Calcium supplementation was independently associated with mortality after adjusting for confounding variables.这句话中，Calcium supplementation是要研究的自变量，mortality是因变量。在做回归分析时还纳入了不少其他混杂因素，比如性别、年龄、血压等等。那么请问， adjusting for confounding variables这句话是什么意思呢？是说控制其他混杂因素不变么？R中如何做到呢？文献中看到很多类似adjustment/adjusted for other variables之类的话，这到底是什么意思呢？