Summed-score linking using item response theory: application to depression measurement.

An item response theory (IRT) approach to test linking based on summed scores is presented and demonstrated by calibrating a modified 23-item version of the Center for Epidemiologic Studies Depression Scale (CES-D) to the standard 20-item CES-D. Data are from the Depression Patient Outcomes Research Team, II, which used a modified CES-D to measure risk for depression. Responses (N = 1,120) to items on both the original and modified versions were calibrated simultaneously using F. Samejima's (1969, 1997) graded IRT model. The 2 scales were linked on the basis of derived summed-score-to-IRT-score translation tables. The established cut score of 16 on the standard CES-D corresponded most closely to a summed score of 20 on the modified version. The IRT summed-score approach to test linking is a straightforward, valid, and practical method that can be applied in a variety of situations.

Sexual attitudes and behavior of bulimic women: A preliminary investigation.

One-hundred and seventeen college-aged women at varying risk for developing bulimia answered a number of questions addressing their attitudes toward and comfort with sexuality as well as their sexual and contraceptive history. Risk for developing bulimia was unrelated to sexual attitudes and weakly related to greater comfort with sexuality. High-risk women reported first engaging in intercourse at earlier ages and were also more likely to engage in risky contraceptive behavior than their lower risk counterparts. Despite their tendency to report a greater number of previous sexual partners, high-risk women currently engaged and expected to continue to engage in sex less frequently than lower risk women. Taken together with previous findings, results suggest that the relationship between risk for bulimia and certain patterns of sexual behavior reflects a general cycle of impulsive and controlling behavior exhibited by high-risk women. Limitations and implications of the present study are discussed.

Parent-specific adjustments for evaluation of recumbent length and stature of children.

A clinical "parent-specific" method for evaluating recumbent length and stature of children, allowing for the stature of parents, is presented. This method uses midparent stature and allows adjustment of recumbent length (birth to 3 years) and stature (3 to 18 years) of US children relative to National Center for Health Statistics growth charts. The method is based on parent-child relationships for 586 midparent-child pairs participating in the Fels Longitudinal Study, and on more than 16,000 serial measurements of recumbent length and stature. The method provides a clinical tool to separate the normal genetic contribution of parental stature to stature of children from other factors that affect stature such as malnutrition or disease.

Determinants of cognitive abilities in the elderly.

One hundred and fifteen men between the ages of fifty and ninety-three were administered six cognitive tasks: a verbal intelligence subtest, a nonverbal intelligence subtest, two tests of concrete operations, one test of formal operations, and a problem-solving task. The obtained scores were factor analyzed. Two factors were obtained, a nonverbal, performance factor and a verbal-reasoning factor. Regression analyses in which age, education, occupation, years since retirement, health status, activity level, and marital status were predictor variables performed on the factor scores obtained for each of the factors. The nonverbal performance factor was significantly predicted by age while the verbal factor was significantly predicted by education. None of the other predictors were significant. The results suggest that verbal and nonverbal abilities may be determined by different antecedents. Since different cognitive abilities may have different antecedents and since these antecedents may have different relationships to age, it is important to view adult cognitive development as multidimensional and multidirectional rather than as normative and unidirectional.

Measurement of growth in children with renal insufficiency.

The serial measurement of stature, weight, skin-fold thickness, mean arm circumference, skeletal maturity, and where appropriate, stage of sexual development are recommended as suitable indices for assessing growth in children with kidney disease. Methods of expressing the data for evaluating the individual child are generally used methods. Emphasis is given to relating stature to bone age in evaluating growth potential. Methods for comparing growth rates in groups of children are less well-developed. Using standard deviation scores is recommended for comparing stature in two groups of children or in the same child observed at the end of two different regimens. Weight using ideal weight-for-height as reference from a group of children can be treated statistically. Data of skinfold thickness and arm circumference from two groups can be handled statistically only when the groups are comparable in age and sex.

Individual growth in stature: a comparison of four growth studies in the U.S.A.

Patterns of growth in stature of subjects from the four major U.S. longitudinal growth studies are compared by means of a two-component model for individual growth. Problems inherent in the comparison of data from independent growth studies, such as those arising from different methods of sampling subjects and scheduling measurements and the occurrence of atypical subjects, are considered and solutions are offered. Statistical tests of the individual growth parameters revealed significant, but small, differences among the samples in the magnitude of the contributions of prepubertal and adolescent growth to mature stature and in the velocity of growth. No differences between samples in the timing of the adolescent component were detected.

Two programs for predicting adult stature for individuals.

Two computer programs are described which use the new RWT method to predict adult stature for individuals. This method, developed and described by Roche et al. is the best and most accurate one available to date. The two programs are prepared with different aims in different languages. Program 1 is interactive, written in BASIC and is aimed for the clinician who needs predictions for just a few individuals at a time. Program 2 is written in FORTRAN and is meant for large-scale batch processing. It is thought that this mode is better for the researcher who is more interested in large-scale testing of hypotheses about such things as the efficacy of intervention programs in human growth.

Hereditary and environmental determinants of growth in height in a longitudinal sample of children and youth of Guatemalan and European ancestry.

The effects of hereditary and environmental factors upon the growth in stature of children living in Guatemala City has been studied. Heights at yearly examinations were fitted, by individual, to a double logistic curve in samples of Guatemalan and European children attending a private school in Guatemala City. These two samples differed genetically yet shared the same environment. Their growth was compared, by a multivariate analysis of the parameterized curves, to that of children from the Berkeley Growth Study, genetically similar to the European sample, yet living in different environments. The European children in Guatemala grew, before adolescence, more similar to Guatemalan and differed significantly from the Berkeley sample children. However, the amount of growth during the adolescent years experienced by the European children was similar to that of the Berkeley sample and differed from their Guatemalan counterparts.

The RWT method for the prediction of adult stature.

The Roche- Wainer- Thissen (RWT) method estimates the adult stature of an individual from data recorded at a single childhood examination. The data required are recumbent length, nude weight, midparent stature, and hand-wrist skeletal age. If necessary, a measurement of the child's stature can be transformed to be approximately equivalent to recumbent length with little loss of accuracy. When applied to data from three longitudinal growth studies, the prediction errors with the RWT method were smaller than those with the method of Bayley and Pinneau.

A double logistic comparison of growth patterns of normal children and children with Down's syndrome.

A double logistic model was used to compare six parameters of growth in standing height of 31 children with Down's syndrome with 136 children from the California Guidance Study. Multivariate analysis of variance of the growth data showed that while there were significant differences in all six parameters favouring the normal over the Down's children, there were no significant differences with respect to error of fit. Multivariate analysis with final height as a covariate revealed that differences between the normal and the Down's children in the prepubertal and adolescent components were explainable by differences in final height. In summary, the double logistic model, when applied to this sample of Down's children, identified those well defined logistic components which are characteristic of the growth of normal children, the differences being those of degree, not of form.