Past exam of the systems biology course of the University of Cambridge / 2024 / Paper 3 / 1 / d / Solution

At a conventional 5% significance level, there is evidence for an association with sex after adjusting for weight, because its two-sided p-value is $0.00131<0.05$. There is insufficient evidence for a weight association after adjusting for sex, because its p-value is $0.62392>0.05$.

These Student t-tests test whether the corresponding regression coefficients are zero within the additive multiple linear regression. Failure to reject the weight hypothesis does not establish an exactly zero effect; these associations alone also do not justify a causal inference. The later model with a statistical interaction asks a different question, allowing the weight association to differ by sex.