s10 – 1 work study work measurement. s10 – 2 outline labor standards and work measurement ...

S10 – 1

Work Study

Work MeasurementWork Measurement

S10 – 2

OutlineOutline

Labor Standards and Work Labor Standards and Work MeasurementMeasurement

Historical ExperienceHistorical Experience

Time StudiesTime Studies

Predetermined Time Predetermined Time StandardsStandards

Work SamplingWork Sampling

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Labor Standards and Work Labor Standards and Work MeasurementMeasurement

Started early in the 20th centuryStarted early in the 20th century

Important to both manufacturing Important to both manufacturing and service organizationsand service organizations

Necessary for determining staffing Necessary for determining staffing requirementsrequirements

Important to labor incentive Important to labor incentive systemssystems

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Meaningful Standards Help Meaningful Standards Help DetermineDetermine

1.1. Labor content of items producedLabor content of items produced

2.2. Staffing needsStaffing needs

3.3. Cost and time estimatesCost and time estimates

4.4. Crew size and work balanceCrew size and work balance

5.5. Expected productionExpected production

6.6. Basis of wage incentive plansBasis of wage incentive plans

7.7. Efficiency of employeesEfficiency of employees

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Labor StandardsLabor Standards

May be set in four ways:May be set in four ways:

1.1. Historical experienceHistorical experience

2.2. Time studiesTime studies

3.3. Predetermined time standardsPredetermined time standards

4.4. Work samplingWork sampling

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Historical ExperienceHistorical Experience

How the task was performed last How the task was performed last timetime

Easy and inexpensiveEasy and inexpensive

Data available from production Data available from production records or time cardsrecords or time cards

Data is not objective and may be Data is not objective and may be inaccurateinaccurate

Not recommendedNot recommended

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Involves timing a sample of a Involves timing a sample of a worker’s performance and using it worker’s performance and using it to set a standardto set a standard

Requires trained and experienced Requires trained and experienced observersobservers

Cannot be set before the work is Cannot be set before the work is performedperformed

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1.1. Define the task to be studiedDefine the task to be studied

2.2. Divide the task into precise Divide the task into precise elementselements

3.3. Decide how many times to measure Decide how many times to measure the taskthe task

4.4. Time and record element times and Time and record element times and rating of performancerating of performance

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1.1. Compute average observed timeCompute average observed time

Average Average observed observed

timetime

Sum of the times recorded Sum of the times recorded to perform each elementto perform each element

Number of observationsNumber of observations==

1.1. Determine performance rating Determine performance rating and normal timeand normal time

Normal time = xNormal time = xAverage Average

observed observed timetime

Performance Performance rating factorrating factor

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1.1. Add the normal times for each Add the normal times for each element to develop the total normal element to develop the total normal time for the tasktime for the task

2.2. Compute the standard timeCompute the standard time

Standard time =Standard time =Total normal timeTotal normal time

1 -1 - Allowance factor Allowance factor

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Rest AllowancesRest Allowances

Personal time allowancePersonal time allowance 4% - 7% of total time for use of 4% - 7% of total time for use of

restroom, water fountain, etc.restroom, water fountain, etc.

Delay allowanceDelay allowance Based upon actual delays that occurBased upon actual delays that occur

Fatigue allowanceFatigue allowance Based on our knowledge of human Based on our knowledge of human

energy expenditureenergy expenditure

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1.1. Constant allowanceConstant allowance

(A)(A) Personal allowance ……………...Personal allowance ……………...55

(B)(B) Basic fatigue allowance …………Basic fatigue allowance …………44

2.2. Variable allowances:Variable allowances:

(A)(A) Standing allowance ………………Standing allowance ………………22

(B)(B) Abnormal positionAbnormal position

(i)(i) Awkward (bending) …………Awkward (bending) …………22

(i)(i) Very awkward (lying, Very awkward (lying, stretching) ……………………stretching) ……………………

77

Figure S10.1Figure S10.1

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(A)(A) Use of force or muscular energy in Use of force or muscular energy in lifting, pulling, pushinglifting, pulling, pushing

Weight lifted (pounds)Weight lifted (pounds)

