{"id":481,"date":"2024-10-18T01:57:56","date_gmt":"2024-10-18T01:57:56","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/mat1260\/?post_type=chapter&#038;p=481"},"modified":"2024-12-11T18:35:32","modified_gmt":"2024-12-11T18:35:32","slug":"3-1-explanatory-and-response-variables","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/mat1260\/chapter\/3-1-explanatory-and-response-variables\/","title":{"raw":"3.1: Explanatory and Response Variables","rendered":"3.1: Explanatory and Response Variables"},"content":{"raw":"<div id=\"lobjh\" class=\"\">\r\n\r\nWhile it is fundamentally important to know how to describe the distribution of a single variable, most studies pose research questions that involve exploring the relationship between\u00a0<em class=\"italic\">two<\/em>\u00a0variables using the collected data.\r\n\r\n<\/div>\r\n<p id=\"N10B0F\">Here are a few examples of such research questions with the two variables highlighted:<\/p>\r\n\r\n<div id=\"overviewexamples\" class=\"section\">\r\n<div class=\"sectionContain\">\r\n<h2><span title=\"Quick scroll up\">Examples<\/span><\/h2>\r\n<ol>\r\n \t<li>\r\n<p id=\"N10B1E\">Is there a relationship between\u00a0<em>gender<\/em>\u00a0and\u00a0<em>test scores<\/em>\u00a0on a particular standardized test?<\/p>\r\n<p id=\"N10B27\">Other ways of phrasing the same research question include the following:<\/p>\r\n\r\n<ul>\r\n \t<li>Is performance on the test related to gender?<\/li>\r\n \t<li>Is there a gender effect on test scores?<\/li>\r\n \t<li>Are there differences in test scores between males and females?<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>How is the\u00a0<em>number of calories<\/em>\u00a0in a hot dog related to (or affected by) the\u00a0<em>type of hot dog<\/em>\u00a0(beef, meat or poultry)? In other words, are there differences in the number of calories among the three types of hot dogs?<\/li>\r\n \t<li>Is there a relationship between the\u00a0<em>type of light<\/em>\u00a0a baby sleeps with (no light, night-light, lamp) and whether or not the child develops\u00a0<em>nearsightedness<\/em>?<\/li>\r\n \t<li>Are the\u00a0<em>smoking habits<\/em>\u00a0of a person (yes, no) related to the person\u2019s\u00a0<em>gender<\/em>?<\/li>\r\n \t<li>How well can we predict a student\u2019s freshman year\u00a0<em>GPA<\/em>\u00a0from his\/her\u00a0<em>SAT score<\/em>?<\/li>\r\n \t<li>What is the relationship between driver\u2019s\u00a0<em>age<\/em>\u00a0and sign legibility\u00a0<em>distance<\/em>\u00a0(the maximum distance at which the driver can read a sign)?<\/li>\r\n \t<li>Is there a relationship between the\u00a0<em>time<\/em>\u00a0a person has practiced driving while having a learner\u2019s permit and\u00a0<em>whether or not this person passed the driving test<\/em>?<\/li>\r\n \t<li>Can you predict a person\u2019s\u00a0<em>favorite type of music<\/em>\u00a0(classical, rock, jazz) on the basis of his\/her\u00a0<em>IQ level<\/em>?<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<p id=\"N10B79\">In most studies involving two variables, each of the variables has a role. We distinguish between:<\/p>\r\n\r\n<ul>\r\n \t<li>The\u00a0<em>explanatory<\/em>\u00a0variable (also commonly referred to as the\u00a0<em class=\"bold\">independent variable<\/em>)\u2014the variable that claims to explain, predict, or affect the response; and<\/li>\r\n \t<li>The\u00a0<em>response<\/em>\u00a0variable (also commonly referred to as the\u00a0<em class=\"bold\">dependent variable<\/em>)\u2014the outcome of the study.<\/li>\r\n<\/ul>\r\n<p id=\"N10B93\">Typically, the explanatory (or independent) variable is denoted by\u00a0<em>X<\/em>, while the response (or dependent) variable is denoted by\u00a0<em>Y<\/em>.<\/p>\r\n\r\n<h2><span title=\"Quick scroll up\">Explanatory and Response Variables<\/span><\/h2>\r\n<div id=\"N10B9C\" class=\"section\">\r\n<div class=\"sectionContain\">\r\n<p id=\"N10BA4\">In this course, we use the terms\u00a0<em class=\"italic\">explanatory<\/em>\u00a0and\u00a0<em class=\"italic\">response<\/em>\u00a0variables instead of\u00a0<em class=\"italic\">independent<\/em>\u00a0and\u00a0<em class=\"italic\">dependent<\/em>\u00a0variables.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<p id=\"N10BB9\">Now, let\u2019s go back to some of the examples and classify the two relevant variables according to their roles in the study.