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

Pratap Kumar Jena,G Jahnavi,Jugal Kishore

doi:10.7314/apjcp.2013.14.6.3865

Abstract

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. 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. 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.

Highlights

Digit bias has been widely discussed in tobacco epidemiological survey for self-reporting of cigarette per day (CPD) frequency (Means et al, 1992; Klesges et al, 1995; IARC, 2008)
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
Digit bias has been widely discussed in tobacco epidemiological survey for self-reporting of cigarette per day (CPD) frequency (Means et al, 1992; Klesges et al, 1995; IARC, 2008)

Summary

Introduction

Digit bias has been widely discussed in tobacco epidemiological survey for self-reporting of cigarette per day (CPD) frequency (Means et al, 1992; Klesges et al, 1995; IARC, 2008). Surveys are valid ways to estimate tobacco use prevalence (Caraballo et al, 2001; 2004) but the accuracy of CPD data may suffer from digit bias like reporting of excess frequencies at round or preferred figures (Klesges et al, 1995; IARC, 2008). 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. Adapted Whipple Index was estimated to assess digit bias and data quality of reported CPD frequency. Exploring alternative methods to reduce digit bias in cross sectional surveys should be given priority

Objectives

Methods

Results

Conclusion