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At least 253 records · Page 14Linked to original sources
PubMed1978

Principles for identifying structural differences. Some methodological issues related to comparative factor analysis.

Several recent articles published in the Journal of Gerontology have been concerned with changes in factor structure of various psychological, social, and medical fitness measures. The present article reviews four principles for comparing structures and evaluates several recent articles in terms of these principles. The four principles are concerned with resolving: (1) problems of metric, (2) problems of rotation to similarity, (3) the number of factors problem, and (4) problems related to different extraction or rotational procedures across comparison groups. Utilization of a different metric in each correlation matrix implies that results may be a simple artifact of a different metric for each group. Failure to rotate to similarity and insufficient care with regard to the number of factors problem may result in artificially dissimilar structures. Finally, in comparing results across studies, differences in extraction or rotational procedures across different studies may result in differing results as artifacts of the methods employed.

Factor Analysis, Statistical↗
PubMed1982

Reliability of measuring trunk motions in centimeters.

A method of measuring trunk motion and two related motions using a tape measure and a stepstool was developed by physical therapists at our hospital. The purpose of this study was to assess the reliability of this method. Three repetitions of six motions performed by 24 subjects were each measured by three physical therapist raters on two separate days. The motions were forward bending, backward bending, right side bending, right rotation, right straight leg raising, and right prone knee bending. Reliability, standard deviation, and standard error were calculated for each motion. Only forward bending exhibited good single measurement reliability. Reliability coefficients for all motions were higher for the average of three successive measurements or for the measurement of a motion on successive days by the same rater. Measurements of rotation and straight leg raising, despite the improvement, continued to have low reliability. Analysis of variance was used to determine the significance of the differences between means for each motion across three raters, three repetitions, and two days. By looking at the analysis of variance and reliability estimates together, the authors identified two types of constant error affecting the data.

Adult↗
PubMed2003

The effect of leg length discrepancy on spinal motion during gait: three-dimensional analysis in healthy volunteers.

STUDY DESIGN: This study focused on the effects of leg length discrepancy on the motion of the normal spine during gait in healthy male volunteers who wore a heel-raising orthotic device on the right foot. OBJECTIVE: To evaluate the effect of leg length discrepancy on the changes in curvature of the normal spine during gait. SUMMARY OF BACKGROUND DATA: There are few published data on the effects of leg length discrepancy on the motion of the normal spine during gait. METHODS: An orthotic device that raised the heel by 3 cm was used to simulate leg length discrepancy. Twenty-two healthy male volunteers participated (age: 28.2 +/- 6.1 years, average +/- SD). The dynamic curvatures of the spine under two conditions (without and with a heel-raising orthotic device; normal gait and heel-raising gait) were evaluated during gait. The leg length discrepancy values without and with the device were measured and analyzed using a VICON system (Oxford Metrics, United Kingdom). RESULTS: The spine showed an asymmetrical lateral-bending motion during heel-raising gait as compensation for the leg length discrepancy. Maximum lateral bending angle of the thoracic spine was 4.2 +/- 1.4 degrees in heel-raising gait, whereas it was 3.0 +/- 1.0 degrees in normal gait. Maximum lateral bending angle of the lumbar spine was 8.1 +/- 2.8 degrees in heel-raising gait, whereas it was 6.1 +/- 2.1 degrees in normal gait. The maximum bending angle and bending velocity were significantly larger in the heel-raising gait than in normal gait. CONCLUSION: Patients who have leg length discrepancy due to disorders in the lower extremities are at greater risk of developing disabling spinal disorders due to exaggerated degenerative change. Therefore, treatment for leg length discrepancy may be helpful in preventing degenerative spinal changes.

Adult↗
PubMed1985

Toward a more objective approach to pupil assessment.

The findings of an investigational study comparing a hand held tongue depressor pupil gauge with a printed millimeter scale sheet are the focus of this article. A historical perspective of the development of various millimeter measurement scales and devices is included as well as a brief overview of the anatomy and physiology of the oculomotor (III) cranial nerve. The results of the study provide support for the use of millimeter scales as an effective means of measurement of pupil size. Increased reliability with the use of a hand held tongue depressor pupil gauge is demonstrated. Implications for nursing practice are summarized.

Humans↗
PubMed2005

Comparative analysis of population genetic structure in Athyrium distentifolium (Pteridophyta) using AFLPs and SSRs from anonymous and transcribed gene regions.

To examine the performance and information content of different marker systems, comparative assessment of population genetic diversity was undertaken in nine populations of Athyrium distentifolium using nine genomic and 10 expressed sequence tag (EST) microsatellite (SSR) loci, and 265 amplified fragment length polymorphism (AFLP) loci from two primer combinations. In range-wide comparisons (European vs. North American populations), the EST-SSR loci showed more reliable amplification and produced more easily scorable bands than genomic simple sequence repeats (SSRs). Genomic SSRs showed significantly higher levels of allelic diversity than EST-SSRs, but there was a significant correlation in the rank order of population diversities revealed by both marker types. When AFLPs, genomic SSRs, and EST-SSRs are considered, comparisons of different population diversity metrics/markers revealed a mixture of significant and nonsignificant rank-order correlations. However, no hard incongruence was detected (in no pairwise comparison of populations did different marker systems or metrics detect opposingly significant different amounts of variation). Comparable population pairwise estimates of F(ST) were obtained for all marker types, but whilst absolute values for genomic and EST-SSRs were very similar (F(ST) = 0.355 and 0.342, respectively), differentiation was consistently higher for AFLPs in pairwise and global comparisons (global AFLP F(ST) = 0.496). The two AFLP primer combinations outperformed 18 SSR loci in assignment tests and discriminatory power in phenetic cluster analyses. The results from marker comparisons on A. distentifolium are discussed in the context of the few other studies on natural plant populations comparing microsatellite and AFLP variability.

Cluster Analysis↗
PubMed2006

Metric assessment of the "mastoid triangle" for sex determination: a validation study.

Recently, a metric approach to skeletal sex determination was published by Paiva and Segre which is based on the summation of two triangular areas defined by three distinct craniometric landmarks: Porion, Mastoidale, and Asterion. According to the authors, values for the total triangle > or =1447.40 mm(2) are characteristic for male crania, while values < or =1260.36 mm(2) are indicative of female skulls (95% confidence). In order to evaluate the method's validity, two sex- and age-documented samples of different provenience were analyzed (N=197). The results show that while the indicated measurements display significant sex differences, the technique is of little practical meaning where a single individual must be independently classified. It is hypothesized that differences in the expression of sexual dimorphism as well as a population-specific variability of the asterion location undermine the value of the mastoid triangle as a sex determinant.

Adult↗