Effect sizes and confidence interval

Question 1

two types of effect size estimates?

Answer 1

mean differences & associations

Question 2

What is Cohen’s d?

Answer 2

expresses mean differences in standard deviation units

Question 3

What are the guidelines for Cohen’s d?

Answer 3

.20 = small effect size
.50 = medium effect size
.80 = large effect size

Question 4

What is the difference across versions of d?

Answer 4

Cohen’s d - use when variances are equal, pooled sample SD
Glass’s Δ - uses control group standard deviation in the denominator.
Hedge’s g - superior estimate of standardized mean difference, fades as sample size increases

Question 5

What effect size indicator would you use for an ANOVA and commonly adopted cutoffs?

Answer 5

effect sizes for strength of association, overall main effects and interactions
ω2 – Omega Squared, η2
ω2 , η2 = .01 - small
ω2 , η2 =.06 - medium
ω2 , η2 =.14 - large

Question 6

Difference between point and interval estimates

Answer 6

point estimate - using a single estimate of unknown quantity
interval estimate - using a range of values as your estimate of an unknown quantity
confidence interval - when an interval estimate is accompanied by a specific level of confidence