Figure 2

Trace plots of log SMR (= beta) and the estimated logit of proportion of current or former smokers among unexposed to carbon black (= xsm_nexp). Names (beta, xsm_nexp) correspond to the variable names used in the R program (see Additional File 3). Results from an MCMC random walk of length 1,000,000 (Metropolis sampler) in Analysis 1 (CAREX, cohort smoking data). Plots include the burn-in phase of 50,000 cycles to give a complete graphical impression of the convergence behaviour of the Markov chain (Time measures 1,050,000 cycles).