{"id":388,"date":"2016-04-21T22:43:39","date_gmt":"2016-04-21T22:43:39","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/introstats1xmaster\/?post_type=chapter&#038;p=388"},"modified":"2022-04-14T19:37:07","modified_gmt":"2022-04-14T19:37:07","slug":"matched-or-paired-samples","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/frontrange-introstats1\/chapter\/matched-or-paired-samples\/","title":{"raw":"Matched or Paired Samples","rendered":"Matched or 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 and interpret hypothesis tests for matched or paired samples<\/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-t 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}=\\frac{{\\overline{{x}}_{{d}}-{\\mu}_{{d}}}}{{{(\\frac{{s}_{{d}}}{\\sqrt{{n}}})}}}[\/latex]\r\n<h4>Using a Excel<\/h4>\r\nWe will use the Excel function =<strong>T.TEST\u00a0<\/strong>to find our p-value.\u00a0 The\u00a0<strong>T.TEST<\/strong> function takes raw paired data and r<span style=\"font-size: 1rem; text-align: initial;\">eturns the probability associated with a Student's t-Test. Use T.TEST to determine whether two samples are likely to have come from the same two underlying populations that have the same mean.\u00a0\u00a0The\u00a0<strong>T.TEST<\/strong> function has the following s<\/span><span style=\"font-size: 1rem; text-align: initial;\">yntax:<\/span>\r\n<div id=\"f1Body\" class=\"excel colorful\" data-bi-area=\"content\">\r\n<div id=\"f1Asset\" class=\"grd \" role=\"group\" aria-label=\"T.TEST function\" data-bi-area=\"\" data-videotitle=\"View on web\" data-assetid=\"d4e08ec3-c545-485f-962e-276f7cbed055\" data-bi-areaposition=\"\" data-bi-formnm=\"\">\r\n<div class=\"row\">\r\n<div class=\"col-5-5\"><article class=\"ocpArticleContent\"><section class=\"ocpSection\" role=\"region\" aria-label=\"Syntax\">\r\n<p style=\"text-align: center;\">T.TEST(array1,array2,tails,type)<\/p>\r\nThe T.TEST function syntax has the following arguments:\r\n<ul>\r\n \t<li><b class=\"ocpRunInHead\">Array1<\/b>\u00a0\u00a0\u00a0\u00a0 Required. The first data set.<\/li>\r\n \t<li><b class=\"ocpRunInHead\">Array2<\/b>\u00a0\u00a0\u00a0\u00a0 Required. The second data set.<\/li>\r\n \t<li><b class=\"ocpRunInHead\">Tails<\/b>\u00a0\u00a0\u00a0\u00a0 Required. Specifies the number of distribution tails. If tails = 1, T.TEST uses the one-tailed distribution. If tails = 2, T.TEST uses the two-tailed distribution.<\/li>\r\n \t<li><b class=\"ocpRunInHead\">Type<\/b>\u00a0\u00a0\u00a0\u00a0 Required. The kind of t-Test to perform.<\/li>\r\n<\/ul>\r\n<\/section><\/article><\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\nhttps:\/\/www.youtube.com\/embed\/5ABpqVSx33I\r\n<div class=\"textbox exercises\">\r\n<h3>Example<\/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<strong>Solution:<\/strong>\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 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-t distribution: <\/strong><em>p<\/em>-value = 0.0095 (In Excel, use =T.TEST(array1, array2, 1, 1)=0.0095)\r\n\r\n<strong>Graph:<\/strong>\r\n\r\n<img src=\"https:\/\/textimgs.s3.amazonaws.com\/DE\/stats\/0qxo-o8euu37i#fixme#fixme#fixme\" 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.\" \/>\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> Since <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> At 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<\/div>\r\n\r\n<hr \/>\r\n\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<hr \/>\r\n\r\n<h4>Using a Calculator<\/h4>\r\n<ul>\r\n \t<li>Use your list of differences as the data.<\/li>\r\n \t<li>Press<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 class=\"textbox key-takeaways\">\r\n<h3>try it<\/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=\"157475\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"157475\"]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.[\/hidden-answer]\r\n\r\n<\/div>\r\n<h3><\/h3>\r\n<div class=\"textbox exercises\">\r\n<h3>Example<\/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\r\n<strong>Solution:<\/strong>\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\r\n<em>Note: 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.<\/em>\r\n\r\n<hr \/>\r\n\r\nUsing the difference data, this becomes a test of a single mean.