{"id":4625,"date":"2026-08-12T15:44:20","date_gmt":"2026-08-12T13:44:20","guid":{"rendered":"https:\/\/ellistat.com\/?post_type=guide-dutilisateur&#038;p=4625"},"modified":"2026-08-12T15:44:20","modified_gmt":"2026-08-12T13:44:20","slug":"prepare-the-data","status":"publish","type":"guide-dutilisateur","link":"https:\/\/ellistat.com\/en\/guide-dutilisateur\/preparer-les-donnees\/","title":{"rendered":"Prepare the data"},"content":{"rendered":"<p class=\"wp-block-paragraph\">The specifications are taken from the&nbsp;<strong>grid<\/strong>&nbsp;of the project. The selector at the top of the page allows you to choose which ones to examine.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Two concepts underpin reading and are worth understanding above all else:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>The sample<\/strong>\u00a0consists of a set of measurements taken together or a rational subset. It forms the basis for control charts.<\/li>\n\n\n\n<li><strong>The Rehearsal<\/strong>\u00a0distinguishes between multiple measurements within the same sample.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This breakdown determines how the variance is calculated\u00a0<strong>short term<\/strong>, which refers to the variation within a sample, as opposed to overall dispersion, which includes variations from one sample to another. This is the key difference between Cp and Pp (see the appendix).<\/p>\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 An arbitrary division into samples distorts this separation. Grouping measurements that were not taken together increases short-term variability and masks trends.<\/p>\n<\/blockquote>","protected":false},"featured_media":0,"menu_order":20,"template":"","meta":{"_acf_changed":true},"menu-guide-dutilisateur":[22],"class_list":["post-4625","guide-dutilisateur","type-guide-dutilisateur","status-publish","hentry","menu-guide-dutilisateur-4-statistiques-descriptives"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.4 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Pr\u00e9parer les donn\u00e9es - Ellistat<\/title>\n<meta name=\"description\" content=\"Comprendre la diff\u00e9rence entre \u00e9chantillon et r\u00e9p\u00e9tition, dispersion court terme et globale : la base pour bien pr\u00e9parer une analyse statistique fiable.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/ellistat.com\/en\/users-guide\/prepare-the-data\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Pr\u00e9parer les donn\u00e9es - 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