21-PS-Monetary Unit Sampling AS2 V12

7/25/2019 21-PS-Monetary Unit Sampling AS2 V12

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The Audit Experience AS/2

Performance SupportMonetary Unit Sampling

(MUS)

The information in this performance support is provided to explain Monetary Unit Sampling(MUS) and al! through an example of MUS using the MUS "or!#oo! hile providing tips on

areas here users of this template sometimes run into trou#le$

This performance support ill cover the folloing topics (clic! on a lin! to go to the topic)%

"&AT 'S META*+ U'T SAM,-'.

&" 0 ' USE T&E MUS "*11

o .uidance ta#

o MUS 3alculations ta#

Step 4% 'nput parameters

Step 2% Enter the lines of data from the population

Step 5% ,erform the MUS reconciliation

o MUS Selections ta#

WHAT IS MONETA! UNIT SAMP"IN#$

Monetary Unit Sampling (MUS) is one form of statistical sampling that e use for tests of

details in our audits$ 't is defined in the 0TT- Audit Approach Manual (AAM) as a statistical

audit sampling method that can #e applied to a population of items expressed as monetary

amounts$ The sampling unit is defined as an individual monetary unit6 the li!elihood that an item

in the population ill #e selected is proportional to the num#er of monetary units contained in

the item$ asically7 hat this means is that this form of sampling selects items #ased on their

value6 the higher the value of an item7 the greater the chance of it #eing selected for testing$

MUS is often used for sampling those populations containing several items (i$e$7 hundreds or

thousands of individual items ithin the population)$ Using the Sampling 'nterval (,opulation

divided #y Sample Si8e) as the selection interval in applying Monetary Unit Sampling7

automatically results in selecting the appropriate num#er of items$ The items selected ill also

automatically include all items ith amounts individually greater than the sampling interval7 ifany7 and some portion of the smaller items in the population$

0TT- has created a tool that can assist you hen doing a Monetary Unit Sample called 9MUS

"or!#oo!$: 't can #e found in most AS/2 pac!s from ;ile7 e 0ocument in your AS/2 audit

file$

% &'''&'& *eloitte #lo+al Ser,ice- "imite.Partner- in "earning


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This or!#oo! should #e used hen information is o#tained electronically and there are many

lines of data$ &oever7 since Excel holds only 477?@ lines of information7 if the population

#eing sampled has more than 477?@ lines of data7 Excel cannot #e used$

;urther information on this sampling techniBue is detailed in the AAM Topic?=4< ,erform test

of details and Topic ?=4


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T',SD 't is essential to use a #lan! MUS "or!#oo! each time you do Monetary Unit Sampling$

+ou should not copy a prior years MUS "or!#oo! or use a MUS "or!#oo! from another audit

section6 this is #ecause a used MUS "or!#oo! may #e outdated or formatted specifically for the

existing sample (e$g$7 num#er of ros)$ 't is much easier to start your Monetary Unit Sample

ith a ne MUS "or!#oo! each time$

% &'''&'& *eloitte #lo+al Ser,ice- "imite.Partner- in "earning 1


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MUS Calculations tab

The MUS calculations ta# is the first place you ill #e reBuired to input data$

Step 1: Input parameters

"hen in the MUS 3alculations ta#7 you must start #y completing the first item discussed in the

.uidance ta#7 shon #elo%

'nput parameters (;inancial Statement Account7 ,opulation7 Sample Si8e7 and *andom Start

um#er) in the top section (ensure the *andom Start um#er is a ,S'T'FE num#er and not

greater than the sampling interval)$

"ithin the MUS 3alculations ta#7 you ill need to enter the folloing% ;inancial statement

account7 ,opulation7 Sample Si8e and random start num#er$ See #elo for an illustration$

What is the random start number?

The random start num#er is any positive num#er you select #eteen 8ero and the Sampling

'nterval$ This num#er needs to #e selected at random and selection method should #e

documented ithin your or!ing papers$ "e ordinarily use a random num#er generator to

determine this num#er$ Excel has a random num#er generator function #y using the folloing

formula%

G*A0ET"EE(#ottom num#er7 top num#er)

;or example7 entering into a cellG*A0ET"EE(474


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ith a random num#er #utton7 a ta#le of random num#ers7 or selecting num#ers from the serial

num#er of a currency note may #e used$



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Step 2: Enter the lines of data from the population

,ress the 9Add *os: #utton in the top section and enter the num#er of lines of data in your

population$ The necessary num#er of ros ill #e automatically inserted$ (,-EASE TE

-+ ,S'T'FE 'TEMS S&U-0 E '3-U0E0 ' T&E ,,U-AT'$ A--

E.AT'FE 'TEMS S&U-0 E *EMFE0 ;*M T&E ,,U-AT' A0 TESTE0

SE,A*ATE-+)$

3opy the data from your population file and paste it in the hite cells that ere inserted$ The

data should not #e more than three columns ide$ Typical data fields include '0 um#er7

0escription7 and Amount$

efore you enter the lines of data7 you must prepare the data to enter it into the or!sheet$

Ensure there are only three columns of data and determine the num#er of ros of data you have$

4 #tain the data

This depends on the population related to the ris! you are testing$ Example populations may #e%

