How Many Cigarettes Did You Smoke? Assessing Cigarette Consumption by Global Report, Time-Line Follow-Back, and Ecological Momentary Assessment

Objective: This study evaluated and compared several methods of assessing daily cigarette consumption. Design: Comparison of measures of daily cigarette consumption from several sources, from 232 smokers entering a smoking cessation program. Main Outcome Measures: Global reports of average smoking, Time-Line Follow-Back (TLFB) recall for the week preceding the study (premonitoring TLFB), 2 weeks' cigarette recordings using electronic diaries and ecological momentary assessment (EMA), and TLFB recall of smoking during EMA (monitored TLFB). Results: Global reports and premonitoring TLFB showed severe digit bias: six times as many values as expected were rounded at 10. Monitored TLFB also showed substantial digit bias (four times). EMA data showed none. EMA averaged 2.6 cigarettes lower than monitored TLFB, but exceeded TLFB on 32% of days. Across days, EMA and TLFB only correlated 0.29. Daily variations in TLFB did not correlate with variations in carbon monoxide (CO) measures taken on 3 days, but EMA measures did; among participants whose CO varied, r = .69. CO correlated with EMA cigarettes recorded in the preceding 2 hours, suggesting timely recording of cigarettes. Conclusion: TLFB; measures are limited for precise assessment of cigarette consumption. EMA measures appear to be useful for tracking smoking, and likely other health-relevant events.