Small sample analysis of vision measurement error

2015 ◽  
Author(s):  
Dan Li ◽  
Zhongyu Wang
Keyword(s):  
Measurement Error ◽  
Small Sample ◽  
Sample Analysis ◽  
Vision Measurement

scholarly journals Psychometric properties of the Neuropsychiatric Inventory: a review

2019 ◽  
Author(s):  
Toni Saari ◽  
Anne Koivisto ◽  
Taina Hintsa ◽  
Tuomo Hänninen ◽  
Ilona Hallikainen
Keyword(s):  
Clinical Trials ◽  
Measurement Error ◽  
Construct Validity ◽  
Psychometric Properties ◽  
Outcome Measurement ◽  
Neuropsychiatric Symptoms ◽  
Practical Importance ◽  
Reliability And Validity ◽  
Small Sample ◽  
Neuropsychiatric Inventory

Neuropsychiatric symptoms (NPSs) cause a significant burden to individuals with memory disorders and their families. Insights into the clinical associations, neurobiology, and treatment of NPSs are largely dependent on informant questionnaires, such as the commonly used Neuropsychiatric Inventory (NPI). Like any scale, the utility of the NPI relies on its psychometric properties, but unlike many scales, the NPI faces unique challenges related to its skip-question and scoring formats.We examined and reviewed the psychometric properties of the NPI in a framework including psychometric properties pertinent for construct validation, and health-related outcome measurement in general. We found that aspects such as test-retest and inter-rater reliability are major strengths of the NPI in addition to its flexible and relatively quick administration. These properties are desired in clinical trials. However, it seems that the reported properties cover only some of the generally examined psychometric properties, representing perhaps necessary but not sufficient reliability and validity evidence for the NPI. There appear to be significant gaps in psychometric data, at least partially owing to small sample sizes in the studies that preclude more comprehensive analyses. Regarding construct validity, only one study examined structural validity with the NPI subquestions. Measurement error was not assessed in the reviewed studies. For future validation, we recommend using data from all subquestions, collecting larger samples, paying specific attention to construct validity and formulating hypotheses a priori. As the NPI is an outcome measure of interest in clinical trials, examining measurement error could be of practical importance.

Small sample analysis of a platform vibration via bootstrap method

2010 ◽  
Author(s):  
Zhongyu Wang ◽  
Jianyong Sun ◽  
Jianjun Zhang ◽  
Xintao Xia
Keyword(s):  
Bootstrap Method ◽  
Small Sample ◽  
Sample Analysis

THE ASSAY OF CORTICOTROPHIN IN MICE

1963 ◽  
Vol 44 (2) ◽  
pp. 237-249 ◽  
Author(s):  
Claus Rerup ◽  
Pavo Hedner
Keyword(s):  
Subcutaneous Administration ◽  
Small Sample ◽  
Lower Body ◽  
Sample Analysis ◽  
Lower Body Weight ◽  
Increased Sensitivity ◽  
The Mean ◽  
The Difference ◽  
Response Line ◽  
Free Plasma

ABSTRACT The assay of corticotrophin was performed in mice by means of small sample analysis of free plasma corticosteroids. In this method hypophysectomy was replaced by dexamethasone pretreatment. The response was measured preferably in a single mouse weighing 20 g or more. When mice of a lower body weight were used the plasma of two randomly assigned mice was pooled. Corticosteroids (mainly corticosterone) were determined fluorometrically in 0.25 (0.20) ml samples of plasma from heparinized blood. The results show that valid corticotrophin assays can be performed in mice both by the intravenous and subcutaneous route. Compared with the adrenal ascorbic acid depletion method or the plasma corticosteroid method in the rat the assay in mice was found to be at least five times more sensitive. 40 micro-units of corticotrophin were consistently detectable. Precision was dependent on the route of administration, the mean index of precision (s/b) being 0.20 in the intravenous and 0.12 in the subcutaneous assay. The difference was due to a steeper slope of the logdose-response line after subcutaneous administration. Contrary to the findings in the rat, corticotrophin A (oxycel purified) did not differ significantly in potency estimates from subcutaneous and intravenous assays in mice, when crude corticotrophin (U. S. P. Corticotropin Reference Standard) was the basis of comparison. Accordingly results of subcutaneous assays of corticotrophin A samples in terms of the U. S. P. standard were lower in mice than in rats. The use of gelatine instead of saline as diluent in the subcutaneous assays yielded slightly but not significantly higher potency estimates (25 per cent). The interpretation of the results is that for intravenous corticotrophin assays the mouse method is comparable to the rat assay. For subcutaneous corticotrophin assays, however, the mouse method is not suitable, if crude corticotrophin (U. S. P. standard) is the basis of comparison, but if corticotrophin A (oxycel purified) is the standard of reference (e. g. the Third International Standard for Corticotrophin), the mouse method may justifiably be used. The advantages of the mouse method are increased sensitivity, precision, convenience, and economy.

scholarly journals Geographic Variation of the Curve-Billed Thrasher (Toxostoma Curvirostre) Complex

The Auk ◽  
2003 ◽  
Vol 120 (2) ◽  
pp. 311-322
Author(s):  
Octavio R. Rojas-Soto
Keyword(s):  
Measurement Error ◽  
Small Sample Size ◽  
Morphological Characters ◽  
Color Pattern ◽  
Small Sample ◽  
Sierra Madre Occidental ◽  
Geographic Patterns ◽  
Western Group ◽  
Sierra Madre ◽  
The Mean

Abstract Geographic patterns of variation in morphological characters in the Curve-billed Thrasher (Toxostoma curvirostre) have been recognized by the description of seven subspecies. Twelve standard measurements, as well as three colorimetric characters and two color pattern characters, were analyzed to test whether subspecies limits predict patterns of variation. Measurement error was addressed by measuring each character three times and calculating the mean. A total of 821 male study skins were used, representing 29 locations. A variety of analysis revealed two major groups, an eastern and western group, divided by the Sierra Madre Occidental. Those two groups had previously been recognized as the curvirostre and palmeri groups, respectively. Those groups were also recovered by analysis of mtDNA. The two groups fulfill the requirements for species. The Tiburón Island (T. c. insularis) sample was distinct for several characters; however, small sample size precludes formal taxonomic recommendation. Within the two major groups, most characters showed incongruent clinal patterns of variation that did not match subspecies limits.

Vision measurement error analysis for nonlinear light refraction at high temperature

2018 ◽  
Vol 57 (20) ◽  
pp. 5556 ◽  
Author(s):  
Huaxia Deng ◽  
Fei Wang ◽  
Jin Zhang ◽  
Guoce Hu ◽  
Mengchao Ma ◽  
...  
Keyword(s):  
High Temperature ◽  
Measurement Error ◽  
Error Analysis ◽  
Light Refraction ◽  
Vision Measurement

Using Longitudinal Data to Model Teachers' Ratings of Classroom Behavior as a Dynamic Process

1981 ◽  
Vol 6 (3) ◽  
pp. 237-255 ◽  
Author(s):  
Ian Plewis
Keyword(s):  
Measurement Error ◽  
Longitudinal Data ◽  
Dynamic Process ◽  
Categorical Data ◽  
Continuous Time ◽  
Classroom Behavior ◽  
Markov Models ◽  
Time Measurement ◽  
Small Sample ◽  
Educational Implications

Simple Markov models are fitted to a small sample of longitudinal categorical data of teachers' ratings of children's classroom behavior. Although the data consist only of observations at 5 occasions, it was possible, after dividing the data into two groups, to fit plausible models in continuous time. Measurement error and alternative longitudinal designs are discussed, and some possible educational implications are noted.

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