Exercise

# Exercise 10. Sample size

So far we have said that the difference between the proportion of Democratic voters and Republican voters is about 10% and that the standard error of this spread is about 0.2 when \(N=25\). Select the statement that explains why this sample size is sufficient or not.

Instructions

**50 XP**

##### Possible Answers

- This sample size is sufficient because the expected value of our estimate \(2\bar{X}-1\) is \(d\) so our prediction will be right on.
- This sample size is too small because the standard error is larger than the spread.
- This sample size is sufficient because the standard error of about 0.2 is much smaller than the spread of 10%.
- Without knowing
`p`

, we have no way of knowing that increasing our sample size would actually improve our standard error.