Recall Bias
Recall bias is bias caused by inaccurate or incomplete recollection of events by the respondent. It is a particular concern for retrospective survey questions.
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Guidelines
How long is "too long" for recall?
It depends on the type of event respondents are being asked to recall. Research shows strong evidence of recall bias in food consumption, but little evidence for agricultural production. As a rule of thumb, infrequent events (e.g. purchases of major assets) will be memorable for longer periods of time than routine events (e.g. use of public transportation).
How to avoid recall bias?
Useful strategies:
- Reduce recall periods as much as possible. For example, add follow-up surveys by phone, or personal diaries.
- Conduct focus groups to understand salience of the indicator in question, and gauge a reasonable recall period.
- When Piloting your Survey, carefully test recall periods; if possible try shorter and longer periods and check for differences in variance
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This article is part of the topic Questionnaire Design
Additional Resources
- DIME Analytics (World Bank), Survey Instrument Design and Pilot
- IFPRI, Measuring anchoring bias in recall data
- Jed Friedman (World Bank), Response Error in Consumption Surveys, and the related paper
- Financial Access Initiative, The Reliability of Self-reported Data
- Jishnu Das, Jeffrey Hammer, Carolina Sánchez-Paramo, The impact of recall periods on reported morbidity and health seeking behavior
- Kathleen Beegle, Calogero Carletto, Kristen Himelein, Reliability of recall in agricultural data
- Philip Wollburg, Marco Tiberti and Alberto Zezza, Recall length and measurement error in agricultural surveys