20 ……………………………………20 …………………………………… 33

40…………………………………….40……………………………………. 99

60…………………………………….60……………………………………. 1717

(A)(A) Bad light:Bad light:

(i)(i) Well below recommended….Well below recommended…. 22

(ii)(ii) Quite inadequate…………….Quite inadequate……………. 55Figure S10.1Figure S10.1

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(E)(E) Atmospheric conditions Atmospheric conditions (heat and humidity) ……………(heat and humidity) ……………

0-100-10

(A)(A) Close attention:Close attention:

(i) Fine or exacting………………..(i) Fine or exacting………………..22

(ii) Very fine or very exacting……(ii) Very fine or very exacting……55

(A)(A) Noise level:Noise level:

(i) Intermittent—loud……………..(i) Intermittent—loud……………..22

(ii) Intermittent—very loud(ii) Intermittent—very loud or high-pitched………………... or high-pitched………………...

55


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(A)(A) Mental strain:Mental strain:

(i) Complex or wide span (i) Complex or wide span of attention.…………………….. of attention.…………………….. 44

(ii) Very complex…………………..(ii) Very complex………………….. 88

(I)(I) Tediousness:Tediousness:

(i) Tedious…………..………………(i) Tedious…………..……………… 22

(ii) Very tedious.……………………(ii) Very tedious.…………………… 55


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Time Study Example S1Time Study Example S1

Average observed time Average observed time = 4.0= 4.0 minutes minutesWorker rating Worker rating = 85%= 85%Allowance factor Allowance factor = 13%= 13%

Normal time = (Average observed time) x (Rating factor)Normal time = (Average observed time) x (Rating factor)

= (4.0)(.85)= (4.0)(.85)

= 3.4= 3.4 minutes minutes

Standard time = = =Standard time = = =Normal timeNormal time1 -1 - Allowance factor Allowance factor

3.43.41 - .131 - .13

3.43.4.87.87

= 3.9= 3.9 minutes minutes

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Allowance factor Allowance factor = 15%= 15%

PerformancePerformanceJob ElementJob Element 11 22 33 44 55 RatingRating

(A)(A) Compose and type letterCompose and type letter 88 1010 9 9 21*21* 1111120%120%

(B)(B) Type envelope addressType envelope address 22 33 2 2 1 1 33105%105%

(C)(C) Stuff, stamp, seal, andStuff, stamp, seal, and 22 11 5*5* 2 2 11110%110%

sort envelopes sort envelopes

Cycle Observed (in minutes)Cycle Observed (in minutes)

1.1. Delete unusual or nonrecurring observations (marked with *)Delete unusual or nonrecurring observations (marked with *)2.2. Compute average times for each elementCompute average times for each element

Average time for A Average time for A = (8 + 10 + 9 + 11)/4 = 9.5= (8 + 10 + 9 + 11)/4 = 9.5 minutes minutesAverage time for B Average time for B = (2 + 3 + 2 + 1 + 3)/5 = 2.2= (2 + 3 + 2 + 1 + 3)/5 = 2.2 minutes minutesAverage time for C Average time for C = (2 + 1 + 2 + 1)/4 = 1.5= (2 + 1 + 2 + 1)/4 = 1.5 minutes minutes

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1.1. Compute the normal time for each elementCompute the normal time for each element

Normal time for A Normal time for A = (9.5)(1.2) = 11.4= (9.5)(1.2) = 11.4 minutes minutesNormal time for B Normal time for B = (2.2)(1.05) = 2.31= (2.2)(1.05) = 2.31 minutes minutesNormal time for C Normal time for C = (1.5)(1.10) = 1.65= (1.5)(1.10) = 1.65 minutes minutes

Normal time = (Average observed time) x (Rating)Normal time = (Average observed time) x (Rating)

1.1. Add the normal times to find the total normal timeAdd the normal times to find the total normal time

Total normal time Total normal time = 11.40 + 2.31 + 1.65 = 15.36= 11.40 + 2.31 + 1.65 = 15.36 minutes minutes

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1.1. Compute the standard time for the jobCompute the standard time for the job

Standard time =Standard time =Total normal timeTotal normal time

1 -1 - Allowance factor Allowance factor

= = 18.07= = 18.07 minutes minutes15.3615.361 - .151 - .15

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Determine Sample SizeDetermine Sample Size

