{"id":39,"date":"2024-04-03T23:09:24","date_gmt":"2024-04-03T20:09:24","guid":{"rendered":"https:\/\/sisu.ut.ee\/measurement\/7-precision-trueness-accuracy\/"},"modified":"2025-03-26T09:09:00","modified_gmt":"2025-03-26T07:09:00","slug":"7-precision-trueness-accuracy","status":"publish","type":"page","link":"https:\/\/sisu.ut.ee\/measurement\/7-precision-trueness-accuracy\/","title":{"rendered":"7. Precision, trueness, accuracy"},"content":{"rendered":"<p><strong>Brief summary<\/strong>: Interrelations between the different error types (<strong>random<\/strong>, <strong>systematic<\/strong>, <strong>total<\/strong>), their corresponding performance characteristics (<strong>precision<\/strong>, <strong>trueness<\/strong>, <strong>accuracy<\/strong>) and the parameters for quantitatively expressing these performance parameters (<strong>standard deviation<\/strong>, <strong>bias<\/strong>, <strong>measurement uncertainty<\/strong>) are explained in this section.<\/p>\n<p style=\"text-align: center;\"><\/p><div class=\"ratio ratio-16x9 mb-3\"><div class=\"video-placeholder-wrapper video-placeholder-wrapper--16x9\">\n\t\t\t    <div class=\"video-placeholder d-flex justify-content-center align-items-center\">\n\t\t\t        <div class=\"overlay text-white p-2 w-100 text-center d-block justify-content-center align-items-center\">\n\t\t\t            <div>To view third-party content, please accept cookies.<\/div>\n\t\t\t            <button class=\"btn btn-secondary btn-sm mt-1 consent-change\">Change consent<\/button>\n\t\t\t        <\/div>\n\t\t\t    <\/div>\n\t\t\t<\/div>\n<\/div>\n<h4 style=\"text-align: center;\"><strong>Interrelation between the concepts of precision, trueness, accuracy and measurement uncertainty<\/strong><br>\n<a href=\"http:\/\/www.uttv.ee\/naita?id=17824\" target=\"_blank\" rel=\"noopener\">http:\/\/www.uttv.ee\/naita?id=17824<\/a><\/h4>\n<p style=\"text-align: center;\"><a href=\"https:\/\/www.youtube.com\/watch?v=NdDK03f0wew\" target=\"_blank\" rel=\"noopener\">https:\/\/www.youtube.com\/watch?v=NdDK03f0wew<\/a><\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"720\" class=\"wp-image-133 aligncenter\" style=\"width: 650px; height: 366px;\" title=\"scheme7.1.png\" src=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/18\/scheme7.1.png\" alt=\"Interrelations between the different error types\" srcset=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/18\/scheme7.1.png 1280w, https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/18\/scheme7.1-300x169.png 300w, https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/18\/scheme7.1-1024x576.png 1024w, https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/18\/scheme7.1-768x432.png 768w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\"><\/p>\n<p style=\"text-align: center;\"><strong>Scheme 7.1. Interrelations between the different error types, the performance characteristics used to estimate them and the ways of expressing the estimates quantitatively. This type of scheme was originally published in article <\/strong><a title=\"A. Menditto, et al Accred. Qual. Assur. 2007, 12, 45\" href=\"https:\/\/link.springer.com\/article\/10.1007%2Fs00769-006-0191-z\" target=\"_blank\" rel=\"noopener\" data-url=\"https:\/\/link.springer.com\/article\/10.1007%2Fs00769-006-0191-z\">A. Menditto, et al Accred. Qual. Assur. 2007, 12, 45<\/a><strong>.<\/strong><\/p>\n<p style=\"text-align: justify;\">The difference between the measured value and the true value is called error or <em>total<\/em> error (see section 1). This error can be divided into two parts \u2013 <strong>random error<\/strong> (having different magnitude and sign in the case of repeated measurements) and <strong>systematic error<\/strong> (having the same or systematically changing magnitude and sign in the case of repeated measurements). As seen in section 1 errors cannot be known exactly. Therefore instead of errors themselves we operate with <em>estimates<\/em> of errors \u2013 the performance characteristics.<\/p>\n<p style=\"text-align: justify;\">Thus, <strong>trueness<\/strong> is the estimate of the systematic error. For determining trueness we do not need to know the true value but we need to know a <strong>reference value<\/strong>. Reference value (differently from the true value) has uncertainty, but usually a small one. Different types of <strong>precision<\/strong> are estimates of the random error. For obtaining the \u201ctrue\u201d precision we would need to make an infinite number of repeated measurements. There are different types of precision, depending on the conditions under which precision is determined, e.g. repeatability (section 1) and intermediate precision (section 6). Accuracy embraces both trueness and precision and be considered as describing the total error.<\/p>\n<p style=\"text-align: justify;\">These performance characteristics can be quantitatively expressed. <strong>Bias<\/strong> \u2013 difference between the measured value obtained from multiple repeated measurements with the same sample and the reference value \u2013 is the quantitative expression of trueness. <strong>Standard deviation<\/strong> \u2013 again obtained from multiple measurements with the same sample \u2013 is the quantitative expression of precision. These two can be combined into a <strong>measurement uncertainty<\/strong> estimate, which can be regarded as the quantitative expression of accuracy.<\/p>\n<p style=\"text-align: center;\"><a href=\"https:\/\/sisu.ut.ee\/measurement\/self-test-7\/\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-60\" title=\"selftest.png\" src=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/18\/selftest.png\" alt=\"selftest.png\" width=\"104\" height=\"41\"><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Brief summary: Interrelations between the different error types (random, systematic, total), their corresponding performance characteristics (precision, trueness, accuracy) and the parameters for quantitatively expressing these performance parameters (standard deviation, bias, measurement uncertainty) are explained in this section. To view third-party &#8230;<\/p>\n","protected":false},"author":14,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"class_list":["post-39","page","type-page","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/sisu.ut.ee\/measurement\/wp-json\/wp\/v2\/pages\/39","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sisu.ut.ee\/measurement\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sisu.ut.ee\/measurement\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sisu.ut.ee\/measurement\/wp-json\/wp\/v2\/users\/14"}],"replies":[{"embeddable":true,"href":"https:\/\/sisu.ut.ee\/measurement\/wp-json\/wp\/v2\/comments?post=39"}],"version-history":[{"count":3,"href":"https:\/\/sisu.ut.ee\/measurement\/wp-json\/wp\/v2\/pages\/39\/revisions"}],"predecessor-version":[{"id":858,"href":"https:\/\/sisu.ut.ee\/measurement\/wp-json\/wp\/v2\/pages\/39\/revisions\/858"}],"wp:attachment":[{"href":"https:\/\/sisu.ut.ee\/measurement\/wp-json\/wp\/v2\/media?parent=39"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}