Reliability and Validity are important aspects of research in the human services field. Without reliability and validity researchers results would be useless. This paper will define the types of reliability and validity and give examples of each. Examples of a data collection method and data collection instruments used in human services and managerial research will be given. This paper will look into why it is important to ensure that these data collection methods and instruments are both reliable and valid.
Reliability
Many types of reliability are used in research. Alternate-form reliability is the degree of relatedness of different forms of the same test. An example of alternate form reliability is a psychological test where the questions are changed. Internal-consistency reliability is the overall degree of relatedness of all items in a test or all raters in a judgment study. Internal-consistency is measured between different items on the same test. For example, if a respondent expressed agreement with the statements "I like to ride roller coasters" and "I've enjoyed riding roller coasters in the past", and disagreement with the statement "I hate riding roller coasters", this would be indicative of good internal consistency of the test. Item-to-item reliability is the reliability of any single item on average. An example would be the reliability of two items such as a collectors coins that are identical. Test-retest reliability is the degree of temporal stability (relatedness) of a measuring instrument or test, or the characteristic it is designed to evaluate, from one administration to another. (Rosnow, 2008) Statitcs.com (n.d) states, “a group of respondents is tested for IQ scores: each respondent is tested twice - the two tests are, say, a month apart. Then, the correlation coefficient between two sets of IQ-scores is a reasonable measure of the test-retest reliability of this test.” (Para. 2) It is more reliable