\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\u00a0\u00a0<\/sub>(there are 4 - 1 or 3 degrees of freedom).<\/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 src=\"https:\/\/textimgs.s3.amazonaws.com\/DE\/stats\/r5cp-hgeuu37i#fixme#fixme#fixme\" 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.\" \/>\r\n\r\n<strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value:<\/strong> The <em>p<\/em>-value is 0.2150\r\n\r\n<strong>Decision:<\/strong> If 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: <\/strong>At 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<\/div>\r\n\r\n<hr \/>\r\n\r\n<div class=\"textbox key-takeaways\">\r\n<h3>try it<\/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=\"205494\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"205494\"]\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<h3><\/h3>\r\n<div class=\"textbox exercises\">\r\n<h3>Example<\/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<strong>Solution:<\/strong>\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:<\/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 <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 src=\"https:\/\/textimgs.s3.amazonaws.com\/DE\/stats\/dw92-qleuu37i#fixme#fixme#fixme\" 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.\" \/>\r\n\r\n<strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value:<\/strong> The <em>p<\/em>-value is 0.0716 (using the data directly).\r\n\r\n<strong>Decision:<\/strong> Assume <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> At 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<\/div>\r\n<h3><\/h3>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>try it<\/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>\r\n<thead>\r\n<tr>\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<th>Player 5<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td>Dominant Hand<\/td>\r\n<td>120<\/td>\r\n<td>111<\/td>\r\n<td>135<\/td>\r\n<td>140<\/td>\r\n<td>125<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>Off-hand<\/td>\r\n<td>105<\/td>\r\n<td>109<\/td>\r\n<td>98<\/td>\r\n<td>111<\/td>\r\n<td>99<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n[reveal-answer q=\"162350\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"162350\"]\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>\r\n\r\n<hr \/>\r\n\r\n<h2>Concept Review<\/h2>\r\nA hypothesis test for matched or paired samples (t-test) has these characteristics:\r\n<ul>\r\n \t<li>Test the differences by subtracting one measurement from the other measurement<\/li>\r\n \t<li>Random Variable: [latex]\\displaystyle\\overline{{x}}_{{d}}[\/latex] = mean of the differences<\/li>\r\n \t<li>Distribution: Student's-t distribution with <em>n<\/em> \u2013 1 degrees of freedom<\/li>\r\n \t<li>If the number of differences is small (less than 30), the differences must follow a normal distribution.<\/li>\r\n \t<li>Two samples are drawn from the same set of objects.<\/li>\r\n \t<li>Samples are dependent.<\/li>\r\n<\/ul>\r\n<div class=\"textbox shaded\">\r\n<h2><span style=\"background-color: #ffff00;\">Summary of Requirements:<\/span><\/h2>\r\n<ul>\r\n \t<li>The sample is a simple random sample of matched pairs<\/li>\r\n \t<li>The samples are dependent.<\/li>\r\n \t<li>Either the sample size is at least 30 (n <span style=\"text-decoration: underline;\">&gt;<\/span> 30) pairs or the sample is from a normally distributed population.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<h2>Formula Review<\/h2>\r\nTest Statistic (<em>t<\/em>-score):\u00a0[latex]\\displaystyle{t}=\\frac{{\\overline{{x}}_{{d}}-{\\mu}_{{d}}}}{{{(\\frac{{s}_{{d}}}{\\sqrt{{n}}})}}}[\/latex]\r\n\r\nwhere: [latex]\\displaystyle\\overline{{x}}_{{d}}[\/latex] is the mean of the sample differences. <em>\u03bc<\/em><sub>d<\/sub> is the mean of the population differences. <em>s<sub data-redactor-tag=\"sub\">d<\/sub><\/em> is the sample standard deviation of the differences. <em>n<\/em> is the sample size.