{"id":274,"date":"2022-06-16T18:27:14","date_gmt":"2022-06-16T18:27:14","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/alphamodule\/?post_type=chapter&#038;p=274"},"modified":"2022-06-16T19:14:04","modified_gmt":"2022-06-16T19:14:04","slug":"experimental-design-learn-it-1","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/alphamodule\/chapter\/experimental-design-learn-it-1\/","title":{"raw":"Experimental Design: Learn It 1","rendered":"Experimental Design: Learn It 1"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>learning GOALS<\/h3>\r\n<ul>\r\n \t<li>Identify the factor of interest and response factor in an experiment.<\/li>\r\n \t<li>Identify the nuisance factors in an experiment.<\/li>\r\n \t<li>Identify the experimental and control groups in an experiment.<\/li>\r\n \t<li>Recognize random assignment.<\/li>\r\n \t<li>Identify which of two methods of replication was used in an experiment.<\/li>\r\n<\/ul>\r\n<\/div>\r\nExperimental design refers to the structure of an experiment (a specific type of research method). How can the experiment be conducted efficiently, effectively, and responsibly, to return sound results? Researchers must carefully consider several key components of experimental design before any work is done to collect data.\r\n\r\nIn the upcoming activity, you will need to identify the key components of experimental design. We'll take them one by one in the following questions.\r\n<h2>Experimental Design<\/h2>\r\nAn experimental study, or experiment, is a specific method of research that is especially useful for determining cause and effect. Typically, a basic experiment design includes a treatment imposed by the researcher, a comparison between one group that receives the treatment and another group that does not, and random assignment of participants into each group. We\u2019ll explore each of these concepts in more detail below.\r\n\r\nTo help you understand the key components of experimental design, consider this simplified experiment:\r\n\r\n<span style=\"background-color: #ffff99;\">[insert an image of a lake? fish eggs? pH strips?]<\/span>\r\n\r\n<em>An ecologist wants to know if acid rain affects the rate of reproduction for fish in a local lake. The ecologist incubates 1,000 fish eggs in healthy lake water (pH = 6.5) and another 1,000 fish eggs in acidic water (pH = 4.5). The eggs have been randomly assigned to either the healthy lake water group or the acidic water group. The water temperature, amount of dissolved oxygen, and amount and timing of light were kept at optimal levels for both groups. After 14 days, the ecologist counted how many eggs from each group had hatched.<\/em>\r\n\r\nEach of the questions below will ask about aspects of the design present in this experiment.\r\n<div class=\"textbox key-takeaways\">\r\n<h3>question 1<\/h3>\r\nA good experiment always starts with a good research question. For an experiment, the research question is usually about whether one thing causes another. Fill in the blanks below to summarize the ecologist\u2019s research question.\r\n\r\n\u201cDoes ______________________ cause ________________________?\u201d\r\n\r\n[reveal-answer q=\"727621\"]Hint[\/reveal-answer]\r\n[hidden-answer a=\"727621\"]What does the ecologist want to know? What is the specific cause and effect the ecologist is investigating?[\/hidden-answer]\r\n\r\n<\/div>\r\n<h3>Factors<\/h3>\r\nIn an experimental study, the <strong>factor of interest<\/strong> (also known as the <strong>explanatory variable<\/strong> or independent variable) is the factor that the researcher purposely changes or manipulates to see if it impacts a specific outcome. The <strong>treatments<\/strong> are the different levels of the factor of interest (or explanatory variable) you are changing (e.g., no vaccine vs. vaccine).\r\n\r\nThe <strong>response variable<\/strong> (also known as the <strong>dependent variable<\/strong>) is an objective measure of the research question that is measured at the end of an experiment and compared across the different levels of the factor of interest (or explanatory variable).\r\n\r\n<img class=\"alignnone wp-image-1391\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/5738\/2022\/01\/14234115\/Picture192-300x67.jpg\" alt=\"A small flowchart. The first box says &quot;Factor of Interest \/ Explanatory Variable.&quot; There is an arrow beside it labeled &quot;affects&quot; going to the second box, labeled &quot;Response Variable.