Helpful Websites
Atsushi Mizumoto, Professor of Applied Linguistics at Kansai University, has created a very helpful website for using R without having to actually download R or R Commander. The Web App page gives ways to calculate descriptive statistics, statistical tests, appropriate graphics, tests of normality, effect sizes, and confidence intervals for correlation, t-tests, regression, chi-square, non-parametric tests, one-way and two-way ANOVA, cluster analysis, exploratory factor analysis, principal component analysis, correspondence analysis, structural equation modeling, classical test theory item analysis, and IRT models, among others. The user enters their own data and results appear. R code is also available if you want to take the code and modify it yourself. I would have made use of this resource in the book had I been aware of it earlier, but as it is, I heartily recommend it for taking much of the work out of doing statistics in R.
This specific website, within Mizumoto’s “langtest” calculates effect sizes as well as any other online effect size calculator I know and uses summary stats of sample size, mean and standard deviation. In addition, it returns a 95% CI of the mean of the differences, a t-test result, and effect sizes.