Sequential versus monadic testing

In this article you'll find information about: 

One answers “Which is best?,” the other answers “Is this good?”

1. Sequential stimulus exposure 

Results on sequential products can be influenced by what is known as the exposure effect. This effect is where respondents either consciously or subconsciously compare the stimuli they are being asked to evaluate to one another.

Let’s imagine a scenario: Three new ideas for chocolate bars are being tested, ideas A and B are not very appealing, and idea C is average. In a sequential test, respondents are likely to give idea C quite high scores, because they will be comparing it to ideas A and B. Now let’s imagine that ideas A and B are great, this is likely to result in idea C getting low scores, again because of the comparisons being made.

However, this isn’t always a bad thing. If your research question is “ which one of these is best?”, a sequential approach can be a great way of getting an answer, because you want respondents to draw comparisons between the stimuli you are showing them, and make a decision based on all of the information available. This is particularly true when you want to test stimuli that are very similar to each other.  Small differences that might not show up in monadic tests are more likely to have an impact on sequential methodologies, making it easier to make a business decision based on the data.

Sequential methodologies also tend to be cheaper, since you're able to ask the same respondent about multiple different stimuli, where you would have to run two or more surveys to accomplish this monadically.

2. Monadic stimulus exposure

Monadic products tend to be more reliable, and are better at answering “is this good?”. 

This is because the results for anyone stimulus are not affected by the other stimulus being tested. With a monadic test, you can be sure that the data you collect reflects the performance of a stimulus in absolute terms. This is then typically compared to a norm that is made up of multiple other stimuli, all tested in the same way.

What approach should I take? 

The approach you should take depends on your specific situation: 

  • Monadic testing is the gold standard for understanding the performance of a stimulus, and it is typically used later in the testing process. 
  • Sequential testing can be very useful, but it is normally best placed to screen earlier ideas, and separate the good from the bad.
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