6em;\">0<\/code> for the name of the list where you put the data, and <code style=\"line-height: 1.6em;\">1<\/code> for Freq:.<\/li>\n<li>Arrow down to <code style=\"line-height: 1.6em;\">\u03bc<\/code>: and arrow over to <code style=\"line-height: 1.6em;\">&lt;<\/code>.<\/li>\n<li>Press <code style=\"line-height: 1.6em;\">ENTER<\/code>.<\/li>\n<li>Arrow down to <code style=\"line-height: 1.6em;\">Calculate<\/code> and press <code style=\"line-height: 1.6em;\">ENTER<\/code>.<\/li>\n<li>The <em>p<\/em>-value is 0.0094, and the test statistic is \u20133.04.<\/li>\n<li>Do these instructions again except, arrow to <code style=\"line-height: 1.6em;\">Draw<\/code> (instead of <code style=\"line-height: 1.6em;\">Calculate<\/code>). Press <code style=\"line-height: 1.6em;\">ENTER<\/code>.<\/li>\n<\/ul>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>try it 1<\/h3>\n<p>A study was conducted to investigate how effective a new diet was in lowering cholesterol. Results for the randomly selected subjects are shown in the table. The differences have a normal distribution. Are the subjects&#8217; cholesterol levels lower on average after the diet? Test at the 5% level.<\/p>\n<table>\n<tbody>\n<tr>\n<td>Subject<\/td>\n<td>A<\/td>\n<td>B<\/td>\n<td>C<\/td>\n<td>D<\/td>\n<td>E<\/td>\n<td>F<\/td>\n<td>G<\/td>\n<td>H<\/td>\n<td>I<\/td>\n<\/tr>\n<tr>\n<td>Before<\/td>\n<td>209<\/td>\n<td>210<\/td>\n<td>205<\/td>\n<td>198<\/td>\n<td>216<\/td>\n<td>217<\/td>\n<td>238<\/td>\n<td>240<\/td>\n<td>222<\/td>\n<\/tr>\n<tr>\n<td>After<\/td>\n<td>199<\/td>\n<td>207<\/td>\n<td>189<\/td>\n<td>209<\/td>\n<td>217<\/td>\n<td>202<\/td>\n<td>211<\/td>\n<td>223<\/td>\n<td>201<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q391953\">Show Answer<\/span><\/p>\n<div id=\"q391953\" class=\"hidden-answer\" style=\"display: none\">\n<p>The <em>p<\/em>-value is 0.0130, so we can reject the null hypothesis. There is enough evidence to suggest that the diet lowers cholesterol.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<h3><\/h3>\n<div class=\"textbox exercises\">\n<h3>Example 2<\/h3>\n<p>A college football coach was interested in whether the college&#8217;s strength development class increased his players&#8217; maximum lift (in pounds) on the bench press exercise. He asked four of his players to participate in a study. The amount of weight they could each lift was recorded before they took the strength development class. After completing the class, the amount of weight they could each lift was again measured. The data are as follows:<\/p>\n<table>\n<thead>\n<tr>\n<th>Weight (in pounds)<\/th>\n<th>Player 1<\/th>\n<th>Player 2<\/th>\n<th>Player 3<\/th>\n<th>Player 4<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Amount of weight lifted prior to the class<\/td>\n<td>205<\/td>\n<td>241<\/td>\n<td>338<\/td>\n<td>368<\/td>\n<\/tr>\n<tr>\n<td>Amount of weight lifted after the class<\/td>\n<td>295<\/td>\n<td>252<\/td>\n<td>330<\/td>\n<td>360<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The coach wants to know if the strength development class makes his players stronger, on average.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q741609\">Show Answer<\/span><\/p>\n<div id=\"q741609\" class=\"hidden-answer\" style=\"display: none\">\n<p>Record the <strong>differences<\/strong> data. Calculate the differences by subtracting the amount of weight lifted prior to the class from the weight lifted after completing the class. The data for the differences are: {90, 11, -8, -8}. Assume the differences have a normal distribution.<\/p>\n<p>Using the differences data, calculate the sample mean and the sample standard deviation.<\/p>\n<p>[latex]\\displaystyle\\overline{{x}}_{{d}}={21.3},{s}_{{d}}={46.7}[\/latex]<\/p>\n<h4>Note<\/h4>\n<p>The data given here would indicate that the distribution is actually right-skewed. The difference 90 may be an extreme outlier? It is pulling the sample mean to be 21.3 (positive). The means of the other three data values are actually negative.<\/p>\n<p>Using the difference data, this becomes a test of a single __________ (fill in the blank).<\/p>\n<p><strong>Define the random variable:<\/strong> [latex]\\displaystyle\\overline{{X}}_{{d}}[\/latex] mean difference in the maximum lift per player.<\/p>\n<p>The distribution for the hypothesis test is <em>t<sub data-redactor-tag=\"sub\">3<\/sub><\/em>.<\/p>\n<p><em>H<sub data-redactor-tag=\"sub\">0<\/sub><\/em>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> \u2264 0, <em>H<sub data-redactor-tag=\"sub\">a<\/sub><\/em>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> &gt; 0<\/p>\n<p><strong>Graph:<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-2134 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/5668\/2021\/07\/01182055\/82c5395d278b781e824eee8f49dda35b5f60bf73.jpeg\" alt=\"Normal distribution curve with values of 0 and 21.3. A vertical upward line extends from 21.3 to the curve and the p-value is indicated in the area to the right of this value.