&quot;\" width=\"1294\" height=\"289\" \/>\r\n\r\nThe <strong>nuisance factors<\/strong> are factors that are kept the same across all levels of the factor or are explicitly controlled in the experimental design. These factors are not of interest in the study but may affect a change in the response variable.\r\n<div class=\"textbox tryit\">\r\n<h3>Video Placement<\/h3>\r\n<span style=\"background-color: #e6daf7;\">[A video briefly describing factor of interest, treatment, response variable, and nuisance factors. This should be no more than a minute long. ]<\/span>\r\n\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Example<\/h3>\r\nSummarize the terminology surrounding factors by answering the questions below.\r\n<ol>\r\n \t<li>The factor of interest is also known as the _________________. Fill in the blank.<\/li>\r\n \t<li>The response variable is also known as the ________________. Fill in the blank.<\/li>\r\n \t<li>What does the researcher purposely change or manipulate to see if it impacts a specific outcome? Choose all that apply\r\n<ol>\r\n \t<li>a) experimental factor<\/li>\r\n \t<li>b) explanatory variable<\/li>\r\n \t<li>c) response factor<\/li>\r\n \t<li>d) factor of interest<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>What are treatments in an experiment?\r\n<ol>\r\n \t<li>a) medicine applied to one set of individuals but not the other<\/li>\r\n \t<li>b)\u00a0the different levels of the factor of interest (or explanatory variable) you are changing<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>What are nuisance factors in an experiment?\r\n<ol>\r\n \t<li>a) types of observational units that are particularly bothersome such as loud talkers<\/li>\r\n \t<li>b) types of factors that researchers are unable to account for in an experiment<\/li>\r\n \t<li>c)\u00a0factors that are kept the same across all levels of the factor or are explicitly controlled in the experimental design<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>What is measured at the end of an experiment and compared across the different levels of the factor of interest?<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"54865\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"54865\"]1. explanatory variable; 2. dependent variable; 3. b and d; 4. b; 5. c; 6. the response variable[\/hidden-answer]\r\n\r\n<\/div>\r\nNow you try. Use the definitions given above to answer Question 2. Remember to view the feedback for your answers to assess your understanding.\r\n<div class=\"textbox key-takeaways\">\r\n<h3>question 2<\/h3>\r\nIdentify the different parts of the experimental design in the previous simplified experiment.\r\n\r\nPart A: What is the factor of interest?\r\n<ol>\r\n \t<li>a) pH level<\/li>\r\n \t<li>b) Temperature<\/li>\r\n \t<li>c) Oxygen level<\/li>\r\n \t<li>d) Amount of light<\/li>\r\n \t<li>e) Timing of light<\/li>\r\n \t<li>f) Incubation duration<\/li>\r\n \t<li>g) Number of eggs hatched<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"344691\"]Hint[\/reveal-answer]\r\n[hidden-answer a=\"344691\"]Which factor did the ecologist purposely change?[\/hidden-answer]\r\n\r\n&nbsp;\r\n\r\nPart B: What is the response variable?\r\n<ol>\r\n \t<li>a) pH<\/li>\r\n \t<li>b) Temperature<\/li>\r\n \t<li>c) Oxygen level<\/li>\r\n \t<li>d) Amount of light<\/li>\r\n \t<li>e) Timing of light<\/li>\r\n \t<li>f)\u00a0 Incubation duration<\/li>\r\n \t<li>g) Number of eggs hatched<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"821608\"]Hint[\/reveal-answer]\r\n[hidden-answer a=\"821608\"]Which factor did the ecologist measure at the end of the study?[\/hidden-answer]\r\n\r\n&nbsp;\r\n\r\nPart C: What are the nuisance factors in the previous experiment? There may be more than one correct answer.\r\n<ol>\r\n \t<li>a) pH<\/li>\r\n \t<li>b) Temperature<\/li>\r\n \t<li>c) Oxygen level<\/li>\r\n \t<li>d) Amount of light<\/li>\r\n \t<li>e) Timing of light<\/li>\r\n \t<li>f) Incubation duration<\/li>\r\n \t<li>g) Number of eggs hatched<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"861184\"]Hint[\/reveal-answer]\r\n[hidden-answer a=\"861184\"]Which factors did the ecologist keep the same for both groups?[\/hidden-answer]\r\n\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>learning GOALS<\/h3>\n<ul>\n<li>Identify the factor of interest and response factor in an experiment.<\/li>\n<li>Identify the nuisance factors in an experiment.<\/li>\n<li>Identify the experimental and control groups in an experiment.<\/li>\n<li>Recognize random assignment.