Sample sizes, scoops and educational science

Sample Sizes for Multilevel Modeling

Sample Sizes To Estimate Proportions And Correlation

Very often statisticians have to deal with the problem of sample size calculation. However this is one of the most difficult questions to be answered since it depends on many considerations, assumptions and restrictions on the real problem being solved. In this paper we develop some methods, based on credible intervals, to calculate sample sizes for proportions and correlations.

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...

Exploratory 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...

Sample 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%...