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1·Psychologist Nina Strohminger at the University of Pennsylvania, who was not involved in the study, says she wants the effect to be real but cannot rule out some unknown confounding variable.

没有参与这项研究的宾夕法尼亚大学心理学家尼娜·施特罗明格指出，她希望这种影响是真实的，但不能排除一些未知的混杂变量。

2·As far as skulls are concerned, there is one confounding variable: climate.

至于说到头骨，这里有个容易混淆的变化因素：气候。

3·If that confounding variable can be taken care of, though, and the effect persists, the next obvious step is to determine what mechanism within the mother's body causes the discrepancy.

假设在排除这些变量因素的条件下(如果这些变量真的存在)，上述结果仍然生效，那么下一步就需要研究到底是母亲身体里的什么机制决定了子女的性别差异。

4·Further, the absolute concentrations of these metabolites in EPS appear to be independent of age, increasing the potential utility of these markers due to elimination of age as a confounding variable.

另外，EPS中这三种代谢物的绝对浓度看起来与年龄无关的。由于不需要年龄作为混杂变量，增加了这些标记物的潜在效用。