| Type |
Examples |
| Systematic Review |
Summary of results of all relevant trials |
| Meta-Analysis |
Summary of average results of trials. |
| Randomized Controlled Trial |
Isolation of effect. All other differences are random and thus statistically controllable. |
| Cohort Study |
For example number of cortisone inhaler prescriptions before and after high speed films could be introduced, or number of patients referred to speech therapy based on voice diagnosis. |
| Case-Control Study |
Looking at patients with a certain disease and patients matching these patients except for the disease. |
| Cross-sectional Survey |
Looking at a representative sample here and now: How many took medication A and did not have disease B. |
| Case report |
Description of individuals: A patient took medication A and it cured disease B (but no proof what caused, disease B to be cured). |