<\/p>\r\n\r\n<div class=\"examplewrap\">\r\n<div class=\"exHead\">\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Example 1<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nWe want to explore whether the outcome of the study\u2014the score on a test\u2014is affected by the test-taker\u2019s gender.\r\n<div class=\"example clearfix\">\r\n<table class=\"wbtable\">\r\n<tbody>\r\n<tr class=\"e\">\r\n<td>Therefore:<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><em>Gender<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable<\/td>\r\n<\/tr>\r\n<tr class=\"e\">\r\n<td><em>Test score<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Example 2<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<div class=\"examplewrap\">\r\n<div class=\"exHead\">In this study, we explore whether the nearsightedness of a person can be explained by the type of light that person slept with as a baby.<\/div>\r\n<\/div>\r\n<div class=\"examplewrap\">\r\n<div class=\"example clearfix\">\r\n<table class=\"wbtable\">\r\n<tbody>\r\n<tr class=\"e\">\r\n<td>Therefore:<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><em>Light type<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable<\/td>\r\n<\/tr>\r\n<tr class=\"e\">\r\n<td><em>Nearsightedness<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"examplewrap\">\r\n<div class=\"example clearfix\">\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Example 3<\/h3>\r\n<\/header>\r\n<div>\r\n<p id=\"N10C15\">Here we are examining whether a student\u2019s SAT score is a good predictor for the student\u2019s GPA freshman year.<\/p>\r\n\r\n<table class=\"wbtable\">\r\n<tbody>\r\n<tr class=\"e\">\r\n<td>Therefore:<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><em>SAT score<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable<\/td>\r\n<\/tr>\r\n<tr class=\"e\">\r\n<td><em>GPA of freshman year<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"examplewrap\">\r\n<div class=\"exHead\">\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Example 4<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nHere we are examining whether a person\u2019s outcome on the driving test (pass\/fail) can be explained by the length of time this person has practiced driving prior to the test.\r\n<div class=\"example clearfix\">\r\n<table class=\"wbtable\">\r\n<tbody>\r\n<tr class=\"e\">\r\n<td>Therefore:<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><em>Time<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable<\/td>\r\n<\/tr>\r\n<tr class=\"e\">\r\n<td><em>Driving test outcome<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"actContain\">\r\n<div class=\"activity flash\">\r\n<div class=\"flash_obj asx testFlash mark_flash\">\r\n<div class=\"page 2963083\">\r\n<div class=\"question ddfb\">\r\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Many Students Wonder...<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<div class=\"inquiry\">\r\n<div><strong><em>Question:\u00a0<\/em><\/strong>Is the role classification of variables always clear? In other words, is it always clear which of the variables is the explanatory and which is the response?<\/div>\r\n<div><\/div>\r\n<div class=\"answer\"><strong><em>Answer:\u00a0<\/em><\/strong>No. There are studies in which the role classification is not really clear. This mainly happens in cases when both variables are categorical or both are quantitative. An example is a study that explores the relationship between students' SAT Math and SAT Verbal scores. In cases like this, any classification choice would be fine (as long as it is consistent throughout the analysis).<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<p id=\"N10B18\">If we further classify each of the two relevant variables according to\u00a0<em>type<\/em>\u00a0(categorical or quantitative), we get the following four possibilities for\u00a0<em>role-type classification<\/em>:<\/p>\r\n\r\n<ol>\r\n \t<li>Categorical explanatory and quantitative response<\/li>\r\n \t<li>Categorical explanatory and categorical response<\/li>\r\n \t<li>Quantitative explanatory and quantitative response<\/li>\r\n \t<li>Quantitative explanatory and categorical response<\/li>\r\n<\/ol>\r\n<p id=\"N10B30\">This role-type classification can be summarized and easily visualized in the following table (note that the explanatory variable is always listed first):<\/p>\r\n<span class=\"imagewrap\"><span class=\"image\"><img id=\"_i_0\" class=\"img-responsive popimg aligncenter\" title=\"It is possible for any type of