Nor does an increase in calorific intake provide a simple explanation.

Only if the same association is shown by others and defies simple explanation should it be taken seriously.

The simplest explanation would be that anxious men tend to smoke and drink more and look after themselves less.

There is not a single, simple explanation for this abject failure, but a series of overlapping factors.

The simplest explanation of why jobs are growing without output is that productivity is very low.