Imagine that for each person you are measuring, you are taking a shot at the target. If you measure the concept perfectly for a person, you are hitting the center of the target.
If you don't, you are missing the center. The more you are off for that person, the further you are from the center. The figure above shows four possible situations. In the first one, you are hitting the target consistently, but you are missing the center of the target.
That is, you are consistently and systematically measuring the wrong value for all respondents. This measure is reliable, but no valid that is, it's consistent but wrong. The second, shows hits that are randomly spread across the target. You seldom hit the center of the target but, on average, you are getting the right answer for the group but not very well for individuals.
In this case, you get a valid group estimate, but you are inconsistent. Here, you can clearly see that reliability is directly related to the variability of your measure. The third scenario shows a case where your hits are spread across the target and you are consistently missing the center. Your measure in this case is neither reliable nor valid. No problem, save it as a course and come back to it later. Martyn Shuttleworth K reads. Share this page on your website: This article is a part of the guide: Select from one of the other courses available: Don't miss these related articles:.
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Define reliability, including the different types and how they are assessed. Define validity, including the different types and how they are assessed. Describe the kinds of evidence that would be relevant to assessing the reliability and validity of a particular measure.
Types of Reliability. Test-retest reliability is a measure of reliability obtained by administering the same test twice over a period of time to a group of individuals. The scores from Time 1 and Time 2 can then be correlated in order to evaluate the test for stability over time.
Reliability is a necessary ingredient for determining the overall validity of a scientific experiment and enhancing the strength of the results. Debate between social and pure scientists, concerning reliability, is robust and ongoing. Issues of research reliability and validity need to be addressed in methodology chapter in a concise manner. Reliability refers to the extent to which the same answers can be obtained using the same instruments more than one time. In simple terms, if your research is associated with high levels of.
When we look at reliability and validity in this way, we see that, rather than being distinct, they actually form a continuum. On one end is the situation where the concepts and methods of measurement are the same (reliability) and on the other is the situation where concepts and methods of measurement are different (very discriminant validity). Face Validity is the most basic type of validity and it is associated with a highest level of subjectivity because it is not based on any scientific approach. In other words, in this case a test may be specified as valid by a researcher because it may seem as valid, without an in-depth scientific justification.