Two-sample MR in which IPD is available. NOTE: some MR studies use a mixture of aggregate and IPD (where the genetic IV–risk factor association may be from aggregate data and the genetic IV–outcome association may be from IPD – or vice versa).
Assumptions and key sources of bias are as for two-sample MR. There is more potential (than with aggregate data) for assessing the genetic IV association with observed confounders of the risk factor-outcome association, exploring interactions or subgroup effects and removing overlapping samples.


References
- Davey Smith G, Hemani G. Mendelian randomization: genetic anchors for causal inference in epidemiological studies. Hum Mol Genet 2014;23:R89-R98.
- Lawlor DA. Two-sample Mendelian randomization: opportunities and challenges. . International Journal of Epidemiology 2016;doi:10.1093/ije/dyw127.
Other terms in 'Definition of MR and study designs':
- Bidirectional MR
- Binary exposure MR
- Factorial MR
- Instrumental variable (IV)
- Mendelian randomization (MR)
- Multivariable MR
- One-sample MR
- Two-sample MR
- Two-sample MR with summary (aggregate) data
- Two-step/Mediation MR