2
$\begingroup$

Let's say that I have a population of 10000, and I have a sample of 300 that have responded to an online survey. Of 10000 invitations, 300 hundred have replied. Would I be able to use the finite population correction for margin of error?

Population: 10000
Sample: 300
Response: 3%

$\endgroup$
3
  • $\begingroup$ if you have a representative sample why do you need corrections? $\endgroup$ Jun 22, 2011 at 11:09
  • 1
    $\begingroup$ It sounds like you have an intended sample size of 10000 and a 97% non-response rate. Your "population" is probably much, much greater than 10000. $\endgroup$
    – whuber
    Jun 22, 2011 at 14:40
  • $\begingroup$ Perhaps my understanding of "population" is misconstrued. Essentially, I'm trying to estimate the margin of error associated with a survey I recently ran on the clients of a company. What I'd like to be able to say is something like. "X% Clients of company Y agree that Z, with a margin of error of A." $\endgroup$ Jun 23, 2011 at 7:20

1 Answer 1

7
$\begingroup$

With a 3% response rate, it is highly likely that self-selection has made this a biased sample. whuber has also pointed out that 10000 may not be the whole population.

If the population was 10000 and if you had a random sample of 300 then you could make a finite population correction. Wikipedia suggests a multiplicative factor for the standard error of $$\sqrt{\dfrac{N-n}{N-1}}$$ which with $N=10000$ and $n=300$ is about $0.985$, not something that is going to make a lot of difference.

$\endgroup$
3
  • 1
    $\begingroup$ Yes, perhaps my terminology is incorrect and certainly self-selection is a problem in all online research. However, 10k is truely the universe for this population. So how do I calculate MoE? Or can I? $\endgroup$ Jun 23, 2011 at 7:22
  • $\begingroup$ The Wikipedia article also says that the FPC is intended for use when the sample size is greater than 5% of the population. For example, if your sample is 25%, the FPC is .8703, which could make more of a difference $\endgroup$
    – user7483
    Nov 20, 2011 at 4:13
  • $\begingroup$ Which formula for M of E is less important than whether to report one. There is a short discussion at stats.stackexchange.com/questions/7134/… that is relevant to this. Lots and lots of people report, for self-selected samples, inferential statistics derived from methods intended only for random samples. But as a reflective, informed person, you'll know that to do so is unsound and that margins of error will not have their nominal limits. At the post linked above I described a sort of workaround to this, which was met with mixed reviews. $\endgroup$
    – rolando2
    Nov 20, 2011 at 4:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.