===== Research designs =====
{{topic>correlational_research cross-sectional_research longitudinal_research cohort_study panel_study natural_experiment quasi_experiment interrupted_time_series_design classical_experiment experiment experimental_group control_group double-blind_experiment random_assignment matching posttest pretest treatment observation placebo +research_methods:video}}

===== Assignments =====

{{topic>correlational_research cross-sectional_research longitudinal_research cohort_study panel_study natural_experiment quasi_experiment interrupted_time_series_design classical_experiment experiment experimental_group control_group double-blind_experiment random_assignment matching posttest pretest treatment observation placebo +research_methods:assignment}}