We have seen no problematic or consistent source of bias through using large scale access panels, other than they tend to under-represent the eldest age groups (at the moment). We invite you to compare our sample to other sources of comparison on the profile of your category. Because we only allow in people who have recently bought your category it has always proven to be a similar profile to that which clients expect, although one might expect a slight bias to more frequent shoppers since we recruit based on shopped in the last few days. Our programs are the largest surveys operating in the world today. Their sheer scale means they are the most representative data source of its kind.