How accurate we want to beHow accurate we want to be

The desired level of confidenceThe desired level of confidence

How much variation exists within How much variation exists within the job elementsthe job elements

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Required sample size = n = Required sample size = n = 22

zszshxhx

wherewhere hh == accuracy level accuracy level desired in percent of the job element desired in percent of the job element expressed as a decimalexpressed as a decimal

zz == number of standard number of standard deviations required for the desired level deviations required for the desired level of confidenceof confidence

ss == standard deviation of standard deviation of the initial samplethe initial sample

xx == mean of the initial mean of the initial samplesample

nn == required sample sizerequired sample size

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Required sample size = n = Required sample size = n = 22

zszshxhx

wherewhere hh == accuracy level accuracy level desired in percent of the job element desired in percent of the job element expressed as a decimalexpressed as a decimal

zz == number of standard number of standard deviations required for the desired level deviations required for the desired level of confidenceof confidence

ss == standard deviation of standard deviation of the initial samplethe initial sample

xx == mean of the initial mean of the initial samplesample

nn == required sample sizerequired sample size

Desired Confidence

(%)

z Value (standard deviation required for

desired level of confidence)

90.0 1.65

95.0 1.96

95.45 2.00

99.0 2.58

99.73 3.00

Common z Values

Table S10.1

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Desired accuracy with Desired accuracy with 5%5%Confidence level Confidence level = 95%= 95%Sample standard deviation Sample standard deviation = 1.0= 1.0Sample mean Sample mean = 3.00= 3.00

n = n = 22

zszshxhx

n n = = 170.74 ≈ 171= = 170.74 ≈ 17122

1.96 x 1.01.96 x 1.0.05 x 3.05 x 3

h h = .05= .05 x x = 3.00= 3.00 s s = 1.0= 1.0

zz = 1.96 ( = 1.96 (from from Table S10.1Table S10.1 or Appendix I or Appendix I))

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n = n = 22

zszsee

If desired accuracy h is expressed as an absolute If desired accuracy h is expressed as an absolute amount, substitute e for hx, where e is the amount, substitute e for hx, where e is the absolute amount of acceptable errorabsolute amount of acceptable error

VariationsVariations

When the standard deviation s is not provided, When the standard deviation s is not provided, it must be computedit must be computed

s = = s = = ∑∑(x(xii - x) - x)22 ∑∑(Each sample observation - x)(Each sample observation - x)22

n n - 1- 1 Number in sampleNumber in sample - 1 - 1

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New ToolsNew Tools

With PDA software, you can study With PDA software, you can study elements, time, performance rate, and elements, time, performance rate, and statistical confidence intervals can be statistical confidence intervals can be created, created, edited, edited, managed, managed, and loggedand logged

Reduces or Reduces or eliminates eliminates the need the need for data entryfor data entry

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Predetermined Time Predetermined Time StandardsStandards

Divide manual work into small basic Divide manual work into small basic elements that have established timeselements that have established times

Can be done in a laboratory away from Can be done in a laboratory away from the actual production operationthe actual production operation

Can be set before Can be set before the work is actually the work is actually performedperformed

No performance No performance ratings are necessaryratings are necessary

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MTM TableMTM Table


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MTM ExampleMTM Example

Weight - less than 2 poundsWeight - less than 2 poundsConditions of GET - easyConditions of GET - easyPlace accuracy - approximatePlace accuracy - approximateDistance range - 8 to 20 inchesDistance range - 8 to 20 inches

Element DescriptionElement Description ElementElement TimeTime

Get tube from rackGet tube from rack AA2AA2 3535

Get stopper, place on counterGet stopper, place on counter AA2AA2 3535

Get centrifuge tube, place at sample tableGet centrifuge tube, place at sample table AD2AD2 4545

Pour (3 seconds)Pour (3 seconds) PTPT 8383

Place tubes in rack (simo)Place tubes in rack (simo) PC2PC2 4040

Total TMUTotal TMU 238238

.0006 x 238 =.0006 x 238 = Total standard minutes Total standard minutes = .14= .14

