{"id":697,"date":"2023-08-25T19:03:43","date_gmt":"2023-08-25T19:03:43","guid":{"rendered":"https:\/\/textbooks.jaykesler.net\/introstats\/?post_type=part&#038;p=697"},"modified":"2023-09-04T16:18:44","modified_gmt":"2023-09-04T16:18:44","slug":"confidence-intervals-with-two-samples","status":"publish","type":"part","link":"https:\/\/textbooks.jaykesler.net\/introstats\/part\/confidence-intervals-with-two-samples\/","title":{"rendered":"Confidence Intervals with Two Samples"},"content":{"raw":"<img class=\"full-width alignnone wp-image-738 size-large\" src=\"https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-1024x683.jpg\" alt=\"Image showing a hillside on fire.\" width=\"1024\" height=\"683\" \/>\r\n<div id=\"3156cbd2-f14e-4bac-bb76-07d69213dfb8\" class=\"introduction\" data-type=\"page\" data-cnxml-to-html-ver=\"2.1.0\">\r\n<div id=\"fs-idm16905488\" class=\"os-figure has-splash\">\r\n<div class=\"os-caption-container\"><span class=\"os-title-label\">Figure <\/span><span class=\"os-number\">7.1<\/span> <span class=\"os-caption\">Fires burning on the Hawaiian islands in 2023.<\/span><\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<div id=\"fs-idp26371136\" class=\"chapter-objectives ui-has-child-title\" data-type=\"note\" data-has-label=\"true\" data-label=\"\"><header>\r\n<h3 class=\"os-title\" data-type=\"title\"><span class=\"os-title-label\">Chapter Objectives<\/span><\/h3>\r\n<\/header><section>\r\n<div class=\"os-note-body\">\r\n<p id=\"element-745\">By the end of this chapter, the student should be able to:<\/p>\r\n\r\n<ul id=\"list6234\">\r\n \t<li>Distinguish between independent and paired\/dependent samples<\/li>\r\n \t<li>Construct confidence intervals for the difference between two population means or proportions<\/li>\r\n \t<li>Describe the pooled standard deviation and the known standard deviation methods<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/section><\/div>\r\nWe have already seen the usefulness of Confidence Intervals when we are trying to estimate a population parameter (mean or proportion). Often times we want to compare a parameter from two different populations. To do this, we can create a confidence interval to estimate the <span style=\"text-decoration: underline;\">difference<\/span> between the two parameters.\r\n\r\n<\/div>\r\n<\/div>\r\n<div>For example, medical researchers may want to know whether a new treatment for colon cancer is effective. They can assign a group of patients to receive the new treatment and another group of patients to receive the old treatment. The researchers might then look at the difference in the <em>proportion<\/em> of patients in each group who went into remission.<\/div>\r\n<div>As another example, the data below lists the sea surface high temperature recorded each month of the years 1960 and 2020.<\/div>\r\n<div>\r\n<table border=\"0\" cellspacing=\"0\">\r\n<tbody>\r\n<tr>\r\n<td align=\"left\" height=\"17\"><\/td>\r\n<td align=\"right\"><strong><span style=\"font-family: Liberation Serif;\">2020<\/span><\/strong><\/td>\r\n<td align=\"right\"><strong><span style=\"font-family: Liberation Serif;\">1960<\/span><\/strong><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>January<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.672<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.016<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>February<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.6215<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0385<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>March<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.6505<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0055<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>April<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.6475<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0315<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>May<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.671<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.022<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>June<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.737<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.037<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>July<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.718<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.061<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>August<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.776<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.05<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>September<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.726<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.0785<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>October<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.705<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0245<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>November<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.6875<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0195<\/span><\/td>\r\n<\/tr>\r\n<tr>\r\n<td align=\"right\" height=\"17\"><strong>December<\/strong><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.7415<\/span><\/td>\r\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.016<\/span><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<div class=\"os-caption-container\"><span class=\"os-caption\">Source: <a href=\"https:\/\/ourworldindata.org\/explorers\/climate-change?facet=none&amp;country=OWID_WRL~ATA~Gulkana+Glacier~Lemon+Creek+Glacier~OWID_NAM~South+Cascade+Glacier~Wolverine+Glacier~Hawaii&amp;Metric=Sea+surface+temperature+anomaly&amp;Long-run+series=false\" target=\"_blank\" rel=\"noopener\">Our World In Data<\/a><\/span><\/div>\r\n<\/div>\r\n<div>We can use a confidence interval to look for a difference between the average high temperatures.<\/div>\r\n<div><\/div>\r\n<div>In this chapter, we will become familiar with the techniques of constructing confidence intervals that look for differences in population parameters such as those in this introduction.<\/div>\r\n<\/div>","rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"full-width alignnone wp-image-738 size-large\" src=\"https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-1024x683.jpg\" alt=\"Image showing a hillside on fire.