Overlap In Variance Research Articles

Using Short-Term Concentration Measures and Intelligence in Rehabilitation Settings

Psychological assessment of cognitive functioning among clinical groups that include psychiatric and geriatric patients is a difficult task. This study examines the interrelationship between intelligence and concentrative ability for a group of psychiatric patients. Intellectual and concentrative ability were assessed among a group of 85, predominantly schizophrenic, patients (mean age 32 years) from a Sheltered Workshop (GWN) and neurological-psychiatric institutionalized care units within the Neuss region of North-Rhine Westphalia, Germany. Moderate bivariate relationships were found between all IQ subtests and the concentration performance variables (d2). A substantial overlap in variance was found between “nonverbal” intelligence and the concentration variables (using multiple regression and discrimination analysis). Error rate on the concentration task was significantly negatively correlated with the IQ variables, the magnitude of the correlation coefficient increasing as a function of the time on the task. Future studies would benefit from comparisons in factor structure similarity between abnormal and normal groups as well as between-clinical groups. At a practical level, the relatively easy use (less complex administration) and less obtrusive (hence, low level of personal threat) and inexpensive procedures of the letter cancellation task makes it a useful, albeit “approximate”, measure of cognitive functioning.

MMPI-2 Content Scale Validity Within a Sample of Chronic Pain Patients

The concurrent, criterion-related and discriminant validity of four of the MMPI-2 content scales were examined within a population of 309 patients being evaluated for the treatment of chronic pain. Utilizing both self-report and therapist-derived criteria, the MMPI-2 content scales designed to assess symptoms of anxiety (ANX), depression (DEP), low self-esteem (LSE), and anger (ANG) demonstrated the ability to provide valid information beyond that provided by the traditional MMPI-2 clinical and validity indices. Further, a multi-trait/multi-method analytic approach revealed; (1) strong discriminant validity for the ANG content scale and (2) substantial variance overlap among all the self-report measures of subjective distress, compromising our efforts to evaluate the discriminant validity of the ANX, DEP, and LSE content scales.

Exploration of the Underlying Dimensions and Overlap between the Kaufman Adolescent and Adult Intelligence Test and the Wechsler Memory Scale-Revised

The canonical relationship between the Kaufman Adolescent and Adult Intelligence Test (KAIT) and the Wechsler Memory Scale-Revised (WMS-R) was studied. Two significant canonical variates accounted for approximately 53% of the overlap in variance between the two measures. The WMS-R was found to offer unique and valuable information beyond the KAIT when assessing individuals classified as learning disabled (LD). Principal components analysis, using the KAIT Composite IQs and the WMS-R Index scores, yielded a two-factor solution. The addition of a specific measure of memory during the psychoeducational evaluation of adolescents and adults classified as LD was supported. Implications for clinical practice and recommendations for future research are discussed.

A comparison of period amplitude and power spectral analysis of sleep EEG in normal adults and depressed outpatients

Three experiments were carried out to evaluate the relationship between two techniques for quantifying electroencephalographic (EEG) data during sleep: period amplitude analysis (PAA) and power spectral analysis (PSA). In Experiment 1, canonical correlations and regression analyses were computed on PSA and PAA data from 40 undergraduate volunteers. The results yielded an average canonical correlation of 0.98. Further, multiple regression analyses demonstrated that the PSA variables accounted for approximately 66% of the variance in the PAA data, whereas PAA variables captured 88% of the variance in the PSA data. Epoch-to-epoch correlations were higher for PAA measures than for PSA data, perhaps indicating greater stability of PSA measures across epochs of sleep. In Experiment 2, PSA and PAA data were compared in 17 unmedicated outpatients with unipolar depression. Canonical correlations and regression analyses indicated that the overlap in variance between PSA and PAA did not exceed 50%, regardless of whether PSA or PAA variables were used as predictors. Epoch-to-epoch correlations between PAA measures were significantly higher than correlations among PSA variables, again suggesting greater stability of PAA data across epochs of sleep. The range of correlations for either data set was, however, substantially lower in the depressed than in the normal group. Experiment 3 evaluated the possibility that filter settings and artifact-rejection procedures had contributed to reduced overlap in PSA-PAA variance and reduced stability in depressed patients. An additional group of eight healthy volunteers served as subjects. Findings in Experiment 3 indicated that methodological differences between Experiments 1 and 2 did not account for the reduced correlations in the depressed group. It was concluded that PSA and PAA data should be comparable in normal subjects but are relatively independent in depressed patients. Epoch-to-epoch correlations were higher for PAA data than those found between PSA measures in both normal subjects and depressed patients, suggesting that PAA may be more stable across sleep epochs. Reduced stability may be a reflection of nonstationarity in the EEG of depressed patients.

The use of Procrustes Target Analysis to discriminate dominant source regions of fine sulfur in the western U.S.A.

Receptor modeling, using Procrustes Target Analysis (PTA), was applied to a fine sulfur data set to discriminate dominant sources and areas of influence in the western U.S.A. The work presented in this note is closely linked to a paper published by Malm et al. ( Atmospheric Environment 24, 3047–3060, 1990), which used two different analyses, area of influence analysis (AIA) and rotated principal component analysis (RPCA), to show similar areas of influence for most source regions in the western U.S.A. A critical examination of RPCA revealed that two issues might confound interpretations. These are (i) eigenvalue degeneracy combined with trying to fit nine orthogonal dimensions pairwise in the PC space and (ii) statistical issues related to missing data and eigenvector truncation. In determining how much of the AIA results are present in the data spanned by the PC space, our findings indicated a 164% improvement in the variance overlap when PTA was substituted for RPCA.

