A note on reliability estimation for a test with components of unknown functional lengths

This research note proposes two reliability coefficients for tests with components of unknown functional lengths. The derived coefficients are extensions of the techniques devised by Kristof and Feldt and do not require a reduction of test components into parts. Simulation study indicates that the new coefficients yield reasonably stable reliability estimates when the number of test components is small.     

Normative data for eight neuropsychological tests based on a Danish sample

Normative neuropsychological data have been provided using a sample of 101 persons aged 20 to 54 years. Eighty-seven of the subjects were recruited among patients who had undergone minor surgery, and 14 subjects were volunteers from the staff at the hospital laundry. The measures consisted of seven subjects from the WAIS-R, the trail-making test, symbol digit modalities test, auditory-verbal learning test, story recall test, visual gestalt test, recurring figures test, verbal fluency, and Purdue pegboard test. These measures were selected because of suitability in regard to time taken for testing each subject and their sensitivity to subtle changes in neuropsychological functioning. The sample was arbitrarily divided into three age groups, and for each of the three samples, mean, standard deviation, and range were calculated for each test. The results of the Information and Vocabulary subtests from the WAIS-R, education, and social status were applied as independent variables in linear regression analyses where each of the neuropsychological tests, in turn, was the dependent variable. For the oldest age group, age in addition was used as an independent variable. Significant linear relationships, which accounted for an optimal part of the variance, were selected for clinical application.     

An application of order restricted inference methodology to a problem in psychiatry

Using data which reflects upon the genetic makeup of patients, Cadoret, Woolson and Winokur (1977) test two theories regarding the genetic makeup of patients suffering from unipolar affective disorder. This hypothesis test is a good example of a problem in order restricted inference. Using some recently developed techniques in order restricted inference we analyze these data and compare the analyses.This research was sponsored by the Office of Naval Research under contract N00014-80-C-0321.     

Rasch's model for reading speed with manifest explanatory variables

In educational and psychological measurement we find the distinction between speed and power tests. Although most tests are partially speeded, the speed element is usually neglected. Here we consider a latent trait model developed by Rasch for the response time on a (set of) pure speed test(s), which is based on the assumption that the test response times are approximately gamma distributed, with known shape parameters and scale parameters depending on subject ability and test difficulty parameters. In our approach the subject parameters are treated as random variables having a common gamma distribution. From this, maximum marginal likelihood estimators are derived for the test difficulties and the parameters of the latent subject distribution. This basic model can be extended in a number of ways. Explanatory variables for the latent subject parameters and for the test parameters can be incorporated in the model. Our methods are illustrated by the analysis of a simulated and an empirical data set.     

Repeated challenge studies: A comparison of union-intersection testing with linear modeling

Challenge studies are often implemented for assessing whether a subject is sensitive to a certain agent or allergen. In particular, researchers test groups of subjects to determine if there really exists a causal relationship between some agent of interest and a response. To answer such a question, we need to detect the presence of the phenomenon in just one individual. Typically, however, there are a large number of unknown risk factors associated with the response and a potentially small population prevalence. Hence, standard statistical techniques, by averaging the treatment effect across the group, may miss a significant response of a single individual and lead to inconclusive results. We develop an alternative approach based on union-intersection testing that will allow a practitioner to correctly examine observations on an individual apart from the other subjects and test the hypothesis of interest: Does the phenomenon exist in the population? More specifically, we show how this technique adjusts for the multiple number of tests encountered when analyzing data for each individual subject separately. Furthermore, we demonstrate power calculations for the determination of sample size prior to performing the study. The performance of the union-intersection approach in comparison to linear models and semiparametric techniques is considered through sample size calculations and simulations. The union-intersection testing methodology out performs the Kolmogorov tests. However, the nested linear model performs as well if not better than the union-intersection tests. To illustrate the ideas presented in the paper, we provide an application in which we analyze psychological data collected by way of a challenge study design.     

Nonunique solutions to the likelihood equation for the three-parameter logistic model

Samejima identified the possibility of multiple solutions to the likelihood equation (multiple maxima in the likelihood function) for estimating an examinee's trait value for the three-parameter logistic model. In the practical applications that Lord studied, he found that multiple solutions did not occur when the number of items was 20. In the present paper, fourteen multiple-choice achievement tests with from 20 to 50 items were examined to see if it was possible for them to produce item response vectors with multiple maxima; such vectors were found for all the tests. Examination of response vectors for large groups of real examinees found that from 0 to 3.1% of them had response vectors with multiple maxima. The implications of these results for multiple-choice tests are discussed.     

States of identity: a perspective drawing upon Fordham's model and infant studies

This paper examines the Jungian concept of identity and distinguishes it from projective identification and participation mystique which also refer to non-differentiation between self and object but involve projective mechanisms. Clinical work by Fordham and a psychoanalytic infant observation are used to illustrate early perceptual operations defined by experimental researches. These operations are understood to be expressions of the primary self which manifest themselves before the structuring necessary for normal projective identification. This paper attempts to describe an intersubjective experience between mother and baby that allows for their separate ways of relating, but does not depend on projective mechanisms that can exist only after there has been adequate development.