Schultz et al (1980) assessed the intelligence of 100 young and 100 older people (average age was about 20 years and 64 years respectiv ely). They found declines in certain kinds of intelligence and spontaneous flexibility with age. (a) Identify the independent and dependent variables in this study. (b) Did they use a longitudinal or crosssectional design? Briefly explain your answer.

a. Independent - age; Dependent - intelligence

b. Cross-sectional

Explanation:

Scientific experiments label the variables that they employ in two ways: dependent and independent. Independent variables are those that are changed or manipulated by the researchers. In this case, the researchers are exercising control over the variable of age by selecting a particular type of people. This also means that the researchers believe this variable to have a direct effect on the dependent variable.

On the other hand, dependent variable refers to the variable being tested and measured. It receives this name because the variable is "dependent" on the independent variable. In this case, intelligence is the variable that is believed to depend on age.

Finally, this is also an example of a cross-sectional study. Cross-sectional studies interview different samples of people at a particular point in time. This allows us to have a snapshot of a group at a particular moment. This is different from longitudinal studies, which follow the same sample of people over a long period of time.