  Gamma-Ray Bursts (GRBs) have been conventionally bifurcated into two distinct
categories dubbed "short" and "long", depending on whether their durations are
less than or greater than two seconds respectively. However, many authors have
pointed to the existence of a third class of GRBs with mean durations
intermediate between the short and long GRBs. Here, we apply multiple model
comparison techniques to verify these claims. For each category, we obtain the
best-fit parameters by maximizing a likelihood function based on a weighted
superposition of lognormal distributions. We then do model-comparison between
each of these hypotheses by comparing the chi-square probabilities, Akaike
Information criterion (AIC), and Bayesian Information criterion (BIC). We
uniformly apply these techniques to GRBs from Swift (both observer and
intrinsic frame), BATSE, BeppoSAX, and Fermi-GBM. We find that the Swift GRB
distributions (in the observer frame) show evidence for three categories at
about $2.4\sigma$ from difference in chi-squares and show decisive evidence in
favor of the two components using both AIC and BIC. For all the other datasets,
evidence for three components is either very marginal or not favored.
