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Personality & Individual Differences, Vol. 7, No. 4, p. 591, 1986
PERILS IN CLINICAL USE OF THE SHOSTROM POI: a reply to Hattie
JOHN J. RAY
Sociology, University of New South Wales, Kensington, Sydney, NSW 2033, Australia
Summary
Hattie confirms the poor reliabilities of the scales in the POI but notes that the POI has a clear factor structure and speculates that the poor scale reliabilities may simply be due to the generality of the concepts covered. It is noted in reply that the clinician would be scoring Shostrom's unreliable scales rather than Hattie's clear factors and it is shown that the poor reliabilities are not due to conceptual generality.
Ray (1984) noted the lack of data on the reliability of the scales in the Shostrom Personal Orientation Inventory (POI) and pointed out that the little data available showed the scales as being vastly less reliable than is usually required in an instrument used for individual diagnosis or even for research into group characteristics.
Hattie (1986, this issue, pp. 593-594) resoundingly makes good the lack of data on the reliability of the POI scales and confirms that the Cronbach alpha coefficients are indeed generally very low. He points out however that he has in his own extensive research with the POI generally found a stable and interpretable factor structure for the inventory as a whole and speculates that the poor alphas may simply be a penalty paid for being so ambitious as to measure quite broad and general concepts.
This speculation is however poorly founded. In the POI scale reported on (Ray, 1984), the low alpha arose not because of a generally low correlation between the items but rather because several of the items correlated with the remaining items in a direction opposite to that keyed. Item 9, for instance, correlated -0.41 with the scale total. It measured, in other words, just the opposite of what Shostrom thought it did. When the nine items correlating < 0.1 with the scale total were removed from consideration, the remaining items showed an alpha of 0.71 -- which is a much more normal figure than the 0.55 initially obtained. Normal item analysis techniques could therefore produce adequate scales from the POI but the scales as keyed by Shostrom could obviously be seriously misleading -- particularly in individual (clinical) use.
Clinicians and researchers who share the formidable factor-analytic skills of Hattie may however be able to make some non-misleading use of the POI. The factor scores may be reliable where the scale scores are not. The two do not appear to have much in common (Hattie, 1981).
REFERENCES
Hattie J. (1981) A four stage factor-analytic approach to studying behavioral domains. Appl. psychol. Measur. 5, 77-88.
Hattie J. (1986) A defence of the Shostrom Personal Orientation Inventory: a rejoinder to Ray. Person. individ. Diff. 7, 593-594.
Ray, J.J. (1984) A caution against use of the Shostrom Personal Orientation inventory. Personality & Individual Differences 5, 755.
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