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Reliability and Validility

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Reliability and Validility

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  • October 2011
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Reliability and Validity
Ebony Johnson
University of Phoenix

Reliability has to do with the quality of measurement and is the consistency of repeatability of measures. To define it precisely researchers first have to learn about the foundation of reliability- the true score theory of measurement. Then researchers need to understand the different types of measurement error because they play a key role in degrading reliability. Because reliability can only be estimated there are different types of reliability that has multiple ways to estimate reliability for that type. In the end it is important to integrate the idea of reliability with the other major criteria for the quality of measurement, validity. Validity refers to the degree to which a study accurately reflects or assesses the specific concept the researcher is attempting to measure. Validity is concerned with the study's success at measuring what the researchers set out to measure. Reliability is defined as a criterion used to define the consistency, stability, and dependability of how all the information is suited for the purpose intended. For example, when researchers look at human services and human service management reliability can be used to measure the behaviors associated with parenting skills, job performance or mental health status. There are five types of reliability alternate form reliability is the degree of relatedness of different forms of the same test. Then there is internal-consistency reliability, which is the degree of relatedness of items in a test or all raters in a judgment study. Judge-to-judge reliability is the reliability of any single item on average. Finally, test-retest reliability which is the degree of temporal stability of a measuring instrument or test, or the characteristic it is designed to evaluate from one administration to another.

Validity is a measure used to show how well the measure or design does what it states that it is going to do. For example,...