Effective degrees of freedom and the likelihood ratio test
有效自由度与似然比检验
Normal-theory problems involving several unknown variances may require use of estimates not having simple chi-squared distributions. Confidence intervals are then commonly based on the use of ‘effective degrees of freedom’, i.e. the fitting of a gamma distribution via the first two moments, replacing parameters by estimates. The confidence intervals given by this method are compared with those resulting from the likelihood ratio test, inserting a Bartlett adjustment factor…