{"id":8250,"date":"2019-05-22T16:05:40","date_gmt":"2019-05-22T16:05:40","guid":{"rendered":"http:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/internal_consistency\/"},"modified":"2019-05-22T16:05:40","modified_gmt":"2019-05-22T16:05:40","slug":"internal_consistency","status":"publish","type":"post","link":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/internal_consistency\/","title":{"rendered":"Internal consistency"},"content":{"rendered":"<p>Internal consistency refers to an important requirement for composite scales, in which the individual items or tests making up the scale are statistically associated with each other. &nbsp;If so, then it can be assumed that they are all measuring the same construct or attribute. &nbsp;It is important to note that measures of internal consistency do not constitute tests of the unidimensionality of items in a scale. &nbsp;For example, if the first half of a scale consists of cognitive items (correlating highly among themselves), and the second half items concerning achievement motivation (also correlating highly among themselves), the scale would have a high internal consistency value, despite the fact that there were two distinct dimensions. &nbsp;Moreover, referring to internal consistency as &#8216;internal consistency reliabilit&#8217;, as is often done, can be a source of confusion as this conflates two distinct concepts (viz., internal consistency and reliability), which do not necessarily go together. There are a variety of estimates of internal consistency, the most widely used being Cronbach&#8217;s alpha (others being, for example, the <a href=\"http:\/\/psych.colorado.edu\/~carey\/Courses\/PSYC5112\/Readings\/alpha_Cronbach.pdf\" class=\"cc-route-enabled\" target=\"_self\" data-editable-link=\"http:\/\/psych.colorado.edu\/~carey\/Courses\/PSYC5112\/Readings\/alpha_Cronbach.pdf&amp;target=_self\" rel=\"noopener noreferrer\">Kuder-Richardson formulas<\/a> and the <a href=\"http:\/\/www.jalt.org\/test\/PDF\/Brown9.pdf\" target=\"_self\" data-editable-link=\"http:\/\/www.jalt.org\/test\/PDF\/Brown9.pdf&amp;target=_self\" rel=\"noopener noreferrer\">Spearman-Brown prophecy formula)<\/a>.&nbsp;<\/p>\n<p>See <a href=\"composite_-or_sum-_scale\">Composite (or sum) scale<\/a>, <a href=\"construct\">Construct<\/a>, <a href=\"cronbach-s_alpha\">Cronbach&#8217;s alpha<\/a>, <a href=\"multitrait-multimethod_matrix\">Multitrait-multimethod matrix<\/a>, <a href=\"reliability\">Reliability<\/a><\/p>\n<p><\/p>\n<p><\/p>\n<p><\/body><\/html><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Internal consistency refers to an important requirement for composite scales, in which the individual items or tests making up the scale are statistically associated with each other. &nbsp;If so, then it can be assumed that they are all measuring the same construct or attribute. &nbsp;It is important to note that measures of internal consistency do &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/internal_consistency\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Internal consistency&#8221;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[2],"class_list":["post-8250","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-glossary","entry"],"_links":{"self":[{"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/posts\/8250","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/comments?post=8250"}],"version-history":[{"count":0,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/posts\/8250\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/media?parent=8250"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/categories?post=8250"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lancaster.ac.uk\/fas\/psych\/glossary\/wp-json\/wp\/v2\/tags?post=8250"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}