TECHNICAL PERFORMANCE of the Singer-LoomisType Deployment Inventory
Scientifically proven reliability and validity
In addition to the in-house Moving Boundaries research database used by Moving Boundaries to understand the statistical performance of the SL-TDI, a comprehensive independent study of the validity and reliability of the SL-TDI was conducted recently. The Cronbach alpha scores in this study are virtually identical to those generated by a Moving Boundaries analysis of sample of 1534 cases. The Arnau, et. al. research, which is summarized below, carefully tested the reliability and validity of the SL-TDI and found that in all of the ways it was tested, the SL-TDI performed at a psychometrically acceptable level. The material that follows is a summary of the article.
SUMMARY: Arnau, R.C., Rosen, H.R. & Thompson, B. (2000). Reliability and validity of scores from the Singer-Loomis Type Deployment Inventory. Journal of Analytical Psychology, 45, 409-426.
Purpose of Study. Given that Jung’s theory of personality is a highly accepted approach in mainstream counseling and psychology, the authors noted that the MBTI, the most popular measurement instrument of Jungian typology, had been seriously criticized in the literature for its dependence on a forced-choice format that results in spurious negative correlation’s among items. This format is based on an assumption of bipolar functioning of the personality. In reviewing Jung’s theory (1971) they found that he stated that bipolarity occurs only in a well-differentiated personality. Jung also postulated that development continues across the lifespan. Therefore, a system of measurement of psychological types should allow for varying levels of development of functions and attitudes rather than classifying a person as a type. The Singer-Loomis Type Deployment Inventory (SL-TDI) has been constructed with these issues in mind.
The authors then sought to evaluate the following psychometric properties of the SL-TDI scores by: (1) providing additional estimates of internal consistency of SL-TDI scores than have been provided by previous studies, (2) evaluating divergent validity of the SL-TDI scores by examining relationships with social desirability scores and (3) examining test-retest stability of SL-TDI scores.
Methods. The participants for their study consisted of 165 college students (57 males and 108 females). Each student completed a demographic questionnaire, the SL-TDI and the Marlowe-Crown Social Desirability Scale. Two weeks later, the students were again administered the SL-TDI.
Results. The authors then calculated internal consistency scores for each SL-TDI scale (IS, ES, IN, EN, IT, ET, IF and EF) using Cronbach’s alpha. Scores ranged from .65 (acceptable) to .91 (excellent). As predicted, SL-TDI scores did not correlate with Marlowe-Crowne scores, indicating that social desirability was not a factor influencing responses. Test-retest results for raw scores showed acceptable stability over the two-week period, as they had been in Arnau’s earlier study.
Discussion. This study replicated prior studies indicating reliability and validity of the SL-TDI as indicated by internal consistency, divergent validity and test-retest reliability. Given its situational format using a Likert scale of measurement for each item, the SL-TDI was found to be free of the psychometric criticisms directed at the MBTI. In addition, the authors found that the SL-TDI more closely represented Jung’s theory of personality since it does not assume a bipolar relationship among the functions and scales and can measure an individual’s personality at any level of development. One finding was the difference in stability between raw scores and the ipsative percentage scores. The ipsatised percentage scores were less stable. This indicated that when conducting research or in clinical settings, raw scores should be used.