explanatory variable to be paired with any type of response variable. The possible pairings are: Categorical Explanatory \u2192 Categorical Response (C\u2192C), Categorical Explanatory \u2192 Quantitative Response (C\u2192Q), Quantitative Explanatory \u2192 Categorical Response (Q\u2192C), and Quantitative Explanatory \u2192 Quantitative Response (Q\u2192Q)\" src=\"https:\/\/oli.cmu.edu\/repository\/webcontent\/72712ec00a0001dc418a87e73e8ebb77\/_u2_summarizing_data\/_m2_examining_relationships\/webcontent\/relationships_overview1.gif\" alt=\"It is possible for any type of explanatory variable to be paired with any type of response variable. The possible pairings are: Categorical Explanatory \u2192 Categorical Response (C\u2192C), Categorical Explanatory \u2192 Quantitative Response (C\u2192Q), Quantitative Explanatory \u2192 Categorical Response (Q\u2192C), and Quantitative Explanatory \u2192 Quantitative Response (Q\u2192Q)\" \/><\/span><\/span>\r\n<p id=\"N10B39\">This role-type classification serves as the infrastructure for this entire section. In each of the four cases, different statistical tools (displays and numerical measures) should be used to explore the relationship between the two variables. This suggests the following important principle:<\/p>\r\n\r\n<table id=\"N10B3C_bx\" class=\"theorem labeled\">\r\n<thead>\r\n<tr>\r\n<th>Principle<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td>\r\n<div class=\"theorem\">\r\n<div class=\"statement\">\r\n<p id=\"N10B40\">When confronted with a research question that involves exploring the relationship between two variables, the first and most crucial step is to determine which of the four cases represents the data structure of the problem. In other words, the first step should be classifying the two relevant variables according to their role and type, and only then can we determine what statistical tools should be used to analyze them.<\/p>\r\n\r\n<\/div>\r\n<\/div><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<p id=\"N10B44\">Now let\u2019s go back to our examples and determine which of the four cases represents the data structure of each:<\/p>\r\n\r\n<div class=\"examplewrap\">\r\n<div class=\"exHead\">\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Example 1<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<div class=\"example clearfix\">\r\n<div>\r\n<table class=\"wbtable\">\r\n<tbody>\r\n<tr class=\"e\">\r\n<td><em>Gender<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable, and it is\u00a0<em>categorical<\/em>.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><em>Test score<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable, and it is\u00a0<em>quantitative<\/em>.<\/td>\r\n<\/tr>\r\n<tr class=\"e\">\r\n<td>Therefore, this is an example of\u00a0<em>case C\u2192Q<\/em>.<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"examplewrap\">\r\n<div class=\"exHead\">\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Example 2<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<div class=\"example clearfix\">\r\n<div>\r\n<table class=\"wbtable\">\r\n<tbody>\r\n<tr class=\"e\">\r\n<td><em>Light Type<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable, and it is\u00a0<em>categorical<\/em>.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><em>Nearsightedness<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable, and it is\u00a0<em>categorical<\/em>.<\/td>\r\n<\/tr>\r\n<tr class=\"e\">\r\n<td>Therefore, this is an example of\u00a0<em>case C\u2192C<\/em>.<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"examplewrap\">\r\n<div class=\"exHead\">\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Example 3<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<div class=\"example clearfix\">\r\n<div>\r\n<table class=\"wbtable\">\r\n<tbody>\r\n<tr class=\"e\">\r\n<td><em>SAT Score<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable, and it is\u00a0<em>quantitative<\/em>.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><em>GPA of Freshman Year<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable, and it is\u00a0<em>quantitative<\/em>.<\/td>\r\n<\/tr>\r\n<tr class=\"e\">\r\n<td>Therefore, this is an example of\u00a0<em>case Q\u2192Q<\/em>.<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"examplewrap\">\r\n<div class=\"exHead\">\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Example 4<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<div class=\"example clearfix\">\r\n<div>\r\n<table class=\"wbtable\">\r\n<tbody>\r\n<tr class=\"e\">\r\n<td><em>Time<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable, and it is\u00a0<em>quantitative<\/em>.