Dr. Mottle is using stratified sampling and has two frames. If she needs 11% from a frame of 200 and 89% from a frame of 1000, what is the total sample size?

Which confounding variables cannot be completely controlled because of ethical constraints on the research?

A) maturation and history B) maturation, selection, and regression to the mean C) attrition and selection D) regression to the mean and instrumentation

Describe the branches of Mexico's government and the changes they have undergone

Indicate whether this statement is true or false.