Appropriateness of different research designs to different types of question (adapted from Muir Gray21)
| Qualitative research | Surveys | Case control | Cohort | RCT | Systematic review | |
| Effectiveness of an intervention | √√ | √√√ | ||||
| Effectiveness of health service delivery | √ | √ | √ | √ | √√ | √√√ |
| Safety | √ | √ | √√ | √√√ | ||
| Acceptability | √ | √ | √√ | √√√ | ||
| Cost-effectiveness | √√ | √√√ | ||||
| Appropriateness | √ | √ | √√√ | |||
| Quality | √ | √ | √ | √ | √√√ |
RCT, randomised controlled trial.