In this article I discuss a couple of basic principles to increase the quality of survey data from surveys. Although there are many factors involved with maximising survey data quality, understanding how long a survey should be, and the order in which questions should be asked are two easily controllable factors that can have a remarkable impact on the quality of data.
In a previous post I commented on a phenomenon known as "survey satisficing", which I believe is the biggest source of error leading to misleading data in online data collection. To review, satisficing occurs when a respondent becomes tired or unmotivated to answer questions thoughtfully and accurately. It is well known amongst behavioural scientists that human beings are prone to take mental shortcuts when performing tasks. Essentially it boils down to the fact that thinking requires considerable effort, which leads to a people taking mental shortcuts. Nobel prizes have been won understanding this phenomenon (e.g., Kahneman and Tversky), so it is fairly robust. The bad news is that survey satisficing leads to unreliable data. The good news is that it can be reduced, or even eliminated, by adhering to a few principles of effective survey design.
The first principle is knowing how long a survey should be. Perhaps the biggest contributor to satisficing is survey length. This is a no brainer; have you ever tried to complete a 40 minute survey, concentrating on every question? It is mentally exhausting, which works well for spy interrogations but not trying to understand customer attitudes! So, how long should a survey be to strike a balance between obtaining the right amount of data, while not being too long? Well, I would like to give a straight answer, but the truth is it depends. For an intervening survey where browsers are invited to complete a survey on entering a website, a survey should only consist of a few questions. Respondents are visiting the website for a reason (perhaps to shop), so do not have sufficient motivation to complete more than around five questions. At the other extreme, a survey sent out to employees may be much longer. They are motivated to complete the survey because of their affiliation. A forty minute survey in this situation may not be unreasonable. As a rule of thumb (suitable for general surveys emailed to opt-in panellists), a survey should be between 20-30 questions. After this, respondents tend to start responding inaccurately to "get it over with".
The second principle is knowing which order questions should be asked. Again, this principle is linked to survey satisficing. My own research, and the research of others, has shown that affective responses to stimuli generally decrease over time. What this means is that people's motivations to answer survey questions thoughtfully and accurately decrease steadily over time. However, this downward trend can be reduced by introducing unobtrusive interruptions, or countering the slide in mental alertness with easier questions. It is beyond the scope of this article to discuss how unobtrusive interruptions can be used to increase survey accuracy, but I would like to offer advice on the ordering of questions. To counter the steady decline in mental alertness, questions should be asked from the order of most difficult (i.e., requires most thinking), through to most easy. Open ended questions for example require considerable mental effort -they should be asked first. Demographic information (name, job title, etc.) require relatively little mental effort, and should be put at the end of the survey. Put specific questions somewhere near the beginning, and general questions somewhere near the end.
Implementing these two principles in your survey design can have a remarkable impact on the quality of data collected from online hosted surveys. People are not machines, and are often not capable of concentrating for extended periods of time. This steady decline in concentration can be countered by knowing how long a survey should be, and in which order questions should be asked. Knowing this will ensure higher quality responding, enabling more accurate and honest data analysis.