all variables with a  possibility of less than p= 0.5 in X square texts of being  equally  distributed in the open and laprascopic surgery groups are regarded as potential confounders which must be adjusted for . 请问 这句里 being equally distributed 怎么解释？是在开腹和腹腔镜手术两组中，卡方检验中P值小于0.5的变量，且这些变量在两组中均匀分布吗？ 这句话怎么解释 求赐教 感谢