<\/li>\n<li>Identify which of two methods of replication was used in an experiment.<\/li>\n<\/ul>\n<\/div>\n<p>Experimental design refers to the structure of an experiment (a specific type of research method). How can the experiment be conducted efficiently, effectively, and responsibly, to return sound results? Researchers must carefully consider several key components of experimental design before any work is done to collect data.<\/p>\n<p>In the upcoming activity, you will need to identify the key components of experimental design. We&#8217;ll take them one by one in the following questions.<\/p>\n<h2>Experimental Design<\/h2>\n<p>An experimental study, or experiment, is a specific method of research that is especially useful for determining cause and effect. Typically, a basic experiment design includes a treatment imposed by the researcher, a comparison between one group that receives the treatment and another group that does not, and random assignment of participants into each group. We\u2019ll explore each of these concepts in more detail below.<\/p>\n<p>To help you understand the key components of experimental design, consider this simplified experiment:<\/p>\n<p><span style=\"background-color: #ffff99;\">[insert an image of a lake? fish eggs? pH strips?]<\/span><\/p>\n<p><em>An ecologist wants to know if acid rain affects the rate of reproduction for fish in a local lake. The ecologist incubates 1,000 fish eggs in healthy lake water (pH = 6.5) and another 1,000 fish eggs in acidic water (pH = 4.5). The eggs have been randomly assigned to either the healthy lake water group or the acidic water group. The water temperature, amount of dissolved oxygen, and amount and timing of light were kept at optimal levels for both groups. After 14 days, the ecologist counted how many eggs from each group had hatched.<\/em><\/p>\n<p>Each of the questions below will ask about aspects of the design present in this experiment.<\/p>\n<div class=\"textbox key-takeaways\">\n<h3>question 1<\/h3>\n<p>A good experiment always starts with a good research question. For an experiment, the research question is usually about whether one thing causes another. Fill in the blanks below to summarize the ecologist\u2019s research question.<\/p>\n<p>\u201cDoes ______________________ cause ________________________?\u201d<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q727621\">Hint<\/span><\/p>\n<div id=\"q727621\" class=\"hidden-answer\" style=\"display: none\">What does the ecologist want to know? What is the specific cause and effect the ecologist is investigating?<\/div>\n<\/div>\n<\/div>\n<h3>Factors<\/h3>\n<p>In an experimental study, the <strong>factor of interest<\/strong> (also known as the <strong>explanatory variable<\/strong> or independent variable) is the factor that the researcher purposely changes or manipulates to see if it impacts a specific outcome. The <strong>treatments<\/strong> are the different levels of the factor of interest (or explanatory variable) you are changing (e.g., no vaccine vs. vaccine).<\/p>\n<p>The <strong>response variable<\/strong> (also known as the <strong>dependent variable<\/strong>) is an objective measure of the research question that is measured at the end of an experiment and compared across the different levels of the factor of interest (or explanatory variable).<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-1391\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/5738\/2022\/01\/14234115\/Picture192-300x67.jpg\" alt=\"A small flowchart. The first box says &quot;Factor of Interest \/ Explanatory Variable.&quot; There is an arrow beside it labeled &quot;affects&quot; going to the second box, labeled &quot;Response Variable.&quot;\" width=\"1294\" height=\"289\" \/><\/p>\n<p>The <strong>nuisance factors<\/strong> are factors that are kept the same across all levels of the factor or are explicitly controlled in the experimental design. These factors are not of interest in the study but may affect a change in the response variable.<\/p>\n<div class=\"textbox tryit\">\n<h3>Video Placement<\/h3>\n<p><span style=\"background-color: #e6daf7;\">[A video briefly describing factor of interest, treatment, response variable, and nuisance factors. This should be no more than a minute long. ]<\/span><\/p>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Example<\/h3>\n<p>Summarize the terminology surrounding factors by answering the questions below.<\/p>\n<ol>\n<li>The factor of interest is also known as the _________________. Fill in the blank.