OBJECTIVE To improve the quality and utility of orthogonal experiments.METHODS The orthogonal experiments in published literatures were reviewed.RESULTS The common mistakes made in some literatures and outcomes were: orthogonal design or orthogonal table without blank column,resulting in inflating the random effect;baselessly ignoring the interactions,resulting in confounding bias;wrong results of analysis of variance(ANOVA) because of manual calculation;the selection of optimal process without considering ...