A researcher is running a study to determine how employees of a certain company commute to work. In order to complete the study, the researcher selects a sample of 300 employees of this company and records their means of arrival on a specified day.
If the researcher also wants to consider the age of the employee as an additional factor in this study, what would this be considered?
a) Matching
b) Placebo Effect
c) Blocking
d) Stratifying
e) Control