\" width=\"1024\" height=\"683\" srcset=\"https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-1024x683.jpg 1024w, https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-300x200.jpg 300w, https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-768x512.jpg 768w, https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-1536x1025.jpg 1536w, https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-2048x1366.jpg 2048w, https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-65x43.jpg 65w, https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-225x150.jpg 225w, https:\/\/textbooks.jaykesler.net\/introstats\/wp-content\/uploads\/sites\/2\/2023\/08\/matt-palmer-kbTp7dBzHyY-unsplash-350x233.jpg 350w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/p>\n<div id=\"3156cbd2-f14e-4bac-bb76-07d69213dfb8\" class=\"introduction\" data-type=\"page\" data-cnxml-to-html-ver=\"2.1.0\">\n<div id=\"fs-idm16905488\" class=\"os-figure has-splash\">\n<div class=\"os-caption-container\"><span class=\"os-title-label\">Figure <\/span><span class=\"os-number\">7.1<\/span> <span class=\"os-caption\">Fires burning on the Hawaiian islands in 2023.<\/span><\/div>\n<\/div>\n<div>\n<div>\n<div id=\"fs-idp26371136\" class=\"chapter-objectives ui-has-child-title\" data-type=\"note\" data-has-label=\"true\" data-label=\"\">\n<header>\n<h3 class=\"os-title\" data-type=\"title\"><span class=\"os-title-label\">Chapter Objectives<\/span><\/h3>\n<\/header>\n<section>\n<div class=\"os-note-body\">\n<p id=\"element-745\">By the end of this chapter, the student should be able to:<\/p>\n<ul id=\"list6234\">\n<li>Distinguish between independent and paired\/dependent samples<\/li>\n<li>Construct confidence intervals for the difference between two population means or proportions<\/li>\n<li>Describe the pooled standard deviation and the known standard deviation methods<\/li>\n<\/ul>\n<\/div>\n<\/section>\n<\/div>\n<p>We have already seen the usefulness of Confidence Intervals when we are trying to estimate a population parameter (mean or proportion). Often times we want to compare a parameter from two different populations. To do this, we can create a confidence interval to estimate the <span style=\"text-decoration: underline;\">difference<\/span> between the two parameters.<\/p>\n<\/div>\n<\/div>\n<div>For example, medical researchers may want to know whether a new treatment for colon cancer is effective. They can assign a group of patients to receive the new treatment and another group of patients to receive the old treatment. The researchers might then look at the difference in the <em>proportion<\/em> of patients in each group who went into remission.<\/div>\n<div>As another example, the data below lists the sea surface high temperature recorded each month of the years 1960 and 2020.<\/div>\n<div>\n<table style=\"border-spacing: 0px;\">\n<tbody>\n<tr>\n<td align=\"left\" style=\"height: 17px;\"><\/td>\n<td align=\"right\"><strong><span style=\"font-family: Liberation Serif;\">2020<\/span><\/strong><\/td>\n<td align=\"right\"><strong><span style=\"font-family: Liberation Serif;\">1960<\/span><\/strong><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>January<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.672<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.016<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>February<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.6215<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0385<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>March<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.6505<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0055<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>April<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.6475<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0315<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>May<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.671<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.022<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>June<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.737<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.037<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>July<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.718<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.061<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>August<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.776<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.05<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>September<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.726<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.0785<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>October<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.705<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0245<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>November<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.6875<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">-0.0195<\/span><\/td>\n<\/tr>\n<tr>\n<td align=\"right\" style=\"height: 17px;\"><strong>December<\/strong><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.7415<\/span><\/td>\n<td align=\"right\"><span style=\"font-family: Liberation Serif;\">0.016<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"os-caption-container\"><span class=\"os-caption\">Source: <a href=\"https:\/\/ourworldindata.org\/explorers\/climate-change?facet=none&amp;country=OWID_WRL~ATA~Gulkana+Glacier~Lemon+Creek+Glacier~OWID_NAM~South+Cascade+Glacier~Wolverine+Glacier~Hawaii&amp;Metric=Sea+surface+temperature+anomaly&amp;Long-run+series=false\" target=\"_blank\" rel=\"noopener\">Our World In Data<\/a><\/span><\/div>\n<\/div>\n<div>We can use a confidence interval to look for a difference between the average high temperatures.<\/div>\n<div><\/div>\n<div>In this chapter, we will become familiar with the techniques of constructing confidence intervals that look for differences in population parameters such as those in this introduction.<\/div>\n<\/div>\n","protected":false},"parent":0,"menu_order":9,"template":"","meta":{"pb_part_invisible":null},"contributor":[],"license":[],"class_list":["post-697","part","type-part","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/textbooks.jaykesler.net\/introstats\/wp-json\/pressbooks\/v2\/parts\/697","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/textbooks.jaykesler.net\/introstats\/wp-json\/pressbooks\/v2\/parts"}],"about":[{"href":"https:\/\/textbooks.jaykesler.net\/introstats\/wp-json\/wp\/v2\/types\/part"}],"version-history":[{"count":13,"href":"https:\/\/textbooks.jaykesler.net\/introstats\/wp-json\/pressbooks\/v2\/parts\/697\/revisions"}],"predecessor-version":[{"id":746,"href":"https:\/\/textbooks.jaykesler.net\/introstats\/wp-json\/pressbooks\/v2\/parts\/697\/revisions\/746"}],"wp:attachment":[{"href":"https:\/\/textbooks.jaykesler.net\/introstats\/wp-json\/wp\/v2\/media?parent=697"}],"wp:term":[{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/textbooks.jaykesler.net\/introstats\/wp-json\/wp\/v2\/contributor?post=697"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/textbooks.jaykesler.net\/introstats\/wp-json\/wp\/v2\/license?post=697"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}