# Estimating Magnitude of Effect

 What is R2? The variability accounted for by the full modelThe sum of squares for the model divided by the SS total How might one express the magnitude of effect? 1) Find the R22) Express the difference in means and SD How might one express the difference between the means and SD of two data sets The means must be compared in SD units Cohen's D is employed What is the formula for independent group Cohen's D? Mean 1- mean 2 divided by the standard deviation of the scores (or residuals) How can we estimate d values? If population means or SD are not known we replace the parameter values with their corresponding statistics What is a small effect size? 0.20 What is a medium effect size? 0.50 What is a large effect size? 0.80 What is the d value used for? As a descriptive statistic (provides an index that can be used to compare effect sizes across different experiments)Deciding upon sample sizes Estimating power What is experimental precision? The amount of variability in true parameter estimatesThe less variability, the greater the precision How can we increase experimental precision? Reduce the size of standard error The best way of doing this is to increase sample size Authorcamturnbull ID297015 Card SetEstimating Magnitude of Effect Description. Updated2015-02-27T14:02:35Z Show Answers