Chapter 15 Slides Flashcards
(67 cards)
representative sample
a sample in which the characteristics in the sample are approximately the same as those of the population
auditors can’t know if their sample is representative, but they can increase the likelihood by using care in… (3)
- designing the sampling process
- sample selection
- evaluation of sample results
all samples have two types of risks/the risk of two types of errors
sampling and nonsampling
sampling risk
the risk that the sample does not represent the population; eliminated if sample is 100% (too costly)
2 ways to control sampling risk
- increase sample size (inverse relationship)
- sample selection method (better when allows for statistical extrapolation)
nonsampling risk
risk that the auditor reaches an incorrect conclusion for any reason not related to sampling risk
common reasons for nonsampling risk (2)
- auditor’s failure to recognize exceptions (distracted, fatigued, bored, mistake)
- ineffective or not appropriate audit procedures (trace vs. vouch, use of analytical review when should sample)
2 ways to combat nonsampling risk
- proper training on audit testing
- proper supervision and review
Type I Error
false rejection; auditor concludes that IC are ineffective when they are effective (qualified/adverse opinion when actually fairly stated)
Type II Error
false acceptance; auditor concludes ICs are effective when they’re ineffective (overreliance on IC, control risk too low) (unmodified opinion when actually misstated)
3 phases in both statistical and nonstatistical sampling
- plan the sample
- select the sample and perform the tests
- evaluate the results (to consider acceptability of IC/Trx of population)
statistical sampling
applies mathematical rules so the auditor can quantify sampling risk in planning the sample (step 1) and evaluating the results (step 3)
2 reasons to use statistical sampling
- allows for quantifying sampling risk in the planning stage
- allows for evaluating the results statistically
95% confidence level means __ sampling risk (ARO)
5%
nonstatistical sampling
doesn’t quantify sampling risk but can provide effective results in audits when properly designed
nonstatistical/nonprobabilistic sampling is based on the __ __ rather than a statistical method of sample selection
auditor’s judgment
two types of nonprobabilistic sampling
haphazard sampling, block selection
3 probabilistic sample selection methods
- simple random sample selection
- systematic sample selection
- monetary unit sampling/probability proportional to size sample selection
probabilistic sample selection
auditor randomly selects items such that each item has a known probability of being included in the sample
simple random sample selection
a. random number generator
b. with (rare) or without replacement
c. results are not sequential, need to order them
d. i.e., sales invoices or monetary units
simple random sample selection
every possible combination of population items has an equal chance of being included in the sample
3 ways auditors often generate random numbers
- electronic spreadsheets
- random number generators
- generalized audit software
systematic sample selection
- determine total population, divide by sample size = interval needed
- random number within interval to begin
- advantage: results are sequential
- weakness: once interval is set, might miss a consistent error/fraud
probability proportional to size (PPS) sample selection
divide population into subpopulations (dollar size) taking larger samples from larger dollar population (emphasis on large dollar amounts)