Relationships between isoinertial lumbar dynamometry parameters and demographic parameters in chronic low back pain patients

The purpose of this study was to investigate which demographic parameters are most important in relation to lumbar dynamometry performance in patients with chronic low back pain (LBP). Forty-five chronic LBP patients participated in this study. Gender, age, weight and height were determined and a lumbar dynamometry measurement was carried out, using the Isostation B200. Student's t-test, ANOVA techniques and correlation coefficients were used to investigate the relationships between each demographic parameter and lumbar dynamometry performance. Stepwise multiple linear regression analyses were performed afterwards to determine which demographic parameters are most important in relation to lumbar dynamometry performance. Results indicate significant relationships (1) between gender, height, weight and all lumbar dynamometry parameters and (2) between age and three of the six isometric torque parameters. No significant relationship was found between age and maximum velocity parameters. Results of the stepwise multiple linear regression analyses show that the demographic parameters explain 27-47% of the variance in maximum isometric strength parameters and 19-25% of the variance in maximum velocity parameters. Gender is the most important demographic parameter, being related to nearly all maximum isometric torque parameters (percentage explained variance 6-37%) and height is the only important demographic parameter related to the velocity parameters (percentage explained variance 19-25%). Weight and age account for only a small amount of variance in lumbar dynamometry parameters (percentage explained variance 5-7%), meaning that these parameters are non-relevant predictors.     

Right versus left symmetry of ulnar variance. A radiographic assessment

One hundred skeletally mature healthy volunteers underwent standardized bilateral posteroanterior radiographs in unloaded (static) and loaded (dynamic) conditions to determine the symmetry of ulnar variance. The mean age was 32 +/- 9 years (range, 19-61 years), with 58 women and 42 men. Ulnar variance was measured to the closest 0.5 mm using the method of perpendiculars. Three separate measurements were made of each radiograph in a blinded fashion by the same investigator. An intraobserver standard deviation of 0.21 was used to calculate a 95% tolerance interval of 0.7 mm (rounded up to 1 mm) as a measure of significance. The average static ulnar variance was -0.13 +/- 1.5 mm on the left and -0.29 +/- 1.6 mm on the right. The average dynamic ulnar variance was 0.93 +/- 1.5 mm on the left and 0.82 +/- 1.5 mm on the right. When compared individually, there was a greater than or equal to 1 mm side to side difference in 37% of volunteers under static and 38% under dynamic conditions. There were no significant correlations between ulnar variance measurements and patient age, gender, race, or handedness. Use of the normal wrist radiograph as a baseline for static radial length measurements is valid in only 63% of cases.     

Physique as a risk factor for ulnar variance in elite female gymnasts

The aims of this study were: 1) to determine ulnar variance variability of elite, female gymnasts; 2) to evaluate the relationship between ulnar variance and physique, maturity status, and training characteristics of these gymnasts. All 156 skeletally immature female gymnasts were participants at the World Championships Artistic Gymnastics, Rotterdam, The Netherlands, in 1987. Chronological ages varied between 13.1 and 20.6 yr (mean = 15.9 +/- 1.3 yr). A large set of anthropometric dimensions was taken and somatotype was determined by the Heath-Carter technique. Skeletal age was assessed by the Tanner-Whitehouse II method. Menarcheal status and training data were collected by questionnaire. Ulnar variance was determined according to Hafner et al. Gymnasts differ significantly from reference girls with respect to physique and maturational status: gymnasts were smaller and delayed in skeletal maturity with about 1.5 yr. For those who had attained menarche, mean age at menarche was 15.1 +/- 1.3 yr. Ulnar variance shows a normal distribution in the gymnasts, ranging from -10.5 mm to +5.9 mm, which is somewhat more positive, i.e., an ulnar overgrowth, than reference wrists. The relationship between ulnar variance and somatic and maturational features suggests that female gymnasts who are more mature and have a physique characterized as relatively tall with a high lean body mass are at greater risk for developing a positive ulnar variance. No relationship between ulnar variance and training characteristics was evident. It is concluded that the observed positive ulnar variance in this sample of elite female gymnasts is less pronounced than originally stated in most "case reports."     

Multivariate study of the patient-therapist system: A replication and extension.

