Correlates of Digit Bias in Self-reporting of Cigarette per Day (CPD) Frequency: Results from Global Adult Tobacco Survey (GATS), India and its Implications

Abstract

Background: Cigarette per day (CPD) use is a key smoking behaviour indicator. It reflects smoking intensity which is directly proportional to the occurrence of tobacco induced cancers. Self reported CPD assessment in surveys may suffer from digit bias and under reporting. Estimates from such surveys could influence the policy decision for tobacco control efforts. In this context, this study aimed at identifying underlying factors of digit bias and its implications for Global Adult Tobacco Surveillance. Materials or Methods: Daily manufactured cigarette users CPD frequencies from Global Adult Tobacco Survey (GATS) -India data were analyzed. Adapted Whipple Index was estimated to assess digit bias and data quality of reported CPD frequency. Digit bias was quantified by considering reporting of '0' or '5' as the terminal digits in the CPD frequency. The factors influencing it were identified by bivariate and logistic regression analysis. Results: The mean and mode of CPD frequency was 6.7 and 10 respectively. Around 14.5%, 15.1% and 15.2% of daily smokers had reported their CPD frequency as 2, 5 and 10 respectively. Modified Whipple index was estimated to be 226.3 indicating poor data quality. Digit bias was observed in 38% of the daily smokers. Heavy smoking, urban residence, North, South, North-East region of India, less than primary, secondary or higher educated and fourth asset index quintile group were significantly associated with digit bias. Discussion: The present study highlighted poor quality of CPD frequency data in the GATS-India survey and need for its improvement. Modeling of digit preference and smoothing of the CPD frequency data is required to improve quality of data. Marketing of 10 cigarette sticks per pack may influence CPD frequency reporting, but this needs further examination. Exploring alternative methods to reduce digit bias in cross sectional surveys should be given priority

Is individual smoking behaviour influenced by area-level ethnic density? A cross-sectional electronic health database study of inner south-east London

“…Second, the use of cigarettes smoked per day as a measure of smoking intensity may be unreliable. Self-report of cigarettes smoked per day is prone to digit bias (rounding to multiples of 10 due to standard pack-sizes) and under-reporting [39]. Under-reporting may be particularly prevalent among high-intensity smokers due to social desirability bias.…”

Comparison of Biomarkers of Tobacco Exposure between Premium and Discount Brand Cigarette Smokers in the NHANES 2011–2012 Special Sample

“…While self-reported measures of cigarettes per day (CPD) and when the participants smoked their last cigarette are relatively standard questionnaire items, they are flawed as proxies for measuring dose exposure. These types of self-reported responses are commonly subject to imprecision and systematic errors, such as digit and recall bias (51). Instead, serum cotinine was used as a more accurate physiological measure of recent nicotine exposure, as opposed to reliance on survey self-report.…”

Data Quality of Select Economic Indicators in a National Survey Using Handheld Device: Experience from Global Adult Tobacco Survey, India (2009-2010)

“…Jena et al [17] further elaborated the concept of interaction between different nicotine containing tobacco products that have led to Simpson's Paradox . Apart from these, high digit bias (modified Whipple Index -226.3) while collecting information on the quantity of cigarette used per day among daily users, which further reconfirms poor data quality in GATS-India survey [15]. The authors have also identified the imprecise definition of 'current daily user' and 'current less than daily use' resulting in more than one-fifth invalid responses regarding 'the duration of last quit attempt' among current tobacco users as well as up to 10% invalid responses regarding duration of abstinence [16].…”

“…However a study by Giovino et al [12] on 14 countries GATS data, indicated a peculiar anomaly suggesting female daily smokers use more number of cigarettes per day than their male counterparts in India (not in other 13 countries) only. This anomaly was questioned in the pretext of poor data quality and other issues in various studies [13][14][15][16][17]. This study is further expanded to examine data quality while assessing economic indicators of tobacco use (last purchase and price paid for it) from items F01 and F02 of GATS-India survey tool.…”