Question: what are the different types of research study designs?
Answer: Meta-Analysis. A way of combining data from many different research studies. ... 
Systematic Review. ... 
Randomized Controlled Trial. ... 
Cohort Study (Prospective Observational Study) ... 
Case-control Study. ... 
Cross-sectional study. ... 
Case Reports and Series. ... 
Ideas, Editorials, Opinions.