{"id":83672,"date":"2019-08-08T12:54:48","date_gmt":"2019-08-08T10:54:48","guid":{"rendered":"https:\/\/www.scribbr.nl\/?p=83672"},"modified":"2023-06-22T13:30:06","modified_gmt":"2023-06-22T11:30:06","slug":"types-of-reliability","status":"publish","type":"post","link":"https:\/\/www.scribbr.com\/methodology\/types-of-reliability\/","title":{"rendered":"The 4 Types of Reliability in Research | Definitions & Examples"},"content":{"rendered":"

Reliability<\/strong> tells you how consistently a method measures something. When you apply the same method to the same sample<\/a> under the same conditions, you should get the same results. If not, the method of measurement may be unreliable or bias<\/a> may have crept into your research.<\/p>\n

There are four main types of reliability. Each can be estimated by comparing different sets of results produced by the same method.<\/p>\n\n\n\n\n\n\n\n<\/tr>\n\n<\/tr>\n<\/tbody>\n<\/table>\n

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Test-retest reliability<\/h2>\n

Test-retest reliability measures the consistency of results when you repeat the same test on the same sample at a different point in time. You use it when you are measuring something that you expect to stay constant in your sample.<\/p>\n

A test of color blindness for trainee pilot applicants should have high test-retest reliability, because color blindness is a trait that does not change over time.<\/div>\n

Why it’s important<\/h3>\n

Many factors can influence your results at different points in time: for example, respondents might experience different moods, or external conditions might affect their ability to respond accurately.<\/p>\n

Test-retest reliability can be used to assess how well a method resists these factors over time. The smaller the difference between the two sets of results, the higher the test-retest reliability.<\/p>\n

How to measure it<\/h3>\n

To measure test-retest reliability, you conduct the same test on the same group of people at two different points in time. Then you calculate the correlation<\/a> between the two sets of results.<\/p>\n

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Test-retest reliability example<\/h6>\n

You devise a questionnaire to measure the IQ of a group of participants (a property that is unlikely to change significantly over time).You administer the test two months apart to the same group of people, but the results are significantly different, so the test-retest reliability of the IQ questionnaire is low.<\/p>\n<\/div>\n

Improving test-retest reliability<\/h3>\n

Type of reliability<\/th>\nMeasures the consistency of…<\/th>\n<\/tr>\n<\/thead>\n
Test-retest<\/a><\/th>\nThe same test over time<\/strong>.<\/td>\n<\/tr>\n
Interrater<\/a><\/th>\nThe same test conducted by different people<\/strong>.<\/td>\n<\/tr>\n
Parallel forms<\/a><\/th>\nDifferent versions<\/strong> of a test which are designed to be equivalent.<\/td>\n<\/tr>\n
Internal consistency<\/a><\/th>\nThe individual items<\/strong> of a test.<\/td>\n<\/tr>\n
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If possible and relevant, you should statistically calculate reliability and state this alongside your results<\/a>.<\/p>\n

Other interesting articles<\/h2>\n

If you want to know more about statistics<\/a>, methodology<\/a>, or research bias<\/a>, make sure to check out some of our other articles with explanations and examples.<\/p>\n

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<\/em>Statistics<\/strong><\/p>\n

What is my methodology?<\/th>\nWhich form of reliability is relevant?<\/th>\n<\/tr>\n<\/thead>\n
Measuring a property that you expect to stay the same over time.<\/td>\nTest-retest<\/td>\n<\/tr>\n
Multiple researchers making observations or ratings about the same topic.<\/td>\nInterrater<\/td>\n<\/tr>\n
Using two different tests to measure the same thing.<\/td>\nParallel forms<\/td>\n<\/tr>\n
Using a multi-item test where all the items are intended to measure the same variable.<\/td>\nInternal consistency<\/td>\n<\/tr>\n