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  <title>Error</title>
  <link rel="self" href="https://calvalportal.ceos.org/web/guest/cal/val-wiki/-/wiki/668236" />
  <subtitle>Error</subtitle>
  <id>https://calvalportal.ceos.org/web/guest/cal/val-wiki/-/wiki/668236</id>
  <updated>2026-04-15T12:53:32Z</updated>
  <dc:date>2026-04-15T12:53:32Z</dc:date>
  <entry>
    <title>Error 1.0</title>
    <link rel="alternate" href="https://calvalportal.ceos.org/web/guest/cal/val-wiki/-/wiki/668236/Error?_com_liferay_wiki_web_portlet_WikiPortlet_version=1.0" />
    <author>
      <name>Paolo Registration Test</name>
    </author>
    <id>https://calvalportal.ceos.org/web/guest/cal/val-wiki/-/wiki/668236/Error?_com_liferay_wiki_web_portlet_WikiPortlet_version=1.0</id>
    <updated>2020-01-16T11:02:00Z</updated>
    <published>2020-01-16T11:02:00Z</published>
    <summary type="html">&lt;p&gt; &lt;strong&gt;Definition&lt;/strong&gt;&lt;/p&gt;&lt;p&gt; &lt;span style="font-size: 8pt;"&gt;(1)measurement error: measured quantity value minus a reference quantity value&lt;/span&gt;&lt;/p&gt;&lt;div&gt; NOTE &lt;span class="diff-html-removed" id="removed-diff-0" previous="first-diff" changeId="removed-diff-0" next="added-diff-0"&gt;1  &lt;/span&gt;&lt;span class="diff-html-added" id="added-diff-0" previous="removed-diff-0" changeId="added-diff-0" next="removed-diff-1"&gt;1 &lt;/span&gt;The concept of ‘measurement error’ can be used both&lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-removed" previous="added-diff-0" changeId="removed-diff-1" next="removed-diff-2"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-1" previous="added-diff-0" changeId="removed-diff-1" next="removed-diff-2"&gt; &lt;/span&gt;&lt;/div&gt;&lt;div&gt; a) when there is a single reference quantity value to refer to, which occurs if a calibration is made by&lt;/div&gt;&lt;div&gt; means of a measurement standard with a measured quantity value having a negligible&lt;/div&gt;&lt;div&gt; measurement uncertainty or if a conventional quantity value is given, in which case the measurement error is known, and&lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-removed" previous="removed-diff-1" changeId="removed-diff-2" next="removed-diff-3"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-2" previous="removed-diff-1" changeId="removed-diff-2" next="removed-diff-3"&gt; &lt;/span&gt;&lt;/div&gt;&lt;div&gt; b) if a measurand is supposed to be represented by a unique true quantity value or a set of true quantity values of negligible range, in which case the measurement error is not known.&lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-removed" previous="removed-diff-2" changeId="removed-diff-3" next="removed-diff-4"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-3" previous="removed-diff-2" changeId="removed-diff-3" next="removed-diff-4"&gt; &lt;/span&gt;&lt;/div&gt;&lt;div&gt; NOTE &lt;span class="diff-html-removed" id="removed-diff-4" previous="removed-diff-3" changeId="removed-diff-4" next="added-diff-1"&gt;2  &lt;/span&gt;&lt;span class="diff-html-added" id="added-diff-1" previous="removed-diff-4" changeId="added-diff-1" next="removed-diff-5"&gt;2 &lt;/span&gt;Measurement error should not be confused with production error or mistake. &lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-removed" previous="added-diff-1" changeId="removed-diff-5" next="removed-diff-6"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-5" previous="added-diff-1" changeId="removed-diff-5" next="removed-diff-6"&gt; &lt;/span&gt;&lt;/div&gt;&lt;div&gt; (2) difference of quantity value obtained by measurement and true value of the measurand&lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-removed" previous="removed-diff-5" changeId="removed-diff-6" next="removed-diff-7"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-6" previous="removed-diff-5" changeId="removed-diff-6" next="removed-diff-7"&gt; &lt;/span&gt;&lt;/div&gt;&lt;div&gt; (3) difference of forecast value and a, estimate of the true value&lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-removed" previous="removed-diff-6" changeId="removed-diff-7" next="removed-diff-8"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-7" previous="removed-diff-6" changeId="removed-diff-7" next="removed-diff-8"&gt; &lt;/span&gt;&lt;/div&gt;&lt;div&gt; Note: (1) and (2) refer to measurement error, while (3) refers to a forecast error&lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-removed" previous="removed-diff-7" changeId="removed-diff-8" next="removed-diff-9"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-8" previous="removed-diff-7" changeId="removed-diff-8" next="removed-diff-9"&gt; &lt;/span&gt;&lt;/div&gt;&lt;div&gt; (4) result