Accuracy of answers obtained using a one-year recall period compared to a series of fortnightly recalls.
In a study to examine factors influencing transmission of hepatitis B virus, a comparison has been made between answers obtained about events occurring over a one-year period and the summation of the results from fortnightly questionnaires administered over the same period. Complete data were available for 532 children and the results showed that for an estimate of rates within the population, the results from both methods were similar. At the individual level, however, the differences between the one-year recall and fortnightly questions were large. Thus it appears that for population estimates longer recall periods may be satisfactory, but in any study requiring accurate data at the individual level shorter recall periods are required.
Child, Preschool↗