Roberts, I.

effect treatment treatment effect trial covariate adjustment covariate centre difference study adjustment sample size injury model crash between-centre differences outcome brain injury power sample analysis regression between-centre impact treatment effects reference mortality brain population reference analysis individual patient 14- day mortality corticosteroid pupil pupil reactivity prognostic strategy ficient range characteristic score coef ficient reactivity randomized result level measure heterogeneity study population country group ratio table crash trial murray gd design 14 day mortality steyerberg ew baseline / journal odds ratio baseline characteristics selection steyerberg placebo intercept health signi analyses head injury regression coef ficient example risk model butcher i z-score impact study group reduction 14- alternative strategy β1 xij