{"id":4577,"date":"2026-08-11T11:48:19","date_gmt":"2026-08-11T09:48:19","guid":{"rendered":"https:\/\/ellistat.com\/?post_type=guide-dutilisateur&#038;p=4577"},"modified":"2026-08-11T11:52:03","modified_gmt":"2026-08-11T09:52:03","slug":"the-principle-of-what-a-text-says-and-what-it-doesnt-say","status":"publish","type":"guide-dutilisateur","link":"https:\/\/ellistat.com\/en\/guide-dutilisateur\/le-principe-ce-que-dit-un-text-et-ce-quil-ne-dit-pas\/","title":{"rendered":"The Principle: What a Test Tells Us\u2014and What It Doesn't"},"content":{"rendered":"<p class=\"wp-block-paragraph\">Every test compares two hypotheses:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>H0<\/strong>, the null hypothesis: there is no difference. This is the default hypothesis\u2014the one we seek to refute.<\/li>\n\n\n\n<li><strong>H1<\/strong>, the alternative hypothesis: there is a difference.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The test calculates the&nbsp;<strong>p-value<\/strong>&nbsp;: the probability of observing a difference at least as large as yours&nbsp;<strong>if H0 were true<\/strong>. A low p-value makes it unlikely that the result is due to chance, and we reject H0.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The\u00a0<strong>alpha risk<\/strong>\u00a0is the threshold you set for yourself, traditionally 5:1 or 3:1. This is the risk of reporting a difference that doesn't exist.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ellistat <a href=\"https:\/\/ellistat.com\/en\/data-analysis-solutions\/\" data-type=\"page\" data-id=\"905\">Data Analysis<\/a> classifies the conclusion into four levels, using a color-coding system:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><td><strong>p-value<\/strong><\/td><td><strong>Conclusion<\/strong><\/td><\/tr><\/thead><tbody><tr><td>p \u2264 0.01<\/td><td>Very significant<\/td><\/tr><tr><td>0.01 &lt; p \u2264 0.05<\/td><td>Significant<\/td><\/tr><tr><td>0.05 &lt; p \u2264 0.1<\/td><td>Significant limit<\/td><\/tr><tr><td>p &gt; 0.1<\/td><td>Not significant<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\u26a0\ufe0f\u00a0<strong>\u00abNot significant\u00bb does not mean \"equal.\".<\/strong>\u00a0This means that your data isn't sufficient to draw a conclusion. With five measurements per group, a truly significant difference may still be statistically insignificant; the test doesn't have the power to detect it. That is precisely what the input is for\u00a0<strong>Power<\/strong>.<\/p>\n<\/blockquote>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\ud83d\udca1 Conversely, a tiny difference becomes significant when dealing with very large sample sizes.&nbsp;<strong>\"Significant\" does not mean \"important.\".<\/strong>&nbsp;Always consider the magnitude of the difference in addition to the p-value: the statistic tells us whether the difference is real, while the engineer determines whether it matters.<\/p>\n<\/blockquote>","protected":false},"featured_media":0,"menu_order":20,"template":"","meta":{"_acf_changed":true},"menu-guide-dutilisateur":[23],"class_list":["post-4577","guide-dutilisateur","type-guide-dutilisateur","status-publish","hentry","menu-guide-dutilisateur-5-statistiques-inferentielles"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.2 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Le principe : ce que dit un test et ce qu&#039;il ne dit pas - 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