\r\n\r\nUse Excel function T.TEST to find the p-value.","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<section>\n<ul>\n<li>Conduct and interpret hypothesis tests for matched or paired samples<\/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-t 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}=\\frac{{\\overline{{x}}_{{d}}-{\\mu}_{{d}}}}{{{(\\frac{{s}_{{d}}}{\\sqrt{{n}}})}}}[\/latex]<\/p>\n<h4>Using a Excel<\/h4>\n<p>We will use the Excel function =<strong>T.TEST\u00a0<\/strong>to find our p-value.\u00a0 The\u00a0<strong>T.TEST<\/strong> function takes raw paired data and r<span style=\"font-size: 1rem; text-align: initial;\">eturns the probability associated with a Student&#8217;s t-Test. Use T.TEST to determine whether two samples are likely to have come from the same two underlying populations that have the same mean.\u00a0\u00a0The\u00a0<strong>T.TEST<\/strong> function has the following s<\/span><span style=\"font-size: 1rem; text-align: initial;\">yntax:<\/span><\/p>\n<div id=\"f1Body\" class=\"excel colorful\" data-bi-area=\"content\">\n<div id=\"f1Asset\" class=\"grd\" role=\"group\" aria-label=\"T.TEST function\" data-bi-area=\"\" data-videotitle=\"View on web\" data-assetid=\"d4e08ec3-c545-485f-962e-276f7cbed055\" data-bi-areaposition=\"\" data-bi-formnm=\"\">\n<div class=\"row\">\n<div class=\"col-5-5\">\n<article class=\"ocpArticleContent\">\n<section class=\"ocpSection\" role=\"region\" aria-label=\"Syntax\">\n<p style=\"text-align: center;\">T.TEST(array1,array2,tails,type)<\/p>\n<p>The T.TEST function syntax has the following arguments:<\/p>\n<ul>\n<li><b class=\"ocpRunInHead\">Array1<\/b>\u00a0\u00a0\u00a0\u00a0 Required. The first data set.<\/li>\n<li><b class=\"ocpRunInHead\">Array2<\/b>\u00a0\u00a0\u00a0\u00a0 Required. The second data set.<\/li>\n<li><b class=\"ocpRunInHead\">Tails<\/b>\u00a0\u00a0\u00a0\u00a0 Required. Specifies the number of distribution tails. If tails = 1, T.TEST uses the one-tailed distribution. If tails = 2, T.TEST uses the two-tailed distribution.<\/li>\n<li><b class=\"ocpRunInHead\">Type<\/b>\u00a0\u00a0\u00a0\u00a0 Required. The kind of t-Test to perform.<\/li>\n<\/ul>\n<\/section>\n<\/article>\n<\/div>\n<\/div>\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<\/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<p><strong>Solution:<\/strong><\/p>\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 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-t distribution: <\/strong><em>p<\/em>-value = 0.0095 (In Excel, use =T.TEST(array1, array2, 1, 1)=0.0095)<\/p>\n<p><strong>Graph:<\/strong><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/textimgs.s3.amazonaws.com\/DE\/stats\/0qxo-o8euu37i#fixme#fixme#fixme\" 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.\" \/><\/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> Since <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> At 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<hr \/>\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<hr \/>\n<h4>Using a Calculator<\/h4>\n<ul>\n<li>Use your list of differences as the data.<\/li>\n<li>Press<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 class=\"textbox key-takeaways\">\n<h3>try it<\/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=\"q157475\">Show Answer<\/span><\/p>\n<div id=\"q157475\" class=\"hidden-answer\" style=\"display: none\">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.<\/div>\n<\/div>\n<\/div>\n<h3><\/h3>\n<div class=\"textbox exercises\">\n<h3>Example<\/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<p><strong>Solution:<\/strong><\/p>\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<p><em>Note: 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.<\/em><\/p>\n<hr \/>\n<p>Using the difference data, this becomes a test of a single mean.<\/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\u00a0\u00a0<\/sub>(there are 4 &#8211; 1 or 3 degrees of freedom).<\/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 decoding=\"async\" src=\"https:\/\/textimgs.s3.amazonaws.com\/DE\/stats\/r5cp-hgeuu37i#fixme#fixme#fixme\" 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.