STAT 854/454 Sampling Theory and Practice
Assignment 3
Due: Wednesday, February 25, in class
Format: standard A4 size paper, singlesided, with a cover page
1. An accounting ﬁrm is interested in estimating the error rate in a compliance audit it is
conducting. The population contains 828 claims, and each claim consists of 215 ﬁelds. The
ﬁrm audits 85 claims selected using SRSWOR, and all 215 ﬁelds are checked for errors for
each selected claim. It is found that one claim has errors in 4 of the 215 ﬁelds, one claim
has three errors, 4 claims have two errors, 22 claims have one error, and the remaining 57
claims have no error.
(a) Treating this as singlestage cluster sampling, estimate the error rate for all 828 claims.
Give a standard error for your estimate.
(b) Estimate (with standard error) the total number of errors in the 828 claims.
(c) Suppose that, instead of taking a cluster sample, the ﬁrm takes 85
×
215 = 18
,
275
ﬁelds from the 828
×
215 = 178
,
020 ﬁelds in the population using SRSWOR. If the
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This note was uploaded on 11/23/2010 for the course STAT 454 taught by Professor Da during the Fall '09 term at Waterloo.
 Fall '09
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