Implications of chance baseline differences in repeated measurement designs.
Implications of chance baseline differences in repeated measurement designs.
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DOI：
10.1080/10543409408835083
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发表时间：
1994-07-01
影响因子：
1.1
通讯作者：
Doyle, S R
中科院分区：
文献类型：
--
作者：
Overall, J E;Doyle, S R
通过重复测量ANOVA和线性趋势分析（基线值和基线值不存在协变）分析代表随机化、平行组设计的数据集。组间主效应、组X次交互作用和各时间段线性趋势差异的ANOVA检验显示为严重保守或严重非保守，具体取决于随机基线平均差异的方向和显著性。在重复测量ANOVA中纳入基线评分作为协变量，可适当校正随时间推移的组间（平均值）效应，但协变量未校正受试者内效应，受试者内效应与随时间推移的变化率或模式差异有关。如果希望评价治疗诱导变化模式之间的差异，建议对基线协方差校正的复合趋势评分进行组平均值差异的显著性检验。如果没有或不能使用协方差校正，则需要明确识别随机基线差异对显著性检验的潜在“有利”或“不利”影响。
Datasets representing randomized, parallel-groups designs were analyzed by repeated measurements ANOVA and linear trend analysis with and without baseline values being covaried. ANOVA tests for the between-groups main effect, groups X times interaction, and differences in linear trends across time periods are shown to be seriously conservative or seriously nonconservative, depending on the direction and significance of chance baseline mean difference. Inclusion of baseline scores as a covariate in the repeated measurements ANOVA provides appropriate correction for the between-groups (average) effect across time, but the covariate provides no correction for the within-subject effects that are concerned with differences in the rates or patterns of change across time. If one desires to evaluate differences between patterns of treatment-induced change, tests of significance for differences in group means on composite trend scores with covariance correction for baseline are recommended. If covariance correction is not or cannot be employed, the potentially "favorable" or "unfavorable" influence of chance baseline differences on tests of significance needs to be explicitly recognized.