= Solution
The chosen <Poisson regression> has fitted mean
$$
\boxed{\widehat\mu(c)=\exp(0.96657+3.02055c).}
$$
For zero building cover, its fitted expected number of floods over the 25-year observation window is $e^{0.96657}\approx2.629$. Increasing the covered proportion by $\Delta$ multiplies the fitted expected count by $e^{3.02055\Delta}$. Thus a ten-percentage-point increase, $\Delta=0.1$, multiplies the expected count by about $1.353$, an increase of $35.3\%$. A one-percentage-point increase multiplies it by about $1.0307$. The full-unit multiplier $e^{3.02055}\approx20.50$ compares proportions differing by one, not percentages differing by one.
These are associations in the <conditional expectation> with the recorded final-year building cover. The <regression coefficient> is not automatically a causal effect of changing development, especially since the count covers 25 years while cover was measured at the end.
Back to article page
