TY  - GEN
AU  - Gray-Donald,K
AU  - Kramer,M S
TI  - Causality inference in observational vs. experimental studies. An empirical comparison
SN  - 0002-9262
PY  - 1988///0518
KW  - Epidemiologic Methods
KW  - Humans
KW  - Random Allocation
N1  - Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Review
UR  - https://doi.org/10.1093/oxfordjournals.aje.a114891
ER  -