Validity Evidence in Scale Development: The Application of Cross Validation and Classification-Sequencing Validation

The validity of measuring devices used in education is one of the most important topics of the measuring device development process. Validity concept is a criterion for the fact that it serves as a measuring device (Croker & Algina, 2008; Downing & Haladyna, 2006; Kane, 2006). In other words, identifying the degree of an expected structure and of an observed structure is the structural validity of a test (Baykal, 1994). Thus, the validity of a measurement is directly proportionate to the purpose being measured by the device. Therefore, validity is not a concept to be considered independent of purpose and therefore a set of evidences should be collected. Validity approach according to the purpose of measurement is generally discussed in 3 groups: content, criteria and structural validity (Brualdi, 1999; Erkuş, 2003; Hopkins, 1998). Content validity is related to the fact that the items to be tested represent the structure to be measured. In criterion supported validity, the relationship between points from one test and points from another test are taken as criteria to be examined. Structural validity is the degree to which significant organizational or psychological structures are represented.