{"id":6958,"date":"2026-04-01T11:16:41","date_gmt":"2026-04-01T09:16:41","guid":{"rendered":"https:\/\/mediconomics.com\/?post_type=glossary&#038;p=6958"},"modified":"2026-07-13T19:09:27","modified_gmt":"2026-07-13T17:09:27","slug":"statistical-power","status":"publish","type":"glossary","link":"https:\/\/mediconomics.com\/en\/glossar\/statistical-power\/","title":{"rendered":"Statistical Power"},"content":{"rendered":"<p>Statistical power is the probability with which a statistical test correctly detects a genuinely existing effect \u2013 that is, rejects the null hypothesis (H\u2080) when it is in fact false. Power = 1 \u2212 \u03b2, where \u03b2 denotes the probability of a Type II error (a false negative finding, i.e. failure to detect a true effect).<\/p>\n<p>In clinical research, a power of at least 80% (\u03b2 \u2264 0.20) is usually targeted, and for pivotal registration trials often 90% (\u03b2 \u2264 0.10). Power depends on four factors: the significance level (\u03b1), the expected effect size (e.g. difference in means), the variability of the measured variable (standard deviation) and the sample size (n). Higher power requires \u2013 for the same \u03b1 and the same variability \u2013 a larger sample size.<\/p>\n<p>Sample size calculation is a central task in study design and must be documented in the study protocol. Insufficient power leads to so-called underpowered studies, which fail to reach significance despite a true effect being present. For CROs, correct sample size calculation \u2013 taking dropout rates and adjustments for multiple testing into account \u2013 is a critical biostatistical task. Regulatory reference: ICH E9.<\/p>\n<p><a href=\"https:\/\/mediconomics.com\/en\/glossary\/\">Back to overview<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Statistical power is the probability with which a statistical test correctly detects a genuinely existing effect \u2013 that is, rejects the null hypothesis (H\u2080) when it is in fact false. Power = 1 \u2212 \u03b2, where \u03b2 denotes the probability of a Type II error (a false negative finding, i.e. failure to detect a true [&hellip;]<\/p>\n","protected":false},"author":10,"featured_media":0,"parent":0,"template":"","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"glossary-cat":[],"class_list":["post-6958","glossary","type-glossary","status-publish","hentry"],"acf":[],"related_terms":"","external_url":"","internal_reference_id":"","_links":{"self":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6958","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/types\/glossary"}],"author":[{"embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/users\/10"}],"version-history":[{"count":1,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6958\/revisions"}],"predecessor-version":[{"id":6959,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6958\/revisions\/6959"}],"wp:attachment":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/media?parent=6958"}],"wp:term":[{"taxonomy":"glossary-cat","embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary-cat?post=6958"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}