\" \/><\/p>\n<p><strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value:<\/strong> The <em>p<\/em>-value is 0.2150<\/p>\n<p><strong>Decision:<\/strong> If 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: <\/strong>At 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<hr \/>\n<div class=\"textbox key-takeaways\">\n<h3>try it<\/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=\"q205494\">Show Answer<\/span><\/p>\n<div id=\"q205494\" 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<h3><\/h3>\n<div class=\"textbox exercises\">\n<h3>Example<\/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<p><strong>Solution:<\/strong><\/p>\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:<\/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 <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 decoding=\"async\" src=\"https:\/\/textimgs.s3.amazonaws.com\/DE\/stats\/dw92-qleuu37i#fixme#fixme#fixme\" 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.\" \/><\/p>\n<p><strong>Calculate the <em data-redactor-tag=\"em\">p<\/em>-value:<\/strong> The <em>p<\/em>-value is 0.0716 (using the data directly).<\/p>\n<p><strong>Decision:<\/strong> Assume <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> At 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<h3><\/h3>\n<div class=\"textbox key-takeaways\">\n<h3>try it<\/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>\n<thead>\n<tr>\n<th>Player 1<\/th>\n<th>Player 2<\/th>\n<th>Player 3<\/th>\n<th>Player 4<\/th>\n<th>Player 5<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Dominant Hand<\/td>\n<td>120<\/td>\n<td>111<\/td>\n<td>135<\/td>\n<td>140<\/td>\n<td>125<\/td>\n<\/tr>\n<tr>\n<td>Off-hand<\/td>\n<td>105<\/td>\n<td>109<\/td>\n<td>98<\/td>\n<td>111<\/td>\n<td>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=\"q162350\">Show Answer<\/span><\/p>\n<div id=\"q162350\" 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<hr \/>\n<h2>Concept Review<\/h2>\n<p>A hypothesis test for matched or paired samples (t-test) has these characteristics:<\/p>\n<ul>\n<li>Test the differences by subtracting one measurement from the other measurement<\/li>\n<li>Random Variable: [latex]\\displaystyle\\overline{{x}}_{{d}}[\/latex] = mean of the differences<\/li>\n<li>Distribution: Student&#8217;s-t distribution with <em>n<\/em> \u2013 1 degrees of freedom<\/li>\n<li>If the number of differences is small (less than 30), the differences must follow a normal distribution.<\/li>\n<li>Two samples are drawn from the same set of objects.<\/li>\n<li>Samples are dependent.<\/li>\n<\/ul>\n<div class=\"textbox shaded\">\n<h2><span style=\"background-color: #ffff00;\">Summary of Requirements:<\/span><\/h2>\n<ul>\n<li>The sample is a simple random sample of matched pairs<\/li>\n<li>The samples are dependent.<\/li>\n<li>Either the sample size is at least 30 (n <span style=\"text-decoration: underline;\">&gt;<\/span> 30) pairs or the sample is from a normally distributed population.<\/li>\n<\/ul>\n<\/div>\n<h2>Formula Review<\/h2>\n<p>Test Statistic (<em>t<\/em>-score):\u00a0[latex]\\displaystyle{t}=\\frac{{\\overline{{x}}_{{d}}-{\\mu}_{{d}}}}{{{(\\frac{{s}_{{d}}}{\\sqrt{{n}}})}}}[\/latex]<\/p>\n<p>where: [latex]\\displaystyle\\overline{{x}}_{{d}}[\/latex] is the mean of the sample differences. <em>\u03bc<\/em><sub>d<\/sub> is the mean of the population differences. <em>s<sub data-redactor-tag=\"sub\">d<\/sub><\/em> is the sample standard deviation of the differences. <em>n<\/em> is the sample size.<\/p>\n<p>Use Excel function T.TEST to find the p-value.<\/p>\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-388\">\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>OpenStax, Statistics, Matched or Paired Sample. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"\"><\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li>Introductory Statistics . <strong>Authored by<\/strong>: Barbara Illowski, Susan Dean. <strong>Provided by<\/strong>: Open Stax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/30189442-6998-4686-ac05-ed152b91b9de@17.44\">http:\/\/cnx.org\/contents\/30189442-6998-4686-ac05-ed152b91b9de@17.44<\/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>: Download for free at http:\/\/cnx.org\/contents\/30189442-6998-4686-ac05-ed152b91b9de@17.44<\/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":21,"menu_order":6,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"OpenStax, Statistics, Matched or Paired Sample\",\"author\":\"\",\"organization\":\"\",\"url\":\"Download for free at 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