Determining Sample Sizes for Precise Contrast Analysis With Heterogeneous Variances
نویسندگان
چکیده
منابع مشابه
Standard 4: determining adequate sample sizes.
There are many challenges to be faced when conducting randomized controlled trials (RCTs) in pediatric research. One important challenge is the determination of an appropriate sample size. Recruiting more children than necessary risks unnecessary overexposure of children to an inferior treatment, whereas underestimating the sample required will lead to inconclusive or unreliable results. Both o...
متن کاملExploratory Factor Analysis With Small Sample Sizes.
Exploratory factor analysis (EFA) is generally regarded as a technique for large sample sizes (N), with N = 50 as a reasonable absolute minimum. This study offers a comprehensive overview of the conditions in which EFA can yield good quality results for N below 50. Simulations were carried out to estimate the minimum required N for different levels of loadings (λ), number of factors (f), and nu...
متن کاملEstimating the Correlation in Bivariate Normal Data with Known Variances and Small Sample Sizes().
We consider the problem of estimating the correlation in bivariate normal data when the means and variances are assumed known, with emphasis on the small sample case. We consider eight different estimators, several of them considered here for the first time in the literature. In a simulation study, we found that Bayesian estimators using the uniform and arc-sine priors outperformed several empi...
متن کاملDetermining Optimum Strata Boundaries and Sample Sizes for Skewed Population with Log-Normal Distribution
The method of choosing the best boundaries that make strata internally homogeneous as far as possible is known as optimum stratification. To achieve this, the strata should be constructed in such a way that the strata variances for the characteristic under study be as small as possible. If the frequency distribution of the study variable x is known, the Optimum Strata Boundaries (OSB) could be ...
متن کاملSample Sizes for All Patients With Initial
and power=80%, 1605 patients would be required in each group. If power=90%, the number of patients required in each group would be 2135. Table 1 provides sample size estimates for varying effect sizes (rounded to the nearest 5%) and powers of 80% or 90% with a=.05 for both the observed data (approximately 50% of patients demonstrating major improvement) and the upper and lower bounds of the 95%...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Journal of Educational and Behavioral Statistics
سال: 2014
ISSN: 1076-9986,1935-1054
DOI: 10.3102/1076998614523069