On distribution of AIC in linear regression models

This paper investigates an asymptotic distribution of the Akaike information criterion (AIC) and presents its characteristics in normal linear regression models. The bias correction of the AIC has been studied. It may be noted that the bias is only the mean, i.e., the first moment. Higher moments are important for investigating the behavior of the AIC. The variance increases as the number of explanatory variables increases. The skewness and kurtosis imply a favorable accuracy of the normal approximation. An asymptotic expansion of the distribution function of a standardized AIC is also derived.