Since tT was also obtained by fixed-effects regression, the variance of this estimate is available from standard regression theory and is reported in Table 3. However, the sampling distributions of the other variance components estimators are not known and, even under normality assumptions, usable expression for the variances of the estimates are not available. To provide some guidance on this matter I provide standard errors of the estimates that would be observed were the true variance components equal to their estimated values and were the underlying distributions normal. These estimates were obtained by simulation: taking the variance components at their estimated values, a realization of each effect in the model was generated by a draw from the appropriate normal distribution, these effects were then combined according to the original data structure, and the variance components estimation procedure was then reapplied to the simulated data set. The standard errors shown are based on 1000 such trials. The values obtained offer convincing evidence that the estimates of the larger variance components are not overly noisy. With regard to the corporate effects, I conclude that there is no evidence of non-zero corporate effects in sample A, whereas the inclusion of the smaller business-units (sampleB) provides some evidence of (small) corporate effects.