Thursday, December 26, 2019

How many answer choices is best for a multiple-choice question? Probably not what you think.

Last week I discussed a quiz I developed  to help people analyze what they know and don't know about developing valuable and valid multiple-choice questions (mcqs). The mcq quiz:

Last week I shared the answer to one of the questions: Is “describe how to” a good behavior/action to use in a workplace learning objective? The answer is no and I explained why.

This week I'm discussing another question on the quiz. Here's the question.
What is the optimal number of answer choices for a multiple-choice question, according to research? (select the best answer) 
  • Three 
  • Four
  • Five 
The image below shows the pattern of replies from the 110 people who answered (so far). The green bar indicates the correct answer. The other two are incorrect.

Most people think MORE answers is better. That's because more answers choices appears to lower the chance of guessing correctly. 

In other words, four answer choices appears to have a 25% chance of guessing correctly. Five answers choices appears to have a 20% chance of guessing correctly. 

But the number of answer choices is not the only thing that determines the chance of guessing correctly. Quality of answer choices makes all of the difference.

Research shows that most people have a very hard time writing good multiple-choice questions. They have a hard time writing good answer choices. Mcqs with four or five answer choices often perform poorly because the answer choices are poorly written and make it easy to guess which are incorrect.

So research tells us to do the following when writing answer choices.

  1.  Learn how to write good wrong and right answer choices!
  2. Write two GOOD incorrect answer choices and one GOOD correct answer choice.
If you write mcqs, you cannot afford to have poorly written answer choices in your multiple-choice questions as they can damage assessments, people, and the organization.

Thanks to Anand Chandarana for reminding me to give others a link to an in-depth review of the research on the issue of number of answer choices.

Rodriguez, M. C. (2005). Three options are optimal for multiple‐choice items: A meta‐analysis of 80 years of research. Educational Measurement Issues and Practice, 24(2), 3 – 13. 

If you need to learn the secrets to designing valid mcq assessments, take my upcoming Write Learning Assessments course I'll teach you how to write GOOD correct and incorrect answer choices because these are essential to good mcqs and good mcq assessments. 

My take: If you design mcqs, you need to know how to do this difficult skill well. I'd love to teach you how.

No comments:

Post a Comment

Thank you for commenting!