A METHOD FOR JUDGING ALL CONTRASTS IN THE ANALYSIS OF VARIANCE
A METHOD FOR JUDGING ALL CONTRASTS IN THE ANALYSIS OF VARIANCE
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DOI:
10.1093/biomet/40.1-2.87
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发表时间:
1953-01-01
期刊:
影响因子:
2.7
通讯作者:
SCHEFFE, H
中科院分区:
文献类型:
--
作者:
SCHEFFE, H
A simple answer is found for the following question which has plagued the practice of the analysis of variance: Under the usual assumptions, if the conventional.F-test of the hypothesisH: μ1=μ2=…=μkat the α level of significance rejectsH, what further inferences are valid about the contrasts among the μi(beyond the inference that the values of the contrasts are not all zero)? Suppose theF-test hask−1 andvdegrees of freedom. For anyc1, …,ckwithwrite θ for the contrast, and writeandfor the usual estimates of θ and the variance of. Then for the totality of contrasts, no matter what the true values of the θ's, the probability is 1−α that they all satisfywhere S2is (k−1) times the upper α point of theF-distribution withk−1 andvdegrees of freedom. Suppose we say that the estimated contrast withis ‘significantly different from zero’ if |> S. Then theF-test rejectsHif and only if someare significantly different from zero, and if it does, we can say just which. More generally, the above inequality can be employed for all the contrasts with the obvious frequency interpretation about the proportion of experiments in which all statements are correct. Relations are considered to an earlier method of Tukey using the Studentized range tables and valid in the special case where theiall have the same variance and all pairsi,j(i≠j) have the same covariance. Some results are obtained for the operating characteristic of the new method. The paper is organized so that the reader who wishes to learn the method and avoid the proofs may skip §§ 2 and 5.