This article provides an applied introduction to Bayesian statistics for so
ciologists. Unlike frequentist statistics, which attaches repeated-sampling
frequencies to test statistics, Bayesian statistics directly describes unc
ertainty about unknown statistical parameters with a probability distributi
on With this foundation, much of Bayesian statistics follows from basic rul
es of probability theory Three areas of Bayesian statistics are especially
relevant for sociologists. First, hierarchical regression models allow seve
ral levels of uncertainty into an analysis. Second Bayes factors provide a
useful approach to the problems of model selection, model averaging, and po
sterior inference about model indexes. Third, recent breakthroughs in estim
ation methods offer valuable new tools for analysis of Bayesian models that
were previously intractable.