Samenvatting
Two types of experimental strategies are presented together with applications to accident research. Type 1 experiments aim towards direct control of causal variables with the ambition of establishing demonstrable cause and effect relationship. Type 2 experiments are planned to establish statistical association between effects and possible causal variables, but executed to make cause and effect relationships strongly plausible. The need for an array of major, professionally managed, reliably funded, accident research institutes or laboratories is emphasized.