A detail of customers and their account #alances for testing the ris!s identified in

accounts receiva#le$

A chec! register of payments made for testing the ris!s identified in accounts paya#le or

#an! reconciliation$

A detail of payroll expenses #y employee$

;or more information on populations7 refer to ,erformance SupportCTests of 0etails$

2 Manipulate the data for input

"hatever population you use to address the ris! #eing tested7 you must #e sure to use only

the positive items in the population$ egative items must #e removed and tested separately$



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;or example7 if you are testing the ris!s identified in accounts receiva#le and there are certain

customers that have credit #alances7 they must #e removed from the population in order for

the MUS sample to or! accurately$



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ext7 determine the columns that ill #e input into the or!sheet since the data cannot #e

more than three columns ide$

elo is an example of accounts receiva#le detail that could #e used for testing the ris!s

identified$

5 Add ros needed

o you need to determine the num#er of ros reBuired in the or!sheet$ As illustrated earlier7

the or!sheet has only four ros at the moment and you are li!ely to have more than four ros

of data$ To continue ith the example of inventory7 #elo is the data that as used to ma!e

selections for inventory testing to test the ris!s identified$



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As you can see7 there are many lines of data7 =< ros to #e exact$ +ou need to copy each line of

data into the MUS "or!#oo! in the hite area previously shon$ efore you can do this7 you

need to add ros$



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Ho do !ou add ros?

As shon a#ove7 you need to select the HAdd *osH #utton on the or!sheet and enter the

num#er of lines of data in your population file$

Add the num#er of ros you need (as shon a#ove) and you ill #e ready to copy the data$

(+ou can even add a fe extra ros Iust to #e on the safe sideD)

= 3opy the data

nce you have entered the correct num#er of ros7 copy the data from your population file7 and

paste it into the hite cell area that you Iust created$ "hen copying data%

Ma!e sure the data you ant to copy is no more than three columns ide$ 't should

typically contain an '0 um#er7 0escription7 and Amount$

,ut the first line of data into the first ro of hite cells next to 'tem J4$

0o not copy column headings or the total hen you copy data$ nly the individual data

lines should #e copied to the hite cells in this ta#$

"atch for hidden columns or ros in the population file$

% &'''&'& *eloitte #lo+al Ser,ice- "imite.Partner- in "earning '


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"hen you have copied the data7 your ta# should loo! li!e this%

Step ": #erform the MUS $econciliation%

The o#Iective of the MUS *econciliation is to determine hether the correct num#ers of sample

selections ere made$ 'f the correct sample selections ere made7 the MUS *econciliation ill

#alance$ 'f the reconciliation does not #alance7 it is important to revie the parameters and

calculated sample si8e to determine hat is causing the difference$

What is the MUS $econciliation?

After you have copied the data as shon a#ove and the selection process is completed7 you must

perform MUS reconciliation$ The o#Iective of the reconciliation is to determine hether the

correct num#er of sample selections as made$ The MUS reconciliation is on the #ottom left

hand side of the MUS 3alculationsC;igure ?=4


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Accidently deleting/entering information in the grey area of the or!sheet$

% &'''&'& *eloitte #lo+al Ser,ice- "imite.Partner- in "earning &


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nce the MUS reconciliation #alances7 press the 9*etrieve Selections: #utton in order to

automatically list the selections on the 9MUS Selections: ta#$

MUS Selections tab

nce you hit the *etrieve Selections #utton%After pressing the 9*etrieve Selections: #utton on

the MUS 3alculations ta#7 the selections ill #e automatically listed on this ta#$

3onfirm the total num#er of selections provided is the same num#er calculated on the MUS

3alculations Ta#$ 'f the num#ers are not the same7 revie the information to identify the

difference$

+ou should see the folloing selections appear on the MUS Selections ta#$

nce your selections are made7 you are ready to #egin testing$ otice ho all items L samplinginterval are automatically selected for testing$



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Will the number of selections ala!s be 1 item per selection?

The anser to this Buestion is no$ 't as mentioned earlier that the 4 next to this num#er in the

9um#er of Selections: column shos that this is 4 of the ? selections reBuired in the sample

si8e$ 't as mentioned that this might have #een a 27 57 or other positive num#er$ 'f it ere a 27

that means that this item ould count as 2 selections$ 'f it ere a 57 this item ould count as 5

selections$ 'n Monetary Unit Sampling7 4 item does not alays mean 4 selection$

;or example7 assume the total num#er of selections as @ instead of the ? that you have seen in

this example$ Assume that the folloing items ere shon in the MUS Selections ta#%

Will the sample si&e calculated in the MUS Wor'boo' ala!s be the same as hen

calculated manuall!?

o7 not alaysD This is #ecause the MUS "or!#oo! uses a random start num#er and selection

remainder$ 0epending on your random start num#er7 you might get a different sample si8e to test

to address the ris! identified$ +our num#er of selections ill alays #e the same #ut as some

selections count for more than one selection the actual num#er of items you get to test may vary$



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ote that this performance support does not replace the AAM$ 't should #e read in conIunction

ith the applica#le AAM topics7 as the manual states the reBuirements of our audit approach and

it provides further guidance$


Documents

21-PS-Monetary Unit Sampling AS2 V12