Problem -
The sampling plan below was used in a statistical audit. The columns of the table list the strata indices, strata sizes, sample sizes and a description of the strata.
|
1
|
25
|
25
|
> $ 40,000.00
|
|
2
|
250
|
50
|
15,000.00 - 40,000.00
|
|
3
|
450
|
38
|
5,001.00 - 14,999.00
|
|
4
|
800
|
32
|
1,000.00 - 5,000.00
|
|
5
|
2,000
|
30
|
< 1,000.00
|
|
Totals
|
3,525
|
100
|
|
The means and standard deviations of erroneously paid dollars by strata were ($10,045, $623), ($8,756, $401), ($4,265, $211), ($809, $75) and ($53, $45), respectively
1. Calculate an estimate of the average error per case in the sampling frame (population) and a 90 % confidence interval for the same.
2. Calculate an estimate of the total dollars in error in the sampling frame (population) and a 90 % confidence interval for the same.