A researcher is concerned that gender may affect how subjects respond to an experimental stimulus. So subjects are paired with another subject who has the same gender, and one member from each pair is assigned by a flip of a coin to the experimental group and one to the control group. This method of assigning subjects to groups is called:

The answer is "Matching"

Explanation:

Matched groups method refers to research- technique, in which the experimental community participant. It is subjected to modification, that is contrasted to a specific participant in the control group on an outcome measure, that is different in some important manner but not controlled.

i don't get what you mean

explanation:

answer; ethnocentric;