Some comments on selecting the best of several binomial populations or the bivariate normal population having the largest correlation coefficient

Psychometrika ◽  
1978 ◽  
Vol 43 (1) ◽  
pp. 127-128 ◽  
Author(s):  
Rand R. Wilcox
Keyword(s):  
Correlation Coefficient ◽  
Normal Population ◽  
Bivariate Normal ◽  
Binomial Populations

Effects of Scaling on the Correlation Coefficient: Additional Considerations

1978 ◽  
Vol 15 (2) ◽  
pp. 304-308 ◽  
Author(s):  
Warren S. Martin
Keyword(s):  
Normal Distribution ◽  
Correlation Coefficient ◽  
Correlation Coefficients ◽  
Bivariate Normal Distribution ◽  
Information Loss ◽  
Simulation Data ◽  
Pearson Product Moment Correlation ◽  
Bivariate Normal ◽  
Amount Of Information ◽  
Restricted Number

Distortion in the Pearson product moment correlation due to a restricted number of scale points is evaluated in two ways. First, a simulation of the bivariate normal distribution is used to estimate the effects of varying the number of scale points on the product moment correlation. This procedure demonstrates a substantial amount of information loss. Second, other correlation coefficients and some methods to correct for this loss are discussed and related to the simulation data.

scholarly journals The Evaluation of Trochlear Osseous Morphology: An Epidemiologic Study

2020 ◽  
Vol 8 (7_suppl6) ◽  
pp. 2325967120S0044
Author(s):  
Sercan Yalçin ◽  
Gabriel Onor ◽  
Scott Kaar ◽  
lee Pace ◽  
Paolo Ferrua ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Normal Population ◽  
Trochlear Dysplasia ◽  
Interobserver Reliability ◽  
Intraclass Correlation ◽  
Epidemiologic Study ◽  
Intraobserver Reliability ◽  
Severe Dysplasia ◽  
Mild Dysplasia ◽  
Study Population

Objectives: The purpose of this study is to investigate the prevalence of the trochlear dysplasia in our study population. Methods: We obtained 692 skeletally mature femoral specimens from the [Blinded Institution], [Blinded Collection]. Five observers were asked to evaluate each specimen for trochlear dysplasia on a scale between 0 and 3 (0 – normal/no dysplasia; 1 – mild dysplasia; 2 – moderate dysplasia; 3 – severe dysplasia). Each observer made initial evaluations for interobserver reliability. Each observer then re-evaluated each specimen one month later to determine intraobserver reliability. We evaluated inter and intraobserver reliability utilizing intraclass correlation coefficient (ICC). All statistics were performed with SPSS v.25 (IBM, USA). Results: The interobserver ICC of first and second evaluation of all observers were found to be 0.906 [0.894-0,916] and 0.904 [0.892-0.915], respectively. The intraobserver ICC of observers were as follows: Reviewer1: 0.799 [0.771-0.825]; Reviewer2: 0.686 [0.645-0.724]; Reviewer3: 0.808 [0.781-0.832]; Reviewer4: 0.787 [0.757-0.814]; Reviewer5: 0.778 [0.747-0.806]. These results show intra and interobserver correlation was good to excellent. The percentages of normal trochlea, mild dysplasia, moderate dysplasia and severe dysplasia for first evaluation, by reviewer, are as follows: Reviewer 1: 82.7%, 12.1%, 4.0%, 1.2%; Reviewer 2: 37.3%, 26.2%, 27.5%, 9.1%; Reviewer 3: 57.9%, 28.0%, 12.1%, 1.9%; Reviewer 4: 64.2%, 25.6%, 7.7%, 2.6%; Reviewer 5: 65.6%, 14.9%, 12.3%, 7.2%. The percentages of normal trochlea, mild dysplasia, moderate dysplasia and severe dysplasia for second evaluation, by reviewer, are as follows: Reviewer 1: 78.8%, 16.6%, 3.6%, 1.0%; Reviewer 2: 40.3%, 26.4%, 23.3%, 10.0%; Reviewer 3: 42.2%,35.1%, 18.8%, 3.9%; Reviewer 4: 57.4%, 31.9%, 8.2%, 2.5%; Reviewer 5: 73.7%, 8.2%, 9.7%, 8.4%. In total, the percentages of normal trochlea, mild dysplasia, moderate dysplasia and severe dysplasia were 60.00%, 22.51%, 12.72%, 4.77%; respectively. Conclusions: This study shows that although there was no absolute criteria to grade trochlear dysplasia, observers had similar opinions on the degree of dysplasia. Also, our cohort shows that moderate to severe dysplasia is not uncommon as it is present in around 17% of knees in our cohort. This is the first epidemiologic study evaluating the prevalence of trochlear dysplasia in the normal population.

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