Professor Rodgers found that the average level of happiness reported by people under 65 years of age declined from 1957 to 1970.
However, for this same group, the average level of happiness increased slightly from 1970 to 1978. Rodgers also found that the average level of happiness reported by people age 65 and older increased from 1957 to 1978. A(the) variable(s) in this study is(are):
Independent variable: In a psychological or scientific experiment, the term independent variable is defined as the variable that is being manipulated or controlled or changed during an experiment by the experimenter.
In an experiment, the experimenter changes or manipulates the independent variable to see its effects on the dependent variable, i.e, any changes in the independent variable will cause changes or alteration in the dependent variable.
In the question above, the independent variable is Age.