\" width=\"487\" height=\"182\" \/><\/p>\n<p><strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value:<\/strong>\u00a0the <em>p<\/em>-value is 0.2150<\/p>\n<p><strong>Decision:<\/strong>\u00a0if the level of significance is 5%, the decision is not to reject the null hypothesis, because \u03b1 &lt; <em>p<\/em>-value.<\/p>\n<p><strong>Conclusion: a<\/strong>t a 5% level of significance, from the sample data, there is not sufficient evidence to conclude that the strength development class helped to make the players stronger, on average.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>try it 2<\/h3>\n<p>A new prep class was designed to improve SAT test scores. Five students were selected at random. Their scores on two practice exams were recorded, one before the class and one after. The data recorded in this table. Are the scores, on average, higher after the class? Test at a 5% level.<\/p>\n<table>\n<thead>\n<tr>\n<th>SAT Scores<\/th>\n<th>Student 1<\/th>\n<th>Student 2<\/th>\n<th>Student 3<\/th>\n<th>Student 4<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Score before class<\/td>\n<td>1840<\/td>\n<td>1960<\/td>\n<td>1920<\/td>\n<td>2150<\/td>\n<\/tr>\n<tr>\n<td>Score after class<\/td>\n<td>1920<\/td>\n<td>2160<\/td>\n<td>2200<\/td>\n<td>2100<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q380723\">Show Answer<\/span><\/p>\n<div id=\"q380723\" class=\"hidden-answer\" style=\"display: none\">\n<p>The <em>p<\/em>-value is 0.0874, so we decline to reject the null hypothesis. The data do not support that the class improves SAT scores significantly.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Example 3<\/h3>\n<p>Seven eighth-graders at Kennedy Middle School measured how far they could push the shot-put with their dominant (writing) hand and their weaker (non-writing) hand. They thought that they could push equal distances with either hand. The data were collected and recorded in this table.<\/p>\n<table>\n<thead>\n<tr>\n<th>Distance (in feet) using<\/th>\n<th>Student 1<\/th>\n<th>Student 2<\/th>\n<th>Student 3<\/th>\n<th>Student 4<\/th>\n<th>Student 5<\/th>\n<th>Student 6<\/th>\n<th>Student 7<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Dominant Hand<\/td>\n<td>30<\/td>\n<td>26<\/td>\n<td>34<\/td>\n<td>17<\/td>\n<td>19<\/td>\n<td>26<\/td>\n<td>20<\/td>\n<\/tr>\n<tr>\n<td>Weaker Hand<\/td>\n<td>28<\/td>\n<td>14<\/td>\n<td>27<\/td>\n<td>18<\/td>\n<td>17<\/td>\n<td>26<\/td>\n<td>16<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Conduct a hypothesis test to determine whether the mean difference in distances between the children&#8217;s dominant versus weaker hands is significant.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q58390\">Show Answer<\/span><\/p>\n<div id=\"q58390\" class=\"hidden-answer\" style=\"display: none\">\n<p>Record the <strong>differences<\/strong> data. Calculate the differences by subtracting the distances with the weaker hand from the distances with the dominant hand. The data for the differences are: {2, 12, 7, \u20131, 2, 0, 4}. The differences have a normal distribution.<\/p>\n<p>Using the differences data, calculate the sample mean and the sample standard deviation. [latex]\\displaystyle\\overline{{x}}_{{d}}={3.71},{s}_{{d}}={4.5}[\/latex].<\/p>\n<p><strong>Random variable:<\/strong> [latex]\\displaystyle\\overline{{X}}_{{d}}[\/latex] = mean difference in the distances between the hands.<\/p>\n<p><strong>Distribution for the hypothesis test:\u00a0<\/strong><em>t<sub data-redactor-tag=\"sub\">6<\/sub><\/em><\/p>\n<p><em>H<\/em><sub>0<\/sub>: <em>\u03bc<sub data-redactor-tag=\"sub\">d<\/sub><\/em> = 0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0<em>H<\/em><em><sub data-redactor-tag=\"sub\">a<\/sub><\/em>: <em>\u03bc<\/em><em><sub data-redactor-tag=\"sub\">d<\/sub><\/em> \u2260 0<\/p>\n<p><strong>Graph:<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-2135 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/5668\/2021\/07\/01182302\/241d9297afa0ff25a21010d7cb0b1fc9847d0f4b.jpeg\" alt=\"This is a normal distribution curve with mean equal to zero. Both the right and left tails of the curve are shaded. Each tail represents 1\/2(p-value) = 0.0358.\" width=\"487\" height=\"177\" \/><\/p>\n<p><strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value:<\/strong>\u00a0the <em>p<\/em>-value is 0.0716 (using the data directly).<\/p>\n<p>(test statistic = 2.18. <em>p<\/em>-value = 0.0719 using ([latex]{\\overline x} = 3.71, {s_d} = 4.5[\/latex].)