Questionnaires and control groups

If 25% of people with Crohn's disease don't like berry fruit, is that significant? To identify foods likely to be involved, it is important to collect information about the dietary preferences of people without Crohn's disease as well. Lynn Ferguson, programme leader for New Zealand, explains why.

Transcript

Professor Lynn Ferguson ( )

We think it’s quite important to get a sense of what proportion of the population won’t eat that food stuff anyhow. So it might be that 25% of our Crohn’s patients don’t want to eat berry fruit, but then we go to our control population and find that 20-25% of people don’t like eating berry fruit because it doesn’t make them feel any good, anyhow.

So we might have something there that we thought was specific, something genetic about Crohn’s patients, but it’s actually something that’s typical of the rest of the population too. So it a good idea to go out and check if other people have got the same distribution of likes and dislikes, or feelings that things [foods] make them better or worse.