Twenty sets of depressed twins are obtained for a study on the effects of a new antidepressant. In each twin set, one twin is assigned to receive the drug, and the other is designed to receive the placebo. Three months later, depression levels are measured on a scale from 1 (not at all depressed) to 7 (very depressed). The following data were obtained:
GROUP 1 = Received drug
GROUP 2 = Received placebo
Variable = Depression level
GROUP N Mean SD
GROUP 1 10 3.21 1.035
GROUP 2 10 5.77 1.772
t = 5.785 df = 9 p = 0.017 Cohen’s d = .88
What is the independent variable?
What is the dependent variable?
What is the scale of measurement for the dependent variable?
What kind of research design was used?
What kind of statistical analysis was used?
Is the effect size small, medium, or large? How do you know?
( this site will help with apa format: https://owl.english.purdue.edu/owl/section/2/10/ )