Reporting by parents of longstanding illness in their adolescent children.

Parents' proxy reports of longstanding illness in their 15 year children are compared with the young people's own reports, both overall and between different reporting contexts; mother alone, father alone and both parents together. Parents over-report longstanding, but not limiting longstanding, illness in comparison to self report. There is no evidence of differential over-reporting by reporting context, but a number of differences are found in the likelihood of disagreement between these reporting contexts. The gender of the young person influences the relationship between proxy and self reports.