Problem: Dr. Wide is conducting a literature review to determine how much evidence there is that sleep deprivation causes memory loss. First, she identifies which studies are correlational. From the set of questions below, which one would allow her to determine whether or not the study is "correlational?"
A) Are the measures of sleep and memory reliable?
B) Are both sleep and memory measured (not manipulated)?
C) Is the relationship between sleep and memory graphed as a scatterplot or a bar-graph?
D) Is an r-value used as one of the statistics to report the relationship between sleep and memory?