Replicates and extends the work of R. H. Moos and S. R. Clemes (see record 1967-07395-001) and F. van der Veen (see record 1965-08090-001). Each of 6 patients saw each of 4 therapists twice. The variables total activity, feeling words, action words, reinforcements each was scored separately for patient and therapist for each interview. Patient problem expression and therapist accurate empathy were rated for each interview. Consistent differences between patients accounted for substantially more variance than consistent differences between therapists on all variables. Patient * Therapist * Session interactions generally accounted for large proportions of the total variance. Results indicate that the therapist behaviors studied were not the result of a trait, of a given tendency to be empathic, or of a consistently applied therapeutic technique, but rather were very substantially situationally or patient determined. (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some problems in the nonorthogonal analysis of variance.

Contends that nonorthogonal analysis of variance has been much misunderstood by psychologists, and as a result there has been considerable controversy as to the appropriate methods of analysis. These problems traditionally associated with the nonorthogonal multifactor analysis of variance are rather easily resolved by viewing the analysis of variance (either orthogonal or nonorthogonal) as a series of model comparisons. From this point of view, the analysis of highly confounded designs is seen to yield results that correspond to those that a purely logical analysis would suggest. A logical flow of comparisons and decisions is developed for both the 2- and 3-factor designs that, although more complicated than procedures previously proposed, seems necessary for drawing proper inferences. It is further shown that there is no logical difference between orthogonal and nonorthogonal analysis of variance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molecular analysis of the Drosophila catalase gene

OBJECTIVE: To determine whether genetic and non-genetic components of interindividual variation in systolic and diastolic blood pressure are constant throughout the day or are time or activity dependent. METHODS: We obtained 24 h ambulatory blood pressure recordings in 263 members of 68 unrelated nuclear families (i.e. parents and their offspring) representative of the Caucasian population of Rochester, MN, USA. Using the time each patient got into bed as a reference point, we identified 198 records in which this reference point was preceded by eight consecutive active hours (out of bed) and followed by four consecutive inactive hours (in bed) in which four or more blood pressure readings taken each hour were judged to be technically satisfactory. For each hourly mean for systolic and diastolic blood pressure, we estimated total interindividual variance, variance associated with concomitant variables (generation; sex within generation strata; and age, height, weight, body mass index, and abdomen-to-hip ratio within generation and sex strata), and variance associated with additive genetic effects (i.e. the chief cause of resemblance between relatives). To assess trends in each component of interindividual blood pressure variance over the 12 h period, we estimated the slope of the linear regression line fit to the hourly estimates. RESULTS: For systolic blood pressure, total interindividual variance did not change significantly (slope of regression line = -0.23, P = 0.717). In contrast, total interindividual variance for diastolic blood pressure was greater during active hours than inactive hours (slope of regression line = -5.53, P < 0.001). For both systolic and diastolic blood pressure, variance associated with the concomitant variables was greater during active hours than during inactive hours (for systolic blood pressure slope of regression line = -2.98, P = 0.001; for diastolic blood pressure slope of regression line = -6.14, P < 0.001). Likewise, for both systolic and diastolic blood pressure, variance associated with additive genetic effects was also greater during active hours than during inactive hours (for systolic blood pressure slope of regression line = -1.65, P = 0.090; for diastolic blood pressure slope of regression line = -1.47, P = 0.018). CONCLUSIONS: This study demonstrates that components of interindividual variation in blood pressure are not constant, but are time or activity dependent.     

Bias in validity generalization variance estimates: A reply to Hoben Thomas.

In a recent article H. Thomas (see record 1989-10691-001) derived the expected value of the true validity variance estimate used in validity generalization studies. Based on computations of the expected values for certain scenarios, Thomas made a number of critical assertions regarding the variance estimate. This article shows that Thomas's arguments regarding deficiencies in the variance estimate used in the validity generalization studies are misleading. Contrary to Thomas's extremely negative assessment of the situation, there is no really convincing reason to doubt or abandon the estimates of true validity variance obtained in applied research from the Callender-Osborn and other closely related methods. Rather, there is strong evidence to indicate that populations of true validities with meaningful differences in mean and variance can be reliably distinguished, provided that a sufficient amount of base data are available. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The heritability of intelligence: Neither known nor unknown.

