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Results for “Analysis of Variance”

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At least 55 records · Page 3Linked to original sources
PubMed1999

Repeatability and variance analysis on multiple computer-assisted (IVOS) sperm morphology readings.

The repeatability of the Hamilton Thorne Research IVOS (version 10) semen analyser (dimension specific software, version 3) in the evaluation of sperm morphology according to strict criteria was investigated in this study. The repeat measures investigated were cell-cell (300 cells, 3 x each), intraslide (20 slides, 3 x each) and interslide (30 samples, 3 slides each), and their normal sperm morphology outcomes were recorded. Semen samples with varying normal sperm morphology percentages were obtained and sperm morphology slides prepared. The slides were stained with Diff-Quik stain. Agreements between evaluations were determined using the kappa statistic and average coefficients of variation. The predictive probability for an abnormal cell given a prior abnormal cell outcome was 91%, and 89% for a similar prediction of a normal cell. The predictive probabilities for an abnormal or a normal cell given two prior abnormal or two prior normal cell outcomes were 95% and 94%, respectively. No significant bias was obtained between the repeat probabilities for normal and abnormal sperm cells. The average coefficients of variation for the intraslide trial were 9.73% and 8.30% when 100 and 200 sperm cells were evaluated, respectively. The average coefficient of variation for the interslide trial was 15.39%. The technical importance of good sample and slide preparation technique has once again been highlighted by this study. A uniform (spatial homogeneity), high concentration (5-10 cells per computer screen) smear must be made and the cells stained with optimal intensity (maximum contrast). In a trial in which 2000 cells were evaluated, 19 objects (0.95%) were identified as spermatozoa, but were debris. The automated semen analysing system (IVOS) used in this study was shown to maintain a level of repeatability, precision and accuracy acceptable for the application of the system in a routine semen analysis situation.

Analysis of Variance↗
PubMedDate not supplied

The choice between analysis of variance and analysis of covariance with special reference to the analysis of organ weights in toxicology studies.

The problem of when to include a covariate in the analysis of variance is considered in the special case of organ weight analysis in animal toxicology studies. The covariate is bodyweight prior to death, which may be subject to treatment effects. A simulation study is carried out to compare four rules for deciding whether or not to include the covariate. It is concluded that if there is background information which shows a linear relationship between variate and covariate it is advisable to adjust for the covariate, however weak the relationship may appear to be on the current set of data. Alternative procedures lead to unacceptably high Type I error rates.

Analysis of Variance↗
PubMed1995

Segregation analysis and variance components analysis of bone mineral density in healthy families.

Bone mineral density (BMD) was measured in 1992-93 in 129 nuclear families, including 258 parents and 183 children, and was analyzed for familial resemblance factors. BMD measurements were adjusted on weight and age. Segregation analysis rejected the monogenic hypothesis and exhibited a strong polygenic component. Variance components analysis was then used to estimate the parameters of a multivariate normal model including an additive polygenic component, a common environment factor, and a residual specific to each individual. The genetic component was independent of sex and age. The common environmental factor was not significant. The variance of the residual specific factor appeared to be a quadratic function of age, reaching its minimum value at 26.4 years. Consequently, the maximum value for heritability (ratio of genetic variance to total variance) is observed at this age (h2 = 0.84). According to this model, the correlation between two relatives is a function of the ages of each individual in the pair.

Adolescent↗