I took a test in class and found it to be difficult. So I asked in my WhatsApp group if others felt the same. 4/36 people replied yes they felt it difficult. Others did not respond either in yes or no. They may reply later. Can I infer anything about the whole class from this response. How to start a statistical approach to analyzing this situation about how the class felt?


1 Answer 1


No, you can't infer anything about the whole class from the people who responded because the people who responded are almost certainly not a random sample from your class. They are probably a biased sample, although the direction of the bias may depend on exactly how you worded the question.

For instance if you ask:

I found the recent test to be difficult. Did you? (YES/NO)

you may get different answers from a question like:

Did you find the recent test difficult? (YES/NO)

or from

How did you find the recent test (EASY/DIFFICULT)

  • $\begingroup$ How did you find the recent test (EASY/DIFFICULT)...Will this be a unbiased question? $\endgroup$ Commented Jul 15, 2019 at 13:53
  • $\begingroup$ An unbiased question of what? That is, you have to define some gold standard against which to judge bias. $\endgroup$
    – Peter Flom
    Commented Jul 16, 2019 at 10:03

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