Minimizing the number of observations: A generalization of the spearman-brown formula

A new method for determining the minimum number of observations per subject needed to achieve a specific generalizability coefficient is presented. This method, which consists of a branch-and-bound algorithm, allows for the employment of constraints specified by the investigator.     

Ordinal consistency and ordinal true scores

This paper argues that test data are ordinal, that latent trait scores are only determined ordinally, and that test data are used largely for ordinal purposes. Therefore it is desirable to develop a test theory based only on ordinal assumptions. A set of ordinal assumptions is presented, including an ordinal version of local independence. From these assumptions it is first shown that the gamma-correlation between two tests is the product of their gamma-correlations with the true latent order. The theory is generalized to allow for heterogeneous tests by defining a weighted average local independence. The tau-correlations between total score and the latent order can be found in both homogeneous and heterogeneous cases, and a system of differential item weighting to maximize the tau-correlation between weighted items and the latent order is provided. Thus a purely ordinal test theory seems possible.Part of this work was done while the author was a Visiting Fellow at Macquarrie University. The paper has benefitted from discussions with Professors Thomas J. Reynolds and Roderick P. McDonald and from the comments of several anonymous reviewers.     

Reliability of test scores in nonparametric item response theory

Three methods for estimating reliability are studied within the context of nonparametric item response theory. Two were proposed originally by Mokken (1971) and a third is developed in this paper. Using a Monte Carlo strategy, these three estimation methods are compared with four classical lower bounds to reliability. Finally, recommendations are given concerning the use of these estimation methods.The authors are grateful for constructive comments from the reviewers and from Charles Lewis.     

A family of chance-corrected association coefficients for metric scales

A chance-corrected version of the family of association coefficients for metric scales proposed by Zegers and ten Berge is presented. It is shown that a matrix with chance-corrected coefficients between a number of variables is Gramian. The members of the chance-corrected family are shown to be partially ordered. The author is obliged to Jos ten Berge for helpful comments.     

Reactivity and unreliability of husbands as participant observers

This study examined the reliability and reactivity of participant observation. Twelve couples engaged in two discussions in a laboratory, one on a conflict topic and one on a consensus topic. For the eight couples in the experimental sequences, a baseline discussion was followed by participant observation in which the husband recorded his wife's use of I while continuing to converse. The four couples in the control sequences conversed without participant observation. Compared to observations made by a trained observer, the husbands were unreliable observers, underestimating their wives' use of I. Participant observation was reactive (P<.01), with more wives decreasing their use of I in the experimental sequences than in the control sequences (p<.094). The topic of discussion did not differentially influence reliability or reactivity.This research was conducted as the first author's independent doctoral research project. We extend gratitude to the Research Council of the University of North Carolina at Greensboro for Grant 0-2-110-218-XXXXX-7548; the Statistical Consulting Center of the University of North Carolina at Greensboro; two anonymous reviewers; and our research assistants, Suzanne Brannon, Ben Hardie, Kathy Lindamood, Amy Mitchem, Regina Pierce, and Elga Wulfert. Portions of this paper were presented at the meeting of the Association for Advancement of Behavior Therapy, Washington, D.C., December 1983.     

Internal consistency and reliability of alternate short forms of the college women's assertion sample: Clinical and research implications

Assertive behavior is most often assessed with self-report or role-play measures. The latter modality is preferred because it provides for the sampling of the structure of behavior and for the consideration of the situational context. MacDonald (1978) has developed such an assessment device but it is limited by the length of time for administration and scoring. Two studies were conducted to reconstruct reliable alternate short forms. The first study describes the selection of items and demonstrates the internal consistency of the alternate forms. The second study demonstrates the alternate form and retest reliability and provides normative statistics. We conclude that reliable alternate short forms have been constructed to be used in research in clinical applications.This research was supported by the Marie Wilson Howells Fund.Alternate short forms of the CWAS may be obtained from the first author.     

Some relationships between the information function of IRT and the signal/noise ratio and reliability coefficient of classical test theory

It is shown that IRTs information function for an item is functionally related to local versions of classical test theories' signal/noise ratio and reliability coefficient.     

A generalized family of coefficients of relational agreement for numerical scales

A family of coefficients of relational agreement for numerical scales is proposed. The theory is a generalization to multiple judges of the Zegers and ten Berge theory of association coefficients for two variables and is based on the premise that the choice of a coefficient depends on the scale type of the variables, defined by the class of admissible transformations. Coefficients of relational agreement that denote agreement with respect to empirically meaningful relationships are derived for absolute, ratio, interval, and additive scales. The proposed theory is compared to intraclass correlation, and it is shown that the coefficient of additivity is identical to one measure of intraclass correlation.The author thanks the Editor and anonymous reviewers for helpful suggestions.     

Swedish translations of the Suicide Probability Scale, Perceived Social Support from Friends and Family Scales, and the Scale for Interpersonal Behavior: A reliability analysis

The Suicide Probability Scale (SPS), the Perceived Social Support (PSS) from Friends (PSS-Fr) and Family (PSS-Fa) scales, and the Scale for Interpersonal Behavior (SIB) were translated into Swedish and their reliability was estimated in a university student sample. The reliability coefficients indicated that both subscales and the total scales of the SPS, PSS, and SIB possess highly adequate reliabilities. The intercorrelations among the subscales and between the subscales and the total scales were found to be highly significant. The results of the study supported the use of SPS, PSS-Fr and PSS-Fa, and the SIB as reliable methods for assessing suicide risk, perceived social support from friends and family, and assertive behavior.