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of α ( . 10 , . 05 and . 01 ) and various combinations of parameters n , m , p and q . Each combination was replicated 10,000 times. We compared only two estimators this time: the least-squares estimator and the 10% metrically trimmed GMt estimator with ν = 5 . We see in Table 2 that the asymptotic χ 2 pq approximation works reasonably well for the least- squares estimator if the ratio n/pq exceeds 15; however, for the GMt estimator a ratio n/pq of at least 35 is necessary for the asymptotic approximation to be reasonably good. Therefore, the asymptotic Wald test can be used with confiden ce only for large sample sizes and relatively small dimensions. In other cases, permutation tests or Wald tests with bootstrap-estimated covariances are preferable. 

