{"id":11646,"date":"2019-12-25T11:47:05","date_gmt":"2019-12-25T09:47:05","guid":{"rendered":"https:\/\/www.datanovia.com\/en\/?post_type=dt_courses&#038;p=11646"},"modified":"2019-12-26T17:32:50","modified_gmt":"2019-12-26T15:32:50","slug":"t-test-essentials-definition-formula-and-calculation","status":"publish","type":"dt_courses","link":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/","title":{"rendered":"T-Test Essentials: Definition, Formula and Calculation"},"content":{"rendered":"<div id=\"rdoc\">\n<h2>Course description<\/h2>\n<p>The <strong>t-test<\/strong> can be defined as a statistical test used to compare two means. This guide provide multiple tutorials describing the different types of t-test, including:<\/p>\n<ul>\n<li><em>one-sample t-tests<\/em>. Compares one-sample mean to a know standard mean.<\/li>\n<li><em>independent samples t-tests: Student\u2019s t-test and Welch\u2019s t-test<\/em>. Compares two independent groups<\/li>\n<li><em>paired samples t-test<\/em>. Compares two related samples.<\/li>\n<\/ul>\n<p>You will learn the <em>t-test formula<\/em> and how to:<\/p>\n<ul>\n<li><strong>Compute the different t-tests in R<\/strong><\/li>\n<li><strong>Check t-test assumptions<\/strong><\/li>\n<li><strong>Calculate and report t-test effect size<\/strong> using <em>Cohen\u2019s d<\/em>.<\/li>\n<\/ul>\n<p>Contents:<\/p>\n<div id=\"TOC\">\n<ul>\n<li><a href=\"#prerequisites\">Prerequisites<\/a><\/li>\n<li><a href=\"#examples-of-r-codes\">Examples of R codes<\/a><\/li>\n<\/ul>\n<\/div>\n<div class='dt-sc-hr-invisible-medium  '><\/div>\n<div class='dt-sc-ico-content type1'><div class='custom-icon' ><a href='https:\/\/www.datanovia.com\/en\/product\/practical-statistics-in-r-for-comparing-groups-numerical-variables\/' target='_blank'><span class='fa fa-book'><\/span><\/a><\/div><h4><a href='https:\/\/www.datanovia.com\/en\/product\/practical-statistics-in-r-for-comparing-groups-numerical-variables\/' target='_blank'> Related Book <\/a><\/h4>Practical Statistics in R II - Comparing Groups: Numerical Variables<\/div>\n<div class='dt-sc-hr-invisible-medium  '><\/div>\n<div id=\"prerequisites\" class=\"section level2\">\n<h2>Prerequisites<\/h2>\n<p>Make sure you have installed the following R packages:<\/p>\n<ul>\n<li><code>tidyverse<\/code> for data manipulation and visualization<\/li>\n<li><code>ggpubr<\/code> for creating easily publication ready plots<\/li>\n<li><code>rstatix<\/code> provides pipe-friendly R functions for easy statistical analyses.<\/li>\n<li><code>datarium<\/code>: contains required data sets for this chapter.<\/li>\n<\/ul>\n<p>Start by loading the following required packages:<\/p>\n<pre class=\"r\"><code>library(tidyverse)\r\nlibrary(ggpubr)\r\nlibrary(rstatix)<\/code><\/pre>\n<\/div>\n<div id=\"examples-of-r-codes\" class=\"section level2\">\n<h2>Examples of R codes<\/h2>\n<p>Comparing two independent groups:<\/p>\n<pre class=\"r\"><code># Data preparation\r\ndata(\"genderweight\", package = \"datarium\")\r\nhead(genderweight, 3)<\/code><\/pre>\n<pre><code>## # A tibble: 3 x 3\r\n##   id    group weight\r\n##   &lt;fct&gt; &lt;fct&gt;  &lt;dbl&gt;\r\n## 1 1     F       61.6\r\n## 2 2     F       64.6\r\n## 3 3     F       66.2<\/code><\/pre>\n<pre class=\"r\"><code># Statistical test\r\nstat.test &lt;- genderweight %&gt;% \r\n  t_test(weight ~ group) %&gt;%\r\n  add_significance()\r\nstat.test<\/code><\/pre>\n<pre><code>## # A tibble: 1 x 9\r\n##   .y.    group1 group2    n1    n2 statistic    df        p p.signif\r\n##   &lt;chr&gt;  &lt;chr&gt;  &lt;chr&gt;  &lt;int&gt; &lt;int&gt;     &lt;dbl&gt; &lt;dbl&gt;    &lt;dbl&gt; &lt;chr&gt;   \r\n## 1 weight F      M         20    20     -20.8  26.9 4.30e-18 ****<\/code><\/pre>\n<pre class=\"r\"><code># Visualization: \r\n# Create a box-plot\r\nbxp &lt;- ggboxplot(\r\n  genderweight, x = \"group\", y = \"weight\", \r\n  ylab = \"Weight\", xlab = \"Groups\", add = \"jitter\"\r\n  )\r\n# Add p-value and significance levels\r\nstat.test &lt;- stat.test %&gt;% add_xy_position(x = \"group\")\r\nbxp + \r\n  stat_pvalue_manual(stat.test, tip.length = 0) +\r\n  labs(subtitle = get_test_label(stat.test, detailed = TRUE))<\/code><\/pre>\n<p><img decoding=\"async\" src=\"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/dn-tutorials\/r-statistics-2-comparing-groups-means\/figures\/068-t-test-definition-two-sample-box-plot-with-p-values-1.png\" width=\"412.8\" \/><\/p>\n<\/div>\n<\/div>\n<p><!