Equivalence of the Paper-Pencil and Web-Based Versions
Since the web-based CK uses the same test items and occupational classification system, it was expected that its reliability, validity, and helpfulness would be comparable to that found with the paper-pencil version of the CK. Jones and Ward (2002) confirmed this in a recent study of 265 high school students. The results showed that they were comparable with respect to their reliability, validity, and helpfulness as reported by students.
Levinson, Zeman and Ohler (2002) investigated the reliability and validity the web-based version of the CK among college students. Ninety-nine undergraduates completed the Web-based version of the CK and the Self-Directed Search (SDS) -- Form R (J. L. Holland, 1994) in counterbalanced order and completed a second CK administration two weeks after completing the first test administration. Test-retest reliability ranged between .75 and .84 for the six scales. With the exception of the Conventional scale (.47), all concurrent validity coefficients were at or above .65.
To explore the concurrent validity of the CK, they compared the three-letter code for each participant with the three-letter code they received from the SDS. They conducted two different types of analyses. In the first analysis, the CK and SDS had the same letter in the first position 72% of the cases, the same letter in the second position in 37% of the cases, and the same letter in the third position 41% of the cases. In the second analysis, the CK and SDS had the same letter in the first position 94% of the cases, 85% of the cases for the second position, and 76% of the cases for the third position.
They concluded, "The results of this study are encouraging, and they generally support the reliability and validity of the CK (p. 31)."