Session 9, Part D:
The Effect of Sample Size

In This Part: Sample Size 20 | Comparing Sample Sizes 10 and 20 | Box Plot Comparisons

 In order to investigate whether samples of 20 sub-regions are more likely to produce better estimates than samples of 10 sub-regions, you will need to consider repeated sampling results for samples of size 20. Here is the stem and leaf plot for 100 estimates of sample size 10: Here is the stem and leaf plot for 100 estimates of sample size 20: Problem D1 Compare the two distributions above. In particular, look at how many estimates for each fall in the interval 450 to < 550 (i.e., the 4H and 5L stems). What does this suggest about the effect of sample size on the accuracy of estimation?

 Which distribution has more estimates "closer" to the actual answer of 500?   Close Tip Which distribution has more estimates "closer" to the actual answer of 500?

Problem D2

Now let's revisit our table of intervals.

 a. Use the 100 estimates from samples of size 20 to determine the proportion of estimates in each of the intervals.

 Interval Interval Length Proportion of Estimates in Interval Sample Size 10 Sample Size 20
 350-650 300 100/100 375-625 250 98/100 400-600 200 94/100 425-575 150 84/100 450-550 100 69/100 475-525 50 37/100

 Interval Interval Length Proportion of Estimates in Interval Sample Size 10 Sample Size 20
 350-650 300 100/100 100/100 375-625 250 98/100 100/100 400-600 200 94/100 98/100 425-575 150 84/100 94/100 450-550 100 69/100 83/100 475-525 50 37/100 55/100