Gregorc's study Timothy Sewall, in a comparison of four learning style assessments (Gregorc's, Myers Briggs, Kolb LSI, and an LSI by Canfield) by review of their published supporting studies (i.e., without new experimental work) concluded of Gregorc's design, "the most appropriate use of this instrument would be to provide an example of how not to construct [an] assessment tool." Studies by others Reio and Wiswell (2006) report on their own independent study and on those done earlier by O'Brien (1990) and Joniak and Isakson (1988). Reliability Internal consistency or reliability concerns whether evidence can show that an instrument is repeatably measuring something (which may be, but is "not necessarily what it is supposed to be measuring"). Gregorc (1982c) reported test-retest correlation coefficients of .85 to .88 (measured twice with intervals ranging from 6 hours to 8 weeks) and alpha coefficients of .89 to .93 on all four scales. In this study, the Cronbach's alpha coefficients on all scales or channels ranged from .54 to .68 (CS = .64, CR = .68, AR = .58, AS = .54). This study's alpha coefficients are consistent with those reported by O'Brien (1990) and Joniak and Isakson (1988), which ranged from .51 to .64 and .23 to .66, respectively, on all scales. For internal consistency reliability estimates, although an alpha level of .70 can be considered "adequate," for the purposes of this study we considered a stricter alpha level of .80 as a "good" cutoff value for our psychometric examination of the GSD (Henson, 2001). Construct validity Construct validity concerns whether evidence can show that what the instrument is measuring is at all what the offered theory claims it is (whether each construct in the model "adequately represents what is intended by theoretical account of the construct being measured"). The data disconfirmed both the two- and four-factor confirmatory models. In the post hoc exploratory factor analyses, many of the factor pattern/structure coefficients were ambiguously associated with two or more of the four theoretical channels as well. Overall, there was little support for the GSD's theoretical basis or design and the concomitant accurate portrayal of one's cognitive learning style. [F]ar more work is needed on the GSD if indeed two bipolar dimensions and Gregorc's mediational or channel theory are to be empirically supported and if it is to be appropriately used with samples of adults. Consistent with Joniak and Isaksen (1988) and O'Brien (1990), the