Table S10.2Table S10.2

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Estimates percent of time a worker Estimates percent of time a worker spends on various tasksspends on various tasks

Requires random observations to Requires random observations to record worker activityrecord worker activity

Determines how employees allocate Determines how employees allocate their timetheir time

Can be used to set staffing levels, Can be used to set staffing levels, reassign duties, estimate costs, and reassign duties, estimate costs, and set delay allowancesset delay allowances

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Advantages of work samplingAdvantages of work sampling Less expensive than time studyLess expensive than time study

Observers need little trainingObservers need little training

Studies can be delayed or interrupted Studies can be delayed or interrupted with little impact on resultswith little impact on results

Worker has little Worker has little chance to affect chance to affect resultsresults

Less intrusiveLess intrusive

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Disadvantages of work samplingDisadvantages of work sampling Does not divide work elements as Does not divide work elements as

completely as time studycompletely as time study

Can yield biased results if observer Can yield biased results if observer does not follow random patterndoes not follow random pattern

Less accurate, especially when Less accurate, especially when job element times are shortjob element times are short


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1.1. Take a preliminary sample to obtain Take a preliminary sample to obtain estimates of parameter valuesestimates of parameter values

2.2. Compute the sample size requiredCompute the sample size required

3.3. Prepare a schedule for random Prepare a schedule for random observations at appropriate timesobservations at appropriate times

4.4. Observe and record worker activitiesObserve and record worker activities

5.5. Determine how workers spend their Determine how workers spend their timetime

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Determining the sample sizeDetermining the sample size

n =n =zz22 p p(1 -(1 - p p))

hh22

wherewhere nn == required required sample sizesample size

zz == standard standard normal deviate for desired normal deviate for desired confidence levelconfidence level

pp == estimated estimated value of sample proportionvalue of sample proportion

hh == acceptable acceptable error level in percenterror level in percent

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Work Sampling ExampleWork Sampling Example

Wants employees idle 25% of the timeWants employees idle 25% of the timeSample should be accurate within 3%Sample should be accurate within 3%Wants to have 95.45% confidence in the resultsWants to have 95.45% confidence in the results

n =n =zz22 p p(1 -(1 - p p))

hh22

wherewhere nn == required sample required sample sizesizezz == 22 for a for a 95.45%95.45% confidence levelconfidence levelpp == estimate of idle estimate of idle proportion proportion = 25% = .25= 25% = .25hh == acceptable error acceptable error of of 3% = .033% = .03

n n = = 833= = 833 observations observations(2)(2)22 (.25)(.75) (.25)(.75)

(.03)(.03)22

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Work Sampling ExampleWork Sampling ExampleNo. of No. of

ObservationsObservations ActivityActivity

485485 On the phone or meeting with a welfare clientOn the phone or meeting with a welfare client

126126 IdleIdle

6262 Personal timePersonal time

2323 Discussions with supervisorDiscussions with supervisor

137137 Filing, meeting, and computer data entryFiling, meeting, and computer data entry

833833

All but idle and personal time are work related. All but idle and personal time are work related.

Percentage idle time Percentage idle time = (126 + 62)/833 = 22.6%.= (126 + 62)/833 = 22.6%.

Since this is less than the target value of Since this is less than the target value of 25%,25%, the workload needs to be adjusted.the workload needs to be adjusted.

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Work Sampling Time Work Sampling Time StudiesStudies

SalespeopleSalespeople


Telephone Telephone salessales12%12%

Telephone Telephone within firmwithin firm

13%13%

Lunch and Lunch and personalpersonal

10%10%

Meetings Meetings and otherand other

8%8%

Paperwork17%

Travel20%

Sales in person

20%

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Work Sampling Time Work Sampling Time StudiesStudies


Productive work67%

Startup/pep talkStartup/pep talk3%3%

Breaks and lunchBreaks and lunch10%10%

Dead time Dead time between tasksbetween tasks

13%13%

CleanupCleanup3%3%

Unscheduled tasks Unscheduled tasks and downtimeand downtime

4%4%

Assembly-Line Assembly-Line EmployeesEmployees

s10 – 1 work study work measurement. s10 – 2 outline labor standards and work measurement ...

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