of a measurement minus a true value of the measurand&lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-removed" previous="removed-diff-8" changeId="removed-diff-9" next="changed-diff-0"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-9" previous="removed-diff-8" changeId="removed-diff-9" next="changed-diff-0"&gt; &lt;/span&gt;&lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-changed" changes="Moved out of a &amp;lt;b&amp;gt;span&amp;lt;/b&amp;gt; with style font-size: 8pt;." previous="removed-diff-9" changeId="changed-diff-0" next="removed-diff-10"&gt; &lt;/span&gt;&lt;span class="diff-html-changed" id="changed-diff-0" changes="Moved out of a &amp;lt;b&amp;gt;span&amp;lt;/b&amp;gt; with style font-size: 8pt;." previous="removed-diff-9" changeId="changed-diff-0" next="removed-diff-10"&gt;NOTE 1 Since a true value cannot be determined, in practice a conventional true value is used&lt;/span&gt;&lt;/div&gt;&lt;div&gt;&lt;span class="diff-html-removed" previous="changed-diff-0" changeId="removed-diff-10" next="removed-diff-11"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-10" previous="changed-diff-0" changeId="removed-diff-10" next="removed-diff-11"&gt; &lt;/span&gt;&lt;/div&gt;&lt;div&gt; NOTE 2 When it is necessary to distinguish “error” from “relative error”, the former is sometimes called absolute error of measurement. This should not be confused with absolute value of error, which is the modulus of the error. &lt;/div&gt;&lt;div&gt;  &lt;/div&gt;&lt;p&gt; &lt;strong&gt;Source&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;  &lt;/p&gt;&lt;div&gt; (1) VIM[&lt;a href="https://www.bipm.org/en/publications/guides/vim.html"&gt;RD18&lt;/a&gt;]&lt;/div&gt;&lt;div&gt; (2) CEOS/ISO:19159 [&lt;a href="https://www.iso.org/obp/ui/#iso:std:iso:ts:19159:-1:ed-1:v1:en"&gt;RD10&lt;/a&gt;]&lt;/div&gt;&lt;div&gt; (3) MACC [&lt;a href="http://www.gmes-atmosphere.eu/documents/maccii/deliverables/man/MACCII_MAN_DEL_D_153.1_20130528_Lambert_V2.pdf"&gt;RD13&lt;/a&gt;]&lt;/div&gt;&lt;div&gt; (4) GUM [&lt;a href="https://www.bipm.org/utils/common/documents/jcgm/JCGM_100_2008_E.pdf"&gt;RD4&lt;/a&gt;]&lt;/div&gt;&lt;p&gt;  &lt;/p&gt;&lt;p&gt; &lt;strong style="font-size: 8pt;"&gt;Suggestions&lt;/strong&gt;&lt;/p&gt;&lt;p&gt; &lt;span style="font-size: 8pt;"&gt;Interestingly the GUM and VIM have slightly different definitions of "error". I find the GUM definition useful.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span class="diff-html-removed" previous="removed-diff-10" changeId="removed-diff-11" next="last-diff"&gt; &lt;/span&gt;&lt;span class="diff-html-removed" id="removed-diff-11" previous="removed-diff-10" changeId="removed-diff-11" next="last-diff"&gt; &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span class="diff-html-removed" previous="removed-diff-10" changeId="removed-diff-11" next="last-diff"&gt; &lt;/span&gt;&lt;strong style="font-size: 8pt;"&gt;&lt;span class="diff-html-removed" previous="removed-diff-10" changeId="removed-diff-11" next="last-diff"&gt;Category&lt;/span&gt;&lt;/strong&gt;&lt;span class="diff-html-removed" previous="removed-diff-10" changeId="removed-diff-11" next="last-diff"&gt;&lt;!----&gt;&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span class="diff-html-removed" previous="removed-diff-10" changeId="removed-diff-11" next="last-diff"&gt; &lt;/span&gt;&lt;a href="https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fcalvalportal.ceos.org%2Ft-d_wiki%3Fp_p_id%3D54_INSTANCE_Wg3ti1194i20%26p_p_lifecycle%3D0%26p_p_state%3Dnormal%26p_p_mode%3Dview%26p_p_col_id%3Dcolumn-2%26p_p_col_count%3D1%26_54_INSTANCE_Wg3ti1194i20_struts_action%3D%252Fwiki_display%252Fview%26_54_INSTANCE_Wg3ti1194i20_nodeName%3DCEOS_Terms_and_Definitions%26_54_INSTANCE_Wg3ti1194i20_title%3D2.%2BMeasurement%2Band%2BMetrology%2Bwords&amp;amp;data=04%7C01%7Cfaye.lai%40npl.co.uk%7C71d207afa14d469389d808d988e92c16%7C601e5460b1bf49c0bd2de76ffc186a8d%7C1%7C0%7C637691357310852893%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;amp;sdata=6Z7RKKAjDIIw%2Bbkm%2ByC1Y59lUo%2FBNQDiM6JtmtGQLes%3D&amp;amp;reserved=0"&gt;&lt;span class="diff-html-removed" previous="removed-diff-10" changeId="removed-diff-11" next="last-diff"&gt;2. Measurement and Metrology words&lt;/span&gt;&lt;/a&gt;&lt;span class="diff-html-removed" previous="removed-diff-10" changeId="removed-diff-11" next="last-diff"&gt;&lt;!----&gt;&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span class="diff-html-removed" previous="removed-diff-10" changeId="removed-diff-11" next="last-diff"&gt;  &lt;/span&gt;&lt;/p&gt;</summary>
    <dc:creator>Paolo Registration Test</dc:creator>
    <dc:date>2020-01-16T11:02:00Z</dc:date>
  </entry>
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