There are several reasons why the sources show such poor concurrence on asthma. If the mother knows and uses different terms for a health condition than the doctor who told her the child’s diagnosis, she may not identify that condition on the questionnaire For example, asthma may have been referred to by the doctor as “wheezy bronchitis” or “reactive airway disease”, so the mother might not know to mark yes to “asthma” on the questionnaire. This discrepancy could lead to an artifact of non-concurrence even if the reporting sources are referring to the same thing.

Although physicians are trained to distinguish normal speech and language development from that which is truly delayed, most parents are not. For example, in this sample of 3 year-old children, speech problems were reported far more often by mothers than by medical providers. Some mothers may be hyper-vigilant in evaluating their child’s speech and may be over-reporting problems, whereas medical providers may be reporting only clinically meaningful speech problems. On this, and most other health surveys, the mothers’ questionnaire does not offer any definition of the health conditions under study.