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><em>Driving Test Outcome<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable, and it is\u00a0<em>categorical<\/em>.<\/td>\r\n<\/tr>\r\n<tr class=\"e\">\r\n<td>Therefore, this is an example of\u00a0<em>case Q\u2192C<\/em>.<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"asx\">\r\n<div id=\"du1_m2_roletype2_tutor1\" class=\"activitywrap purpose learnbydoing flash\">\r\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Did I get this?<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<p id=\"N10C35\">In the following three problem, you are presented with a brief description of a study involving two variables. Based on the role-type classification of the two variables, you are asked to determine which of the four cases represents the data structure of the problem.<\/p>\r\n<p id=\"N10C38\">For your convenience, here again is the role-type classification table:<\/p>\r\n<span class=\"imagewrap\"><span class=\"image\"><img id=\"_i_1\" class=\"img-responsive popimg aligncenter\" title=\" Categorical Explanatory \u2192 Categorical Response (C\u2192C), Categorical Explanatory \u2192 Quantitative Response (C\u2192Q), Quantitative Explanatory \u2192 Categorical Response (Q\u2192C), Quantitative Explanatory \u2192 Quantitative Response (Q\u2192Q)\" src=\"https:\/\/oli.cmu.edu\/repository\/webcontent\/72712ec00a0001dc418a87e73e8ebb77\/_u2_summarizing_data\/_m2_examining_relationships\/webcontent\/relationships_overview1.gif\" alt=\" Categorical Explanatory \u2192 Categorical Response (C\u2192C), Categorical Explanatory \u2192 Quantitative Response (C\u2192Q), Quantitative Explanatory \u2192 Categorical Response (Q\u2192C), Quantitative Explanatory \u2192 Quantitative Response (Q\u2192Q)\" \/><\/span><\/span>\r\n\r\n[h5p id=\"41\"]\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>","rendered":"<div id=\"lobjh\" class=\"\">\n<p>While it is fundamentally important to know how to describe the distribution of a single variable, most studies pose research questions that involve exploring the relationship between\u00a0<em class=\"italic\">two<\/em>\u00a0variables using the collected data.<\/p>\n<\/div>\n<p id=\"N10B0F\">Here are a few examples of such research questions with the two variables highlighted:<\/p>\n<div id=\"overviewexamples\" class=\"section\">\n<div class=\"sectionContain\">\n<h2><span title=\"Quick scroll up\">Examples<\/span><\/h2>\n<ol>\n<li>\n<p id=\"N10B1E\">Is there a relationship between\u00a0<em>gender<\/em>\u00a0and\u00a0<em>test scores<\/em>\u00a0on a particular standardized test?<\/p>\n<p id=\"N10B27\">Other ways of phrasing the same research question include the following:<\/p>\n<ul>\n<li>Is performance on the test related to gender?<\/li>\n<li>Is there a gender effect on test scores?<\/li>\n<li>Are there differences in test scores between males and females?<\/li>\n<\/ul>\n<\/li>\n<li>How is the\u00a0<em>number of calories<\/em>\u00a0in a hot dog related to (or affected by) the\u00a0<em>type of hot dog<\/em>\u00a0(beef, meat or poultry)? In other words, are there differences in the number of calories among the three types of hot dogs?<\/li>\n<li>Is there a relationship between the\u00a0<em>type of light<\/em>\u00a0a baby sleeps with (no light, night-light, lamp) and whether or not the child develops\u00a0<em>nearsightedness<\/em>?<\/li>\n<li>Are the\u00a0<em>smoking habits<\/em>\u00a0of a person (yes, no) related to the person\u2019s\u00a0<em>gender<\/em>?<\/li>\n<li>How well can we predict a student\u2019s freshman year\u00a0<em>GPA<\/em>\u00a0from his\/her\u00a0<em>SAT score<\/em>?<\/li>\n<li>What is the relationship between driver\u2019s\u00a0<em>age<\/em>\u00a0and sign legibility\u00a0<em>distance<\/em>\u00a0(the maximum distance at which the driver can read a sign)?<\/li>\n<li>Is there a relationship between the\u00a0<em>time<\/em>\u00a0a person has practiced driving while having a learner\u2019s permit and\u00a0<em>whether or not this person passed the driving test<\/em>?<\/li>\n<li>Can you predict a person\u2019s\u00a0<em>favorite type of music<\/em>\u00a0(classical, rock, jazz) on the basis of his\/her\u00a0<em>IQ level<\/em>?