I am reading Hosmer's Applied Logistic Regression, and I am a bit stuck in chapter 3, when taking about interaction and confounders.
In page 77, it states the following:
Using the estimated coefficient for LWD in model 1 we estimate the odds ratio as $\exp(1.054)=2.87$. The results shown in Table 3.14 indicate that AGE is not a strong confounder, $\Delta(\hat{\beta})\%=4.2$, but it does interact with LWD, $p=0.076$.
I am OK with the $\exp(1.054)=2.87$, but I can't figure out how he calculate the $\Delta(\hat{\beta})\%=4.2$.
Can anyone help? Thanks.