Final answer:
Meta-analysis is the method not used in developmental psychology from the list given. The other methods—case study, longitudinal study, and observational study—are indeed used in this field.
Step-by-step explanation:
The research method used in developmental psychology that is not listed in the choices provided is meta-analysis. A case study, a longitudinal study, and an observational study are indeed common research methods in developmental psychology. Specifically:
- A case study is a deep dive into a single case, often over a long period.
- A longitudinal study tracks participants over a lengthy period of time.
- An observational study involves watching and recording behaviors as they occur.
On the other hand, a meta-analysis is a statistical approach that combines the results of multiple studies addressing a set of related research hypotheses.