<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<p id=\"N10B79\">In most studies involving two variables, each of the variables has a role. We distinguish between:<\/p>\n<ul>\n<li>The\u00a0<em>explanatory<\/em>\u00a0variable (also commonly referred to as the\u00a0<em class=\"bold\">independent variable<\/em>)\u2014the variable that claims to explain, predict, or affect the response; and<\/li>\n<li>The\u00a0<em>response<\/em>\u00a0variable (also commonly referred to as the\u00a0<em class=\"bold\">dependent variable<\/em>)\u2014the outcome of the study.<\/li>\n<\/ul>\n<p id=\"N10B93\">Typically, the explanatory (or independent) variable is denoted by\u00a0<em>X<\/em>, while the response (or dependent) variable is denoted by\u00a0<em>Y<\/em>.<\/p>\n<h2><span title=\"Quick scroll up\">Explanatory and Response Variables<\/span><\/h2>\n<div id=\"N10B9C\" class=\"section\">\n<div class=\"sectionContain\">\n<p id=\"N10BA4\">In this course, we use the terms\u00a0<em class=\"italic\">explanatory<\/em>\u00a0and\u00a0<em class=\"italic\">response<\/em>\u00a0variables instead of\u00a0<em class=\"italic\">independent<\/em>\u00a0and\u00a0<em class=\"italic\">dependent<\/em>\u00a0variables.<\/p>\n<\/div>\n<\/div>\n<p id=\"N10BB9\">Now, let\u2019s go back to some of the examples and classify the two relevant variables according to their roles in the study.<\/p>\n<div class=\"examplewrap\">\n<div class=\"exHead\">\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Example 1<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<p>We want to explore whether the outcome of the study\u2014the score on a test\u2014is affected by the test-taker\u2019s gender.<\/p>\n<div class=\"example clearfix\">\n<table class=\"wbtable\">\n<tbody>\n<tr class=\"e\">\n<td>Therefore:<\/td>\n<\/tr>\n<tr>\n<td><em>Gender<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable<\/td>\n<\/tr>\n<tr class=\"e\">\n<td><em>Test score<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Example 2<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<div class=\"examplewrap\">\n<div class=\"exHead\">In this study, we explore whether the nearsightedness of a person can be explained by the type of light that person slept with as a baby.<\/div>\n<\/div>\n<div class=\"examplewrap\">\n<div class=\"example clearfix\">\n<table class=\"wbtable\">\n<tbody>\n<tr class=\"e\">\n<td>Therefore:<\/td>\n<\/tr>\n<tr>\n<td><em>Light type<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable<\/td>\n<\/tr>\n<tr class=\"e\">\n<td><em>Nearsightedness<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"examplewrap\">\n<div class=\"example clearfix\">\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Example 3<\/h3>\n<\/header>\n<div>\n<p id=\"N10C15\">Here we are examining whether a student\u2019s SAT score is a good predictor for the student\u2019s GPA freshman year.<\/p>\n<table class=\"wbtable\">\n<tbody>\n<tr class=\"e\">\n<td>Therefore:<\/td>\n<\/tr>\n<tr>\n<td><em>SAT score<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable<\/td>\n<\/tr>\n<tr class=\"e\">\n<td><em>GPA of freshman year<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"examplewrap\">\n<div class=\"exHead\">\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Example 4<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<p>Here we are examining whether a person\u2019s outcome on the driving test (pass\/fail) can be explained by the length of time this person has practiced driving prior to the test.<\/p>\n<div class=\"example clearfix\">\n<table class=\"wbtable\">\n<tbody>\n<tr class=\"e\">\n<td>Therefore:<\/td>\n<\/tr>\n<tr>\n<td><em>Time<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable<\/td>\n<\/tr>\n<tr class=\"e\">\n<td><em>Driving test outcome<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"actContain\">\n<div class=\"activity flash\">\n<div class=\"flash_obj asx testFlash mark_flash\">\n<div class=\"page 2963083\">\n<div class=\"question ddfb\">\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Many Students Wonder&#8230;<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<div class=\"inquiry\">\n<div><strong><em>Question:\u00a0<\/em><\/strong>Is the role classification of variables always clear? In other words, is it always clear which of the variables is the explanatory and which is the response?