Canonical/redundancy analyses of the Sixteen Personality Factor Questionnaire, the Motivation Analysis Test, and the Eight State Questionnaire

The present study investigated the measurement overlap between the Sixteen Personality Factor Questionnaire (16PF), the Motivation Analysis Test (MAT), and the Eight State Questionnaire (8SQ). These multivariate instruments pertain to the psychological domains of personality, motivation and mood respectively. Canonical/redundancy analysis (Stewart & Love, 1968) was employed on a sample of 258 Australian college students for the 8SQ/MAT measures, and on a subsample of 135 students for the 16PF/MAT and 16PF/8SQ measures. Results demonstrated a marginal overlap in measurement variance for the 16PF and 8SQ, while only very slight redundancy was observed for the 16PF/MAT and 8SQ/MAT intersections. It was concluded that all three instruments are efficient measures of essentially separate psychological modalities.

Quantitative description of sleep stage electrophysiology using digital period analytic techniques.

The purpose of the current study was to assess the overlap in variance of two procedures for the quantification of sleep electrophysiology: conventional stage scoring and computer quantification of tonic activity. Data were collected on 24 nights from eight subjects and were scored according to a modified set of Rechtschaffen and Kales criteria and submitted to a period-analytic computer analysis. Following this, discriminant function analyses were performed on the data for each night to predict the visual stage scores from the computer-generated data. The results indicate a very high degree of predictive accuracy (91.05%) supporting the contention that the computer-quantified data set includes the variance normally captured by stage scoring. The implications of computer quantification of sleep electrophysiology are discussed.

QUESTIONNAIRE VALIDATION BY CONFIRMATORY FACTOR ANALYSIS: AN IMPROVEMENT OVER MULTITRAIT‐MULTIMETHOD MATRICES*

ABSTRACTThe Campbell and Fiske criteria for assessing the construct validity of multitrait‐multimethod (MTMM) matrices has had a long history of use. While various statistical techniques, including ANOVA, have attempted to provide rigor to the MTMM matrix design, numerous problems still remain unsolved. Part of the problem in using an MTMM matrix is the assumption of measurement independence. This study attempts to illustrate the misleading inferences that often occur from MTMM analysis when method variance overlap is not accurately assessed. Three questionnaires were designed that were not method independent. Traditional procedures for assessing MTMM matrices suggested the three scaling formats used were not burdened with unusual method variance. A reanalysis of the MTMM matrix employing a Confirmatory Factor Analysis technique illustrated that method variance was a problem. Finally, the need for studies that concentrate on the nature of method variance, its causes and effects, is discussed.

Interrelationships among Interests, Life-History, and Educational Criteria

The relationship between measures of vocational interest, life history data, and two major educa tional criteria—performance and number of courses taken by area—was explored in a university sample of 1,900 students. Canonical correlation analysis was used to uncover and to describe the major rela tionships between the variable sets. The largest and most important dimension emerging was a general academic achievement dimension. Indices of vari ance overlap suggested that background data, rather than vocational interests, exhibited a stronger relationship with the educational criteria.

Sex Correlates of Adjectives in the Current Activity Vector Analysis

Job tide, age, years of education, race, applicant/incumbent status and site of AVA administration were used to match 59 pairs of Form D Placement Analysis (adjective checklists) for males and females from a wide business and industrial population. The sex dichotomy was correlated ( rtet) with check/no-check responses to each of 81 words appearing on the checklist. Estimates of variance overlap for sex vs item responsivity were obtained. All but two items showed negligible to very small amounts of overlap. The conclusion was drawn that AVA Form D is free from sex stereotyping.

The Factor Compatibility and Communality of Coded-Expressed and Inventoried Interests

An investigation of the relationships and underlying constructs between expressed and inventoried interests across the occupational classification scheme of Holland, Roe and Strong was undertaken. The canonical correlations calculated on each scheme were statistically significant, yet the redundancy indices demonstrated a relatively low amount of variance overlap. The canonical factor structures that were calculated indicated two similar bipolar structures underlying the occupational schema studied.

Expectancy for Successive Elements: Key Ingredient to Language Use

ABSTRACT Language is viewed as an abbreviatory system whereby human processing of information is facilitated through sequential coding. The key ingredient to successful use of language is the ability to anticipate elements in sequence. This is true for encoding operations as well as for decoding. It is argued that the element of expectancy is the underlying factor which accounts for the overlap in variance on language tests requiring various modes of verbal processing. The notion of expectancy applies to theories of language learning and methods of language teaching. If the native speaker's knowledge of his language is characterized as a grammar of expectancy that incorporates pragmatic knowledge of the world, the problem of teaching a second language can be defined as providing the student with a corpus of language in meaningful communicative settings. A major objective is to allow the student to take full advantage of previously acquired expectations about situations and events in the world while he is learning a new grammar of expectancy for the coding of information.