Comments on "The Genes and Intelligence" section of the U. Neisser et al (see record 83-26553) American Psychological Association (APA) Task Force Report on Intelligence. At issue is the discussion of partitioning phenotypic variance, a discussion which the author claims is not complete. A more detailed review of variance components would have great implications for the interpretation of heritability coefficients applied to intelligence. The vast differences between populations in environmental variability and the resulting extreme relativity of heritability estimates for intelligence would make them of limited use for prediction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A note on variance explained in the mixed analysis of variance models.

Examines assumptions about the general linear model for interaction terms in the mixed analysis of variance. Some well-known results of S. R. Searle (1971) demonstrate that the inconsistencies between J. H. Dwyer's (see record 1975-02166-001) technique and that of G. M. Vaughn and M. C. Corballis (see record 1969-16617-001) in estimating the magnitude of effect for a mixed interaction are the direct result of specific assumptions made. If it is assumed that the interaction source of variance is a random variable, then the equations obtained by Vaughn and Corballis are correct; however, if an alternative assumption is made (i.e., that the iteraction term is fixed in one direction), then Dwyer's equations are correct. Researchers are called on to be cognizant of these two sets of assumptions and to be aware of the dramatic effects they may have on estimates of magnitude of effect for mixed interactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Signal probability and the slope of the ROC: A comment on Treisman.

Argues that there is an error in the derivation by M. Treisman (see record 1977-26741-001) of a theory to explain the finding of a positive association between the probability of signal presentation and the slope of the receiver operating characteristic (ROC). An alternative suggestion is proposed. Like Treisman's, it is based on changes in the variance of the threshold criteria. (2 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Construct Validity of the PASS Theory and CAS: Correlations With Achievement.

The relationship among Planning, Attention, Simultaneous, and Successive (PASS) processing scores of the Cognitive Assessment System (CAS) and the Woodcock-Johnson Revised Tests of Achievement (WJ-R) were examined with a sample of 1,559 students aged 5-17 years. Participants were part of the CAS standardization sample and closely represented the U.S. population on a number of important demographic variables. Pearson product-moment correlation between CAS Full Scale and the WJ-R Skills cluster was .71 for the Standard and .70 for the Basic CAS Battery scores, providing evidence for the construct validity of the CAS. The CAS correlated with achievement as well if not better than tests of general intelligence. The amount of variance in the WJ-R scores the CAS accounted for increased with age between 5- to 13-year-olds. The 4 PASS scale scores cumulatively accounted for slightly more of the WJ-R variance than the CAS Full Scale score. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control of halo error: A multiple regression approach.

Comments on an article by F. J. Landy et al (see record 1981-00274-001) that suggests a method for excluding halo variance in rating scales. It is argued that this approach may result in excluding true variance. The present article presents a conceptualization of the halo effect in terms of a suppressor variable. Accordingly, a multiple regression approach for the treatment of halo variance is suggested. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Counselor orientation and theoretical attitudes toward counseling: Historical perspective and new data.

Based on the the continued citation of F. E. Fiedler's (see record 1952-00943-001) conclusions about counselor's attitudes being a function of theoretical orientation and experience, 54 counselors from behaviorist, Gestalt, and rational-emotive orientations were compared on 4 subscales of an orientation questionnaire. Results show a significant relationship between counselor orientation and theoretical tenets; level of experience did not contribute significantly to within-groups variance. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiplicative validity generalization model: Accuracy of estimates as a function of sample size and mean, variance, and shape of distribution of true validities.

Used simulation techniques to study the accuracy of estimates of the mean, variance, and lower credibility value of true validities produced by the independent multiplicative model and by a modified dependent model that takes the correlation between range restriction and criterion reliability artifacts into account. Sample sizes (n?=?50 or 100) and the number of studies/analyses (50) were selected to be consistent with the typical parameters found in 129 validity generalization analyses. The mean, standard deviation, and shape of the true validity distributions were systematically varied. It is concluded that the independent and modified dependent estimates were typically accurate, although the credibility estimates were affected by the extremely skewed distributions. The mean and variance estimates from both models were not affected by distribution shape. Results support the applicability of the 1st 2 authors' (see record 1981-27033-001) models and F. L. Schmidt and J. E. Hunter's (see record 1978-11448-001) noninteractive model. Some limitations of the "bare-bones" sampling-error-only approach are noted. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correlation between genetically matched groups versus reliability theory: A reply to Jensen.

