Using a real-world setting for an experiment is the hallmark of a(n)

Four-year-old Mary's parents rush into her bedroom when they hear her screaming in the night, but she appears to be sleeping normally when they get there. In the morning, they ask her if she had a bad dream, but she says she didn't. Mary is experiencing

a. sleep terrors. b. nightmares. c. REM sleep behavior disorder. d. hypersomnia.

For which of these would a 2 x 2 table not be a useful cognitive aid?

(a) finding out if gender and aggressiveness in a group of children are related (b) finding out if there is a relationship between IQ and school grades in a group of children (c) finding out how close the relationship is between Johnny and his brother (d) finding out if there is a relationship between population and the crime rate in the 100 largest cities in the US (e) all of the above