Versatility: Probably the greatest advantage of the questionnaire method is its versatility. Almost every problem of marketing research can be approached from the questionnaire standpoint. Every marketing problem involves people. Therefore, ideas relative to the problem and its solution can be obtained by asking these people about the problem. Many problems can be studied only by questionnaire. Knowledge, opinions, motivations, and intentions are usually not open to observation. Except where records have been maintained, past vents such as purchases of specific products can be studied only trough the questionnaire method. Similarly, it is normally feasible to observe personal activities, such as brushing teeth. All this does not mean that the questionnaire method can be used satisfactorily to solve all marketing problems. It can be used, however, to get some data relative to most problems.
Speed and cost: Questioning is usually faster and cheaper than observing. Interviewers have more control over their data gathering activities than do observers. As a result, less time is typically wasted in a questionnaire study. For example, in a research study to find whether consumers prefer beer in bottles or cans, one could either ask people their preference or wait in package liquor stores to observe which containers customers ask for when they come in to buy beer. The alter method would require observers to wait until customers came into the store to buy beer. Interviewers however, could proceed from one interviewee to another with no wait in between. Thus, the lost time would be less with the questionnaire method. Some events that take place over a time period, such as the number of trips to the supermarket in a week, would require lengthy observation, but a question on this behavior can be answered in a few seconds. In many cases, however, this advantage of the questionnaire may be negligible.
Despite the fact that the questionnaire method is widely used in marketing research, it has several important limitations,
Unwillingness of Respondent to provide Information: Most interviews are obtained at the sufferance of the respondent. The respondent answers the telephone to be greeted by an interviewer with a list of questions. The interviewers may be of little or no interest. The interviewer counts on the natural politeness and good nature of most people to gain their cooperation. But in some cases potential respondents will refuse to take the time to be interviewed or will refuse to answer some specific questions. Questions about income or about very personal subjects frequently meet refusals. The number of such refusals varies with individual interviewers and with the subject of the interview but in some cases refusals run as high as 55 percent of the attempted calls. A more typical refusal rate for a household survey is probably 5 to 10 percent. When questionnaire are sent through the mails, the percentage which is not returned may exceed 90 percent, although a non-response rate of 50 percent is more typical and among skilled researchers 25 percent or less is common.
Various methods of reducing unwillingness on the part of respondents have been developed. The most important of these is salesmanship on the part of the interviewer or a covering letter with mail questionnaire. Rewards in the form of premiums or cash often help to gain cooperation. Assurance that the information will be held in confidence and in no way will be related to the individuals may reduce refusals when data are particularly personal or of value to competitors.