<\/p>\n<p><strong>Decision:<\/strong>\u00a0assume <em>\u03b1<\/em> = 0.05. Since <em>\u03b1<\/em> &lt; <em>p<\/em>-value, Do not reject <em>H<sub data-redactor-tag=\"sub\">0<\/sub><\/em>.<\/p>\n<p><strong>Conclusion:<\/strong>\u00a0at the 5% level of significance, from the sample data, there is not sufficient evidence to conclude that there is a difference in the children&#8217;s weaker and dominant hands to push the shot-put.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>try it 3<\/h3>\n<p>Five ball players think they can throw the same distance with their dominant hand (throwing) and off-hand (catching hand). The data were collected and recorded in the table below. Conduct a hypothesis test to determine whether the mean difference in distances between the dominant and off-hand is significant. Test at the 5% level.<\/p>\n<table style=\"border-collapse: collapse; width: 100%; height: 36px;\">\n<thead>\n<tr style=\"height: 12px;\">\n<td class=\"shaded\" style=\"width: 16.6667%; height: 12px;\"><\/td>\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Player 1<\/strong><\/td>\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Player 2<\/strong><\/td>\n<th style=\"width: 16.6667%; height: 12px;\"><strong>Player 3<\/strong><\/th>\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Player 4<\/strong><\/td>\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Player 5<\/strong><\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"height: 12px;\">\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Dominant Hand<\/strong><\/td>\n<td style=\"width: 16.6667%; height: 12px;\">120<\/td>\n<td style=\"width: 16.6667%; height: 12px;\">111<\/td>\n<td style=\"width: 16.6667%; height: 12px;\">135<\/td>\n<td style=\"width: 16.6667%; height: 12px;\">140<\/td>\n<td style=\"width: 16.6667%; height: 12px;\">125<\/td>\n<\/tr>\n<tr style=\"height: 12px;\">\n<td style=\"width: 16.6667%; height: 12px;\"><strong>Off-hand<\/strong><\/td>\n<td style=\"width: 16.6667%; height: 12px;\">105<\/td>\n<td style=\"width: 16.6667%; height: 12px;\">109<\/td>\n<td style=\"width: 16.6667%; height: 12px;\">98<\/td>\n<td style=\"width: 16.6667%; height: 12px;\">111<\/td>\n<td style=\"width: 16.6667%; height: 12px;\">99<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q578994\">Show Answer<\/span><\/p>\n<div id=\"q578994\" class=\"hidden-answer\" style=\"display: none\">\n<p>The <em>p<\/em>-level is 0.0230, so we can reject the null hypothesis. The data show that the players do not throw the same distance with their off-hands as they do with their dominant hands.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-290\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Statistics, Matched or Paired Sample. <strong>Provided by<\/strong>: OpenStax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/openstax.org\/books\/statistics\/pages\/10-4-matched-or-paired-samples-optional\">https:\/\/openstax.org\/books\/statistics\/pages\/10-4-matched-or-paired-samples-optional<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Access for free at https:\/\/openstax.org\/books\/statistics\/pages\/1-introduction<\/li><li>Introductory Statistics. <strong>Authored by<\/strong>: Barbara Illowsky, Susan Dean. <strong>Provided by<\/strong>: OpenStax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/openstax.org\/books\/introductory-statistics\/pages\/1-introduction\">https:\/\/openstax.org\/books\/introductory-statistics\/pages\/1-introduction<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Access for free at https:\/\/openstax.org\/books\/introductory-statistics\/pages\/1-introduction<\/li><\/ul><div class=\"license-attribution-dropdown-subheading\">All rights reserved content<\/div><ul class=\"citation-list\"><li>Z-statistics vs. T-statistics | Inferential statistics | Probability and Statistics | Khan Academy . <strong>Authored by<\/strong>: Khan Academy. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/www.youtube.com\/embed\/5ABpqVSx33I\">https:\/\/www.youtube.com\/embed\/5ABpqVSx33I<\/a>. <strong>License<\/strong>: <em>All Rights Reserved<\/em>. <strong>License Terms<\/strong>: Standard YouTube License<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":169134,"menu_order":17,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Statistics, Matched or Paired Sample\",\"author\":\"\",\"organization\":\"OpenStax\",\"url\":\"https:\/\/openstax.org\/books\/statistics\/pages\/10-4-matched-or-paired-samples-optional\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Access for free at https:\/\/openstax.org\/books\/statistics\/pages\/1-introduction\"},{\"type\":\"copyrighted_video\",\"description\":\"Z-statistics vs. T-statistics | Inferential statistics | Probability and Statistics | Khan Academy 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