A good design is one that rules out explanations of the results other than the effect of the independent variable
分析a good design is a design
.the design rules out explanations of the results ,
the design does not rule out the effect of the indepedent variable
然后,你把以上三句再翻译一下,就ok了
翻译：好的设计不看结果的解释,只注重变量的效果.