OTTAWA - Research has already found that Canadians think they're skinnier and taller than they really are, but a new study suggests they're also off the mark when it comes to the height and weight of their kids.

The Statistics Canada research suggests rates of childhood obesity in the country are inaccurate as they most often rely on data from parents.

A determination of obesity is based on a height-to-weight ratio, so when one of the data sets is wrong, it can skew the results.

The study found that on average, parents underestimated their child's height by 3.3 centimetres and weight by 2.4 pounds.

It also found that many children whose weight was under-reported were in fact obese, while those who height was under-reported were erroneously classified as being obese.