Recently several criteria have been proposed for selection of orders of AR models. One of these, namely the AIC has been used in hydrologic analysis. However, the results given by these criteria when observed hydrologic data are analyzed by using them have not been studied to determine the variability in the results obtained by these criteria.

Some of the more widely discussed of these criteria have been analyzed in this paper by using both hydrologic and nonhydrologic time series. The orders of AR models given by Akaike's information criterion, the final prediction error criterion, the criterion autoregression transfer function, Schwarz's criterion and the posterior probability criterion have been analyzed, and the results are discussed.

Although the results obtained by these criteria are often similar, the posterior probability criterion has been recommended for use because it is possible to estimate the probability of the order being correct by using it.