The source for this post is the textbook Marketing Research by Aaker, Kumar and Day, supplemented by our own experience in the small markets of the Caribbean.
When trying to decide between a telephone or door-to-door (face-to-face) survey, these are some issues to consider:
- turn-around time - Because it is faster to call someone than to drive or walk to them, the turn around time for a telephone survey is shorter than for a face-to-face survey. In our experience, 400 telephone interviews can easily be done in less than 80 man-hours. Not so with face-to-face interviews
- length of the questionnaire - If the questionnaire is long or complex, it is often not desirable to conduct the interview over the phone. We have found that sometimes respondents are more willing to reveal certain personal information over the phone than in person and vice versa.
- distance to travel to respondents. If respondents live far apart, a telephone survey might be more cost-effective because of the cost and time of travel.
- level of supervision. It is easier (and more cost effective) to duly supervise interviewers from a centralized call area, than on the road. Mistakes are also easier caught and corrected, especially if data input happens at the same time, as we do at MarkStra.
- accessibility to respondents. Not all people have a telephone; interviewers can often not gain access to gated residential communities or apartments; interviewer safety may preclude visits to certain neighborhoods or during certain times of the day. Other groups are systematically inaccessible because of lifestyle or unwillingness to cooperate. Young men are often not home. When they are not, they are likely to be engaging in a group activity and cannot participate, even when called on a mobile phone. Workers in hospitality and health care often work shifts and may not be accessible during "regular" interviewing hours. In Curacao, we find that European Dutch people are systematically unavailable during dinner hours when interviewers are most likely to call or visit.
- product category. If the survey is about Ringtones, a phone is a pre-requisite. Hence a telephone survey is highly appropriate. If the survey is about a basic necessity (such as water or electricity), some respondents are likely to not have a phone, while their opinion is not only important, but possibly varies significantly from people with phones. If someone has an issue with the electricity company and has a phone, the road to a solution is probably much different than if he doesn't have a phone.
- sampling method used. Random sampling can be more effectively executed with a telephone survey. It is easier to call and call-back the chosen respondents, than to drive to their house with the risk of not finding them home or the risk of them not qualifying for the survey (f.i. because they are not a user of the product).
- the number of phones available at the call center
- budget- total cost is determined among others by the issues above
I started writing this post to explain the limitations of telephone surveys, but have realized that face-to-face interviews have at least as many limitations. Point 5, not being able to enter gated communities and apartments and interviewer safety issues are especially telling.
In the Caribbean, ROI and budget issues are especially important.Telephone surveys probably fit the budget better. Don't dismiss them as being less-than-ideal. Door-to-door surveys have at least as many limitations.