_________ occur when participants improve performance due to subsequent experiences on the same task

What has happened to the poverty rate in the United States since the 1970s?

a. It has steeply declined. b. It has trended downward. c. It has steeply increased. d. It has trended upward.

Randomization in experiments is typically done using

A) a coin. B) an abacus. C) numbers in a hat. D) random numbers.