"I need a epidemiology with definition." "And tools of measurement, maaah." Standardization observational studies. Like descriptive, unclinical studies, cross-sectional, case control, cohort, to ecological studies. An odds ratio, risk ratio, attributional ratio, population risk ratio, experimental and intervention studies, classification like randomization, evidence-based medicine. All with examples. And errors in epidemiology. I need clear-cut explanation. And examples which, uh, even normal people can understand. Thank you. Give me the answer first.