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Scale Properties of the Interest Index

Halpern, Gerald
Publication Year:
Report Number:
RB-65-40, RDR-65-66 No. 05
ETS Research Bulletin
Document Type:
Page Count:
Subject/Key Words:
Construct Validity, Interest Index, Interest Inventories, Student Interests, Test Reliability


Extensive research by John French on the Interest Index produced a 12-scale interest test with 16 items per scale. The present study investigated certain scale properties of the Interest Index. Internal consistency coefficients were found to cluster about .91, item-scale assignment was verified for 99% of the items, scale test-retest correlations (three-week interval) were found to cluster about .86, and the individual scales were found to be remarkably independent of one another. It was concluded that, on all these measures, the Interest Index performs at least as well as any comparable test and, in addition, has three advantages over most. It is a very efficient instrument (in terms of number of items per scale), it utilizes subject matter experiences familiar to most students, and it measures interest in a wide variety of subject matter course areas. Partial confirmation of the construct validity of this test is provided, and it is recommended that (a) appropriate norms be developed and (b) further validation studies be conducted.

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