Problem
1. Explain why the differences-of-means estimator, applied to data from a randomized controlled experiment, is an estimator of the treatment effect.
2. Sketch a hypothetical scatterplot for a sample of size 10 for two random variables with a population correlation of (a) 1.0; (b) -1.0; (c) 0.9; (d) -0.5; (e) 0.0.
The response should include a reference list. Double-space, using Times New Roman 12 pnt font, one-inch margins, and APA style of writing and citations.