<\/li>\n<li>The response variable is also known as the ________________. Fill in the blank.<\/li>\n<li>What does the researcher purposely change or manipulate to see if it impacts a specific outcome? Choose all that apply\n<ol>\n<li>a) experimental factor<\/li>\n<li>b) explanatory variable<\/li>\n<li>c) response factor<\/li>\n<li>d) factor of interest<\/li>\n<\/ol>\n<\/li>\n<li>What are treatments in an experiment?\n<ol>\n<li>a) medicine applied to one set of individuals but not the other<\/li>\n<li>b)\u00a0the different levels of the factor of interest (or explanatory variable) you are changing<\/li>\n<\/ol>\n<\/li>\n<li>What are nuisance factors in an experiment?\n<ol>\n<li>a) types of observational units that are particularly bothersome such as loud talkers<\/li>\n<li>b) types of factors that researchers are unable to account for in an experiment<\/li>\n<li>c)\u00a0factors that are kept the same across all levels of the factor or are explicitly controlled in the experimental design<\/li>\n<\/ol>\n<\/li>\n<li>What is measured at the end of an experiment and compared across the different levels of the factor of interest?<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q54865\">Show Answer<\/span><\/p>\n<div id=\"q54865\" class=\"hidden-answer\" style=\"display: none\">1. explanatory variable; 2. dependent variable; 3. b and d; 4. b; 5. c; 6. the response variable<\/div>\n<\/div>\n<\/div>\n<p>Now you try. Use the definitions given above to answer Question 2. Remember to view the feedback for your answers to assess your understanding.<\/p>\n<div class=\"textbox key-takeaways\">\n<h3>question 2<\/h3>\n<p>Identify the different parts of the experimental design in the previous simplified experiment.<\/p>\n<p>Part A: What is the factor of interest?<\/p>\n<ol>\n<li>a) pH level<\/li>\n<li>b) Temperature<\/li>\n<li>c) Oxygen level<\/li>\n<li>d) Amount of light<\/li>\n<li>e) Timing of light<\/li>\n<li>f) Incubation duration<\/li>\n<li>g) Number of eggs hatched<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q344691\">Hint<\/span><\/p>\n<div id=\"q344691\" class=\"hidden-answer\" style=\"display: none\">Which factor did the ecologist purposely change?<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<p>Part B: What is the response variable?<\/p>\n<ol>\n<li>a) pH<\/li>\n<li>b) Temperature<\/li>\n<li>c) Oxygen level<\/li>\n<li>d) Amount of light<\/li>\n<li>e) Timing of light<\/li>\n<li>f)\u00a0 Incubation duration<\/li>\n<li>g) Number of eggs hatched<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q821608\">Hint<\/span><\/p>\n<div id=\"q821608\" class=\"hidden-answer\" style=\"display: none\">Which factor did the ecologist measure at the end of the study?<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<p>Part C: What are the nuisance factors in the previous experiment? There may be more than one correct answer.<\/p>\n<ol>\n<li>a) pH<\/li>\n<li>b) Temperature<\/li>\n<li>c) Oxygen level<\/li>\n<li>d) Amount of light<\/li>\n<li>e) Timing of light<\/li>\n<li>f) Incubation duration<\/li>\n<li>g) Number of eggs hatched<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q861184\">Hint<\/span><\/p>\n<div id=\"q861184\" class=\"hidden-answer\" style=\"display: none\">Which factors did the ecologist keep the same for both groups?<\/div>\n<\/div>\n<\/div>\n","protected":false},"author":17533,"menu_order":17,"template":"","meta":{"_candela_citation":"[]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-274","chapter","type-chapter","status-publish","hentry"],"part":158,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/pressbooks\/v2\/chapters\/274","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/wp\/v2\/users\/17533"}],"version-history":[{"count":4,"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/pressbooks\/v2\/chapters\/274\/revisions"}],"predecessor-version":[{"id":297,"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/pressbooks\/v2\/chapters\/274\/revisions\/297"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/pressbooks\/v2\/parts\/158"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/pressbooks\/v2\/chapters\/274\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/wp\/v2\/media?parent=274"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/pressbooks\/v2\/chapter-type?post=274"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/wp\/v2\/contributor?post=274"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/alphamodule\/wp-json\/wp\/v2\/license?post=274"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}