<\/div>\n<div><\/div>\n<div class=\"answer\"><strong><em>Answer:\u00a0<\/em><\/strong>No. There are studies in which the role classification is not really clear. This mainly happens in cases when both variables are categorical or both are quantitative. An example is a study that explores the relationship between students&#8217; SAT Math and SAT Verbal scores. In cases like this, any classification choice would be fine (as long as it is consistent throughout the analysis).<\/div>\n<\/div>\n<\/div>\n<\/div>\n<p id=\"N10B18\">If we further classify each of the two relevant variables according to\u00a0<em>type<\/em>\u00a0(categorical or quantitative), we get the following four possibilities for\u00a0<em>role-type classification<\/em>:<\/p>\n<ol>\n<li>Categorical explanatory and quantitative response<\/li>\n<li>Categorical explanatory and categorical response<\/li>\n<li>Quantitative explanatory and quantitative response<\/li>\n<li>Quantitative explanatory and categorical response<\/li>\n<\/ol>\n<p id=\"N10B30\">This role-type classification can be summarized and easily visualized in the following table (note that the explanatory variable is always listed first):<\/p>\n<p><span class=\"imagewrap\"><span class=\"image\"><img decoding=\"async\" id=\"_i_0\" class=\"img-responsive popimg aligncenter\" title=\"It is possible for any type of explanatory variable to be paired with any type of response variable. The possible pairings are: Categorical Explanatory \u2192 Categorical Response (C\u2192C), Categorical Explanatory \u2192 Quantitative Response (C\u2192Q), Quantitative Explanatory \u2192 Categorical Response (Q\u2192C), and Quantitative Explanatory \u2192 Quantitative Response (Q\u2192Q)\" src=\"https:\/\/oli.cmu.edu\/repository\/webcontent\/72712ec00a0001dc418a87e73e8ebb77\/_u2_summarizing_data\/_m2_examining_relationships\/webcontent\/relationships_overview1.gif\" alt=\"It is possible for any type of explanatory variable to be paired with any type of response variable. The possible pairings are: Categorical Explanatory \u2192 Categorical Response (C\u2192C), Categorical Explanatory \u2192 Quantitative Response (C\u2192Q), Quantitative Explanatory \u2192 Categorical Response (Q\u2192C), and Quantitative Explanatory \u2192 Quantitative Response (Q\u2192Q)\" \/><\/span><\/span><\/p>\n<p id=\"N10B39\">This role-type classification serves as the infrastructure for this entire section. In each of the four cases, different statistical tools (displays and numerical measures) should be used to explore the relationship between the two variables. This suggests the following important principle:<\/p>\n<table id=\"N10B3C_bx\" class=\"theorem labeled\">\n<thead>\n<tr>\n<th>Principle<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\n<div class=\"theorem\">\n<div class=\"statement\">\n<p id=\"N10B40\">When confronted with a research question that involves exploring the relationship between two variables, the first and most crucial step is to determine which of the four cases represents the data structure of the problem. In other words, the first step should be classifying the two relevant variables according to their role and type, and only then can we determine what statistical tools should be used to analyze them.<\/p>\n<\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p id=\"N10B44\">Now let\u2019s go back to our examples and determine which of the four cases represents the data structure of each:<\/p>\n<div class=\"examplewrap\">\n<div class=\"exHead\">\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Example 1<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<div class=\"example clearfix\">\n<div>\n<table class=\"wbtable\">\n<tbody>\n<tr class=\"e\">\n<td><em>Gender<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable, and it is\u00a0<em>categorical<\/em>.<\/td>\n<\/tr>\n<tr>\n<td><em>Test score<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable, and it is\u00a0<em>quantitative<\/em>.<\/td>\n<\/tr>\n<tr class=\"e\">\n<td>Therefore, this is an example of\u00a0<em>case C\u2192Q<\/em>.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"examplewrap\">\n<div class=\"exHead\">\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Example 2<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<div class=\"example clearfix\">\n<div>\n<table class=\"wbtable\">\n<tbody>\n<tr class=\"e\">\n<td><em>Light Type<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable, and it is\u00a0<em>categorical<\/em>.<\/td>\n<\/tr>\n<tr>\n<td><em>Nearsightedness<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable, and it is\u00a0<em>categorical<\/em>.