Epidemiology and Infection
- Epidemiology and Infection / Volume 138 / Issue 02 / February 2010, pp 264-269
- Copyright © Cambridge University Press 2009
- DOI: http://dx.doi.org/10.1017/S0950268809990422 (About DOI), Published online: 05 August 2009
Original Papers
Recall errors in a weekly survey of diarrhoea in Guatemala: determining the optimal length of recall
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SUMMARY
We measured the recall error, optimal recall length and factors associated with diarrhoea in a weekly survey. Data was taken from a year-long randomized controlled trial in which characteristics of diarrhoeal episodes were recorded weekly. We labelled the recall period as days 1–6; day 1 being the day before the visit. Recall error was the percentage difference between the number of episodes reported to begin on a particular day and the mean for days 1 and 2. Generalized estimating equations were used to determine associations. Recall error was 37% on day 3 and 51% on day 5. The error was less in younger children (by 10%), severe episodes (by 29%) and when blood was present in the stool (by 18%). Diarrhoea was underreported when the recall period extended beyond 2 days. Surveys that use longer recall periods risk underestimating diarrhoea incidence and selectively capturing more severe episodes.
(Accepted June 29 2009)
(Online publication August 05 2009)
Key Words:Bias; diarrhoea; recall; survey
Correspondence:
c1 Author for correspondence: Dr S. N. Zafar, M-79 Khayaban-e-Ittehad Phase 7 DHA, Karachi, Pakistan. (Email: zafar.nabeel@gmail.com)
