Researchers found that attitudes regarding alcohol were somewhat different for 12-year-olds, 15-year- olds, and 17-year-olds. all measures were taken during the same year from children of different ages. this type of research is an example of the research method

This type of research is an example of the research method called cross-sectional research.

Explanation:

Cross-sectional research is a research design or method used in observational studies. The reseracher measures the dependent variable in different population groups at the same point in time. The population groups or cohorts are chosen depending on the research question, they can be based on age (like in the example in the question), gender or race, among other categories. Usually the outcomes are compared to one another.