Truthful Response
From ICE Primer: A Tobacco Control Research Methodology Primer
One of the challenges in the collection of data on smoking habits is developing procedures that will lead to truthful response, either about whether an individual is a smoker, or the amount an individual smokes. There are several methods used in tobacco control studies to increase the likelihood of truthful response, or, at the least, to detect when a response may not be truthful.
These methods include:
- assuring confidentiality. For example, in studies in schools, using data collectors from outside the school, using questionnaires without names attached, and allowing students to seal their questionnaires in plain envelopes before handing them in are all methods to promote the idea that it will not be possible to link the questionnaire to the student.
- biochemical validation. Analyzing breath, saliva, urine or hair samples from participants for markers such as carbon monoxide (breath samples), or thiocyanate or cotinene (saliva or urine samples) can allow for a check on whether an individual has smoked recently.
- bogus pipeline. With the bogus pipeline procedure in tobacco control studies, breath or saliva samples are collected from subjects but not analyzed. The act of collecting the samples is designed to promote a truthful response.
While biochemical validation is the gold standard to have confidence in a subject's responses, there are difficulties with each of the biochemical markers. Carbon monoxide is non-invasive and simple and inexpensive to collect in the field. However, it has a relatively short half-life and so can indicate only recent exposure. It also is found in second hand smoke, in automobile exhaust, etc., and so its presence in breath samples does not necessarily imply recent smoking. Therefore, it is not a sensitive measure especially in youth where consumption may be low or sporadic.
Saliva samples can be messy to collect. They must be frozen until they can be analyzed, and the analysis of the samples is expensive. Thiocyanate is found in some leafy vegetables, and so false positive results can be obtained. Cotinene is considered the most accurate measure, but it is also more expensive to analyze. The collection of such samples is also difficult for studies that cover a large geographic area. Data collectors must be trained to collect and handle the samples properly.
