Development and validation of a scale measuring self-efficacy of current and former smokers

Abstract

Aims: To develop and test the validity of a questionnaire measuring the confidence of current and former smokers in their ability to abstain from smoking in high-risk situations.

Design and participants: We collected qualitative data in a first mail survey in 115 smokers and ex-smokers, and used these data to develop survey items. We collected quantitative data in a second mail survey in 529 smokers and ex-smokers to finalize the instrument.

Setting: General population in Geneva, Switzerland, 1995, 1997 and 1998.

Findings: The study resulted in a two-dimensional 12-item scale: the "Smoking Self-Efficacy Questionnaire" (SEQ-12). The two six-item subscales measure confidence in ability to refrain from smoking when facing internal stimuli (e.g. feeling depressed) and external stimuli (e.g. being with smokers). Internal consistency coefficients were high ("internal stimuli": alpha = 0.95; "external stimuli": alpha = 0.94). Test-retest intraclass correlation coefficients were high (0.95 and 0.93 for the two scales, respectively). In smokers, baseline self-efficacy scores predicted smoking cessation at 16-month follow-up. Finally, the scale respected criteria of content- and construct validity.

Conclusion: SEQ-12 is a valid and reliable scale, which has applications in both research and clinical settings. It can also produce input data for computer systems that generate counselling reports tailored to the characteristics of each individual smoker.