--end rdoc--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Course description The t-test can be defined as a statistical test used to compare two means. This guide provide multiple tutorials describing the different types of t-test, including: one-sample t-tests. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":8934,"menu_order":0,"comment_status":"open","ping_status":"closed","template":"","class_list":["post-11646","dt_courses","type-dt_courses","status-publish","has-post-thumbnail","hentry","course_category-basic-statistics","course_category-biostatistics","course_category-comparing-means"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v25.2 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>T-Test Essentials: Definition, Formula and Calculation - Best Ref - Datanovia<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"T-Test Essentials: Definition, Formula and Calculation - Best Ref - Datanovia\" \/>\n<meta property=\"og:description\" content=\"Course description The t-test can be defined as a statistical test used to compare two means. This guide provide multiple tutorials describing the different types of t-test, including: one-sample t-tests. [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/\" \/>\n<meta property=\"og:site_name\" content=\"Datanovia\" \/>\n<meta property=\"article:modified_time\" content=\"2019-12-26T15:32:50+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2019\/05\/X50521810_793192461020700_1878562830630780928_n.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1024\" \/>\n\t<meta property=\"og:image:height\" content=\"512\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/\",\"url\":\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/\",\"name\":\"T-Test Essentials: Definition, Formula and Calculation - Best Ref - Datanovia\",\"isPartOf\":{\"@id\":\"https:\/\/www.datanovia.com\/en\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2019\/05\/X50521810_793192461020700_1878562830630780928_n.jpg\",\"datePublished\":\"2019-12-25T09:47:05+00:00\",\"dateModified\":\"2019-12-26T15:32:50+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#primaryimage\",\"url\":\"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2019\/05\/X50521810_793192461020700_1878562830630780928_n.jpg\",\"contentUrl\":\"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2019\/05\/X50521810_793192461020700_1878562830630780928_n.jpg\",\"width\":1024,\"height\":512},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.datanovia.com\/en\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Courses\",\"item\":\"https:\/\/www.datanovia.com\/en\/courses\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"T-Test Essentials: Definition, Formula and Calculation\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.datanovia.com\/en\/#website\",\"url\":\"https:\/\/www.datanovia.com\/en\/\",\"name\":\"Datanovia\",\"description\":\"Data Mining and Statistics for Decision Support\",\"publisher\":{\"@id\":\"https:\/\/www.datanovia.com\/en\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.datanovia.com\/en\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.datanovia.com\/en\/#organization\",\"name\":\"Datanovia\",\"url\":\"https:\/\/www.datanovia.com\/en\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.datanovia.com\/en\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2018\/09\/datanovia-logo.png\",\"contentUrl\":\"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2018\/09\/datanovia-logo.png\",\"width\":98,\"height\":99,\"caption\":\"Datanovia\"},\"image\":{\"@id\":\"https:\/\/www.datanovia.com\/en\/#\/schema\/logo\/image\/\"}}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"T-Test Essentials: Definition, Formula and Calculation - Best Ref - Datanovia","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/","og_locale":"en_US","og_type":"article","og_title":"T-Test Essentials: Definition, Formula and Calculation - Best Ref - Datanovia","og_description":"Course description The t-test can be defined as a statistical test used to compare two means. This guide provide multiple tutorials describing the different types of t-test, including: one-sample t-tests. [&hellip;]","og_url":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/","og_site_name":"Datanovia","article_modified_time":"2019-12-26T15:32:50+00:00","og_image":[{"width":1024,"height":512,"url":"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2019\/05\/X50521810_793192461020700_1878562830630780928_n.jpg","type":"image\/jpeg"}],"twitter_card":"summary_large_image","twitter_misc":{"Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/","url":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/","name":"T-Test Essentials: Definition, Formula and Calculation - Best Ref - Datanovia","isPartOf":{"@id":"https:\/\/www.datanovia.com\/en\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#primaryimage"},"image":{"@id":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#primaryimage"},"thumbnailUrl":"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2019\/05\/X50521810_793192461020700_1878562830630780928_n.jpg","datePublished":"2019-12-25T09:47:05+00:00","dateModified":"2019-12-26T15:32:50+00:00","breadcrumb":{"@id":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#primaryimage","url":"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2019\/05\/X50521810_793192461020700_1878562830630780928_n.jpg","contentUrl":"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2019\/05\/X50521810_793192461020700_1878562830630780928_n.jpg","width":1024,"height":512},{"@type":"BreadcrumbList","@id":"https:\/\/www.datanovia.com\/en\/courses\/t-test-essentials-definition-formula-and-calculation\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.datanovia.com\/en\/"},{"@type":"ListItem","position":2,"name":"Courses","item":"https:\/\/www.datanovia.com\/en\/courses\/"},{"@type":"ListItem","position":3,"name":"T-Test Essentials: Definition, Formula and Calculation"}]},{"@type":"WebSite","@id":"https:\/\/www.datanovia.com\/en\/#website","url":"https:\/\/www.datanovia.com\/en\/","name":"Datanovia","description":"Data Mining and Statistics for Decision Support","publisher":{"@id":"https:\/\/www.datanovia.com\/en\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.datanovia.com\/en\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.datanovia.com\/en\/#organization","name":"Datanovia","url":"https:\/\/www.datanovia.com\/en\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.datanovia.com\/en\/#\/schema\/logo\/image\/","url":"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2018\/09\/datanovia-logo.png","contentUrl":"https:\/\/www.datanovia.com\/en\/wp-content\/uploads\/2018\/09\/datanovia-logo.png","width":98,"height":99,"caption":"Datanovia"},"image":{"@id":"https:\/\/www.datanovia.com\/en\/#\/schema\/logo\/image\/"}}]}},"multi-rating":{"mr_rating_results":[{"adjusted_star_result":5,"star_result":5,"total_max_option_value":5,"adjusted_score_result":5,"score_result":5,"percentage_result":100,"adjusted_percentage_result":100,"count":1,"post_id":11646}]},"_links":{"self":[{"href":"https:\/\/www.datanovia.com\/en\/wp-json\/wp\/v2\/dt_courses\/11646","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.datanovia.com\/en\/wp-json\/wp\/v2\/dt_courses"}],"about":[{"href":"https:\/\/www.datanovia.com\/en\/wp-json\/wp\/v2\/types\/dt_courses"}],"author":[{"embeddable":true,"href":"https:\/\/www.datanovia.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.datanovia.com\/en\/wp-json\/wp\/v2\/comments?post=11646"}],"version-history":[{"count":0,"href":"https:\/\/www.datanovia.com\/en\/wp-json\/wp\/v2\/dt_courses\/11646\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.datanovia.com\/en\/wp-json\/wp\/v2\/media\/8934"}],"wp:attachment":[{"href":"https:\/\/www.datanovia.com\/en\/wp-json\/wp\/v2\/media?parent=11646"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}