Researchers studied frequency and amount of alcohol use in three groups of students (grades 6 to 8, grades 9 to 10, and grades 11 to 12) over five years. With this
\_\_\_\_\_\_\_\_ researchers can examine age-related changes and changes within the same individuals as they age. In addition, researchers can account for the possibility of
cohort and/or time of measurement effects.
a. longitudinal research design
b. cross-sectional research design
c. observational research design
d. sequential research design