Argues that A. Jensen's (see record 1971-09170-001) proposal for interpreting phenotypes as direct proportional measures of phenotype variance attributable to trait heritability would lead to an overestimation of variance attributable to genetic factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of acceleration subjects to other populations: spinal anomaly distribution

Prior studies demonstrate an inconsistent relationship between occupational inorganic lead exposure and simple reaction time (SRT) performance. In this study, we administered a computerized SRT test to 78 currently employed lead smelter workers and then investigated the relationship between different measures of blood lead and components of SRT performance. The measures of blood lead included current blood lead (PbB) and mathematically derived blood lead fractions from the environment (PbB-env) and from bone (PbB-bn). Measures of SRT performance, obtained from 44 trials with interstimulus intervals (ISIs) ranging from 1 to 10 seconds, included median SRT (SRT-md), mean SRT for ISIs between 1 and 5 seconds (SRT-1-5), and mean SRT for ISIs between 6 and 10 seconds (SRT-6-10). Multiple regression analysis after adjustment for age and education revealed a curvilinear relationship between PbB and SRT-md. As PbB increased from 0 to 30 micrograms dl-1, SRT-md decreased, and only with PbB levels above 30 micrograms dl-1 did SRT-md increase. PbB terms accounted for 13.7% of the variance in this SRT measure (P < 0.01). The longer ISI variable, SRT-6-10, was found to be more strongly related to PbB, to have lesser variability across ISIs, and to be unrelated to age. Additional multiple regression analysis to examine the relationship between components of SRT and the PbB fractions, PbB-env and PbB-bn, showed only PbB-env to account for significant variance in SRT-md, (14.4%, P < 0.01), SRT-1-5 (9.7%, P < 0.03), and SRT-1-6 (15%, P < 0.01). We conclude that the relationship between PbB and SRT is U-shaped, that the SRT measure SRT-6-10 has properties that make it the preferred measure of SRT performance in future studies, and finally that only PbB-env, and not PbB-bn, is related to components of SRT.     

Pretesting as a confounding variable in evaluating an encounter group.

Evaluated the effectiveness of an encounter group designed to enhance relationships between 3 groups of 68 15-21 yr old black inner-city males and 3 groups of 38 white and 2 black policemen and the interaction between pretesting and treatment and its effects on outcome. There were 3 experimental and 3 control groups which either did or did not participate in the pretest and treatment portions of the study; all groups completed the posttest. The 2 evaluation measures were the Alienation Index Inventory and a specially developed projective device; these were administered by white and black Es to same-race groups. Results indicate that the proportion of variance contributed by pretesting is influenced by group membership, treatment, and outcome criterion and is largely unpredictable. It is suggested that such variance be controlled in each experiment. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preliminary evidence that DEXA provides an accurate assessment of body composition

It was previously found that dual-energy X-ray absorptiometry (DEXA) underestimated central body fat. The purposes of this study were to determine whether an updated version (enhanced version 5.64) of the analysis program corrected this problem (experiment 1) and to compare body composition assessed by DEXA and hydrodensitometry (HD) in women (n = 225) and men (n = 110) across a 21- to 81-yr age range (experiment 2). For experiment 1, 10 subjects underwent DEXA procedures in a control condition and with packets of lard positioned over either the thighs or the truncal region. DEXA accurately quantified the additional mass as approximately 96% fat, regardless of position. For experiment 2, DEXA yielded higher (P < 0.001) estimates of fatness than did HD (32.1 +/- 12.0 vs. 31.2 +/- 10.1%). The mean difference between the two methods was similar in young, middle-aged, and older subjects, but was different in men (HD-DEXA, 1.6 +/- 3.4% of body wt) than in women (-2.1 +/- 3.8% of body wt). Correcting the density of fat-free mass for variance in the bone mineral fraction of fat-free mass reduced the difference between the methods in men from 1.6 +/- 3.4 to -0.7 +/- 2.9% but widened it in women from -2.1 +/- 3.8 to -3.5 +/- 3.4%. A second correction procedure that adjusted for variance in water, protein, and mineral fractions of fat-free mass eliminated the differences in estimates of fat content by DEXA and HD in both men (21.1 +/- 9.3 vs. 20.6 +/- 8.4%, respectively) and women (37.5 +/- 9.3 vs. 36.8 +/- 8.0%, respectively). These results provide encouraging, but not definitive, evidence that the assessment of body composition by DEXA is accurate under the specified conditions.