SurveyTip: Randomizing question answers is generally a good idea

Showing question answers in a random order reduces the risk of bias from the position.  

To understand this, think of what happens when you are asked to choose a question by a telephone interviewer.  When the list of choices are presented for a single choice question, you might be think of the first option as more of a fit, or perhaps the last option is top-of-mind.   The problem is even more acute when the person answering the survey has to comment on each of several attributes, for example when rating how well a company is doing for time taken to answer the phone, courtesy, quality of the answer, etc.   As survey creators, we don’t know exactly how the survey taker will react to the order, so the easiest way is to eliminate the potential for problems by presenting the options in a random order.  Telephone surveys with reasonable sample sizes are almost always administered with question options randomized for this reason, using CATI systems (computer assisted telephone interviewing).

When we create a survey for online delivery, a similar problem exists.  It could be argued that the survey taker can generally see all of the options so why is a random order needed?  But the fact is that we can’t predict how survey takers will react to the order of the options.  Perhaps they give more weight to the option nearest the question, or perhaps to the one at the bottom.  If they are filling out a long matrix or battery of ratings, perhaps they will change their scheme as they move down the screen.  They might be thinking something like “too many highly rated, that doesn’t seem to fit how I feel overall, so I’ll change, but I don’t want to redo the ones I already did”.    Often there could be an effect from one option being next to another that might be minimized by separating them, which randomizing will do (randomly).   The results from these options being next to each other would likely be very different:

  • Has a good return policy
  • Has good customer service
  • Items are in stock
  • Has good customer service

Some question types and situations are not appropriate for random ordering.  For example:

  • Where the option order is inherent, such as education level or a word based rating question (Likert scale)
  • Where there is an ‘Other’ or ‘Other – please specify’ option.  It is often a good idea to offer an ‘Other’ option for a list of responses such as performance measures in case the survey taker believes that the list provided isn’t complete, but the ‘Other’ should be the last entry.
  • A very long list, such as a list of stores, where a random order is likely to confuse or annoy the survey taker.

As with other aspects of questionnaire development, think about whether randomization will be best for the questions you include.

Idiosyncratically,
Mike Pritchard

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