"… In this little gem of a monograph, Paul Gustafson … argues that partially identified models should not be so quickly dismissed. … Gustafson has drawn together many discussions of identifiability from previous Bayesian analyses (including his own), which are not widely known in non-Bayesian circles. The writing is concise. The examples are simple and insightful. The reader need not be a Bayesian to appreciate this fine monograph."—Dale J. Poirier, University of California, Irvine, in Journal of the American Statistical Association, January 2017