Answer:
longitudinal research design
Step-by-step explanation:
A longitudinal research design or longitudinal survey performs repeated study and observations on a particular group of variables within a short period or long period of time. Data used in this way is called longitudinal data. This is demonstrated in the question above where the researcher Dawn performs observations and studies on a group of children every 6 months for a period of 2 years. Longitudinal research design differs from cross sectional research design that employs fresh data for research periodically for the period of the research