Final answer:
Frequency matching is a method used in experimental design to pair each control with a case that has similar values for specific variables, helping reduce confounding effects and ensuring the study focuses on the cause-and-effect relationship between the independent and dependent variables.
Step-by-step explanation:
Frequency matching in research refers to a strategy used in experimental design to ensure that the control group mirrors the experimental group in terms of specific variables, or matching variables. This technique helps in eliminating the confounding effects of these variables, hence allowing the researcher to observe the impact of the independent variable on the dependent variable more clearly. In frequency matching, each control is paired with a case that has similar values for the variables that are being matched. These matching variables might include demographic factors like age, socioeconomic status, or other specific characteristics relevant to the study.
To implement frequency matching, subjects must be assigned to their respective groups with consideration of these matching variables. This method differs from random assignment, where participants have an equal chance of being assigned to either the experimental or control groups, but matching specific characteristics is not guaranteed. However, when correctly applied, both methods aim to reduce bias and ensure that any measured effects on the dependent variable are directly attributable to the manipulation of the independent variable, thus affirming a cause-and-effect relationship in the study.