<\/td>\n<\/tr>\n<tr class=\"e\">\n<td>Therefore, this is an example of\u00a0<em>case C\u2192C<\/em>.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"examplewrap\">\n<div class=\"exHead\">\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Example 3<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<div class=\"example clearfix\">\n<div>\n<table class=\"wbtable\">\n<tbody>\n<tr class=\"e\">\n<td><em>SAT Score<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable, and it is\u00a0<em>quantitative<\/em>.<\/td>\n<\/tr>\n<tr>\n<td><em>GPA of Freshman Year<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable, and it is\u00a0<em>quantitative<\/em>.<\/td>\n<\/tr>\n<tr class=\"e\">\n<td>Therefore, this is an example of\u00a0<em>case Q\u2192Q<\/em>.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"examplewrap\">\n<div class=\"exHead\">\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Example 4<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<div class=\"example clearfix\">\n<div>\n<table class=\"wbtable\">\n<tbody>\n<tr class=\"e\">\n<td><em>Time<\/em>\u00a0is the\u00a0<em>explanatory<\/em>\u00a0variable, and it is\u00a0<em>quantitative<\/em>.<\/td>\n<\/tr>\n<tr>\n<td><em>Driving Test Outcome<\/em>\u00a0is the\u00a0<em>response<\/em>\u00a0variable, and it is\u00a0<em>categorical<\/em>.<\/td>\n<\/tr>\n<tr class=\"e\">\n<td>Therefore, this is an example of\u00a0<em>case Q\u2192C<\/em>.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"asx\">\n<div id=\"du1_m2_roletype2_tutor1\" class=\"activitywrap purpose learnbydoing flash\">\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Did I get this?<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<p id=\"N10C35\">In the following three problem, you are presented with a brief description of a study involving two variables. Based on the role-type classification of the two variables, you are asked to determine which of the four cases represents the data structure of the problem.<\/p>\n<p id=\"N10C38\">For your convenience, here again is the role-type classification table:<\/p>\n<p><span class=\"imagewrap\"><span class=\"image\"><img decoding=\"async\" id=\"_i_1\" class=\"img-responsive popimg aligncenter\" title=\"Categorical Explanatory \u2192 Categorical Response (C\u2192C), Categorical Explanatory \u2192 Quantitative Response (C\u2192Q), Quantitative Explanatory \u2192 Categorical Response (Q\u2192C), Quantitative Explanatory \u2192 Quantitative Response (Q\u2192Q)\" src=\"https:\/\/oli.cmu.edu\/repository\/webcontent\/72712ec00a0001dc418a87e73e8ebb77\/_u2_summarizing_data\/_m2_examining_relationships\/webcontent\/relationships_overview1.gif\" alt=\"Categorical Explanatory \u2192 Categorical Response (C\u2192C), Categorical Explanatory \u2192 Quantitative Response (C\u2192Q), Quantitative Explanatory \u2192 Categorical Response (Q\u2192C), Quantitative Explanatory \u2192 Quantitative Response (Q\u2192Q)\" \/><\/span><\/span><\/p>\n<div id=\"h5p-41\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-41\" class=\"h5p-iframe\" data-content-id=\"41\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.1 Did I get this? 1\"><\/iframe><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"author":150,"menu_order":2,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[48],"contributor":[],"license":[],"class_list":["post-481","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":417,"_links":{"self":[{"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/pressbooks\/v2\/chapters\/481","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/wp\/v2\/users\/150"}],"version-history":[{"count":9,"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/pressbooks\/v2\/chapters\/481\/revisions"}],"predecessor-version":[{"id":846,"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/pressbooks\/v2\/chapters\/481\/revisions\/846"}],"part":[{"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/pressbooks\/v2\/parts\/417"}],"metadata":[{"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/pressbooks\/v2\/chapters\/481\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/wp\/v2\/media?parent=481"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/pressbooks\/v2\/chapter-type?post=481"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/wp\/v2\/contributor?post=481"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/mat1260\/wp-json\/wp\/v2\/license?post=481"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}