A common, although not universal, practice is to exclude respondents from research surveys who work in market research, marketing or the client’s industry. This will normally be the first question, so that they can be identified and excluded as quickly as possible and neither the respondent’s nor the interviewer’s time is wasted.
Exclusion by industry or profession is carried out partly to protect the confidentiality of the content of the survey, which could find its way to the desk of a competitor through any one of these routes. It is also carried out to avoid the over-representation of unusual behaviour and attitudes.
Someone who works in marketing or market research is likely to have different patterns of behaviour, particularly in relation to new products, and to respond differently to attitudinal questions to the public at large. People in these industries do of course make up a finite proportion of the markets and should ideally be included in their correct proportion for the data to represent fully the market in question. However, their proportion in any market is likely to be very small, and any over-representation could distort the study findings.
People who work in the industry that is the subject of the survey pose not only a threat to the security of the study, but may well have behavioural characteristics that are very different from the rest of the population. Their different behaviour could be due to staff discounts on the products in question or to a high degree of familiarity with the product. If they are buying the product at a staff shop or at a staff discount, then these people are genuinely outside the market and should be excluded both for this reason and for the security of the survey.
Some companies take the issue of security further and exclude journalists from some or all of their surveys. There is a risk that if journalists are shown a new concept or new product, they might be tempted to write a story about it, and there is a risk that what was a closely guarded new idea could quickly become the subject of a press article. The researcher should weigh up the risk of this and decide whether or not to exclude any profession based on the risk that it poses to the project. A behavioural study of the consumption of bread is unlikely either to reveal any new concepts to respondents or to stimulate the writing of an article. However, a study evaluating a new design for a car is likely to arouse a great deal of interest.
The security question is usually asked as a prompted question, with respondents shown a list of industries and professions. It is advisable to include in that jobs and professions in addition to those you wish to exclude. This reduces the possibility of a respondent trying to manipulate the outcome. Sometimes respondents will do this unintentionally. Most people’s natural inclination is to try to be helpful and answer questions positively. This may particularly occur early in an interview before fatigue sets in and whilst they are curious about the survey. Some people will ‘stretch’ the eligibility of someone in their household and say that they work in one of the industries or professions, believing that they are being helpful. If the only industries and professions offered are the exclusions, then respondents may be eliminated from the study unnecessarily.
Some respondents will deliberately try to manipulate the outcome, by saying that someone in their family works in one of the professions or industries because they realize that this is a screening criterion. They may wish not to be interviewed and, correctly, think that by saying that someone in their household works in one of the professions or industries they will be excluded. Or they may want to be interviewed and, mistakenly, think that qualification depends on someone in their household qualifying at this question.
Including a number of professions or industries in which many people work can reduce the effect of all of these biases, by allowing more people to answer positively without unnecessarily excluding themselves.
Source: Brace Ian (2018), Questionnaire Design: How to Plan, Structure and Write Survey Material for Effective Market Research, Kogan Page; 4th edition.