1. Operations Management Work Measurement Supplement 10
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2. Outline Labor Standards and Work Measurement Historical Experience
Time-Studies
Predetermined Time Standards
Work Sampling
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3. Learning Objectives
When you complete this supplement, you should be able to :
Identify or Define:
Four ways of establishing labor standards
Describe or Explain:
Requirements for good labor standards
Time study
Predetermined time standards
Work sampling
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4. Uses of Labor Standards
Costing labor content of products
Planning staffing needs
Estimating time and cost for bids
Planning production (crew size and work balance)
Basing wage-incentive plans
Determining employee efficiency
You might note here that labor standards are of use both before production (planning, bidding, etc.) and during producing (wage-incentive, determining efficiency, etc.)
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5. Sources of Labor Standards
Historical experience
Time studies
Predetermined time standards (MTM)
Work sampling
Most of these methodologies rely on the job actually being performed..
© 1995 Corel Corp.
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6. Time Studies Labor standards are based on observing worker doing task
Observe only a sample of work
Use average time & pace to set standard
Disadvantages
Requires a trained & experienced analyst
Standard cannot be set before task is performed
Here it may be helpful to discuss why something, which often looks to students to be so simple, is really not. What problems does one encounter in doing a time study? Why factors make it more complex than it appears?
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7. The Eight Steps to Conducting a Time Study
Define the task to be studied (after a methods analysis)
Break down the task into precise elements
Decide how many times each element of the task must be measured
Record the times and ratings of performance for the task elements
Compute the average observed cycle time (element times adjusted for unusual influences)
It is sometimes helpful to actually walk students through a time study in the classroom. The task does not have to be complex - perhaps as simple as sharpening a pencil. Ask them to consider sources of variance as the task is performed on different pencils by different people.
Students should also be asked how one determines the appropriate adjustments for unusual influences.
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8. The Eight Steps to Conducting a Time Study - continued
Compute the normal time for each task element:
Normal time = (Average actual cycle
time) x (Rating factor)
Sum the normal times for each element to develop a total normal time for the task
Compute the standard time:
At this point in the process, students should be asked to determine the appropriate waiting factor and allowances. How does one determine the rating factor for a particular worker? What allowances are appropriate in a given situation, and how long should they be?
Standard time =
Total normal time
1- Allowance factor
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9. Allowances
Personal time allowance - 4% - 7% of total time - use of restroom, water fountain, etc.
Delay allowance - based upon actual delays that occur
Fatigue allowance - to compensate for physical or mental strain, noise level, tediousness, heat and humidity, assumption of an abnormal position, etc.
Some thoughts on allowances.
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10. Time Studies - Sample Size
h = accuracy level desired as percent of job element, expressed as a decimal (5% = 0.05)
z = number of standard deviations required for the desired level of confidence
s = standard deviation of the initial sample
x = mean of the initial sample
The need for calculation of the appropriate sample size was probably covered earlier. If not, one should at least introduce the equation and its use.
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11. Considerations in Determining Sample Size
How accurate do you want to be?
What level of confidence do you want your measurements to have?
How much variation exists within the job elements?
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12. Common z values
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13. Time Study Equations Nonwork time Allowance factor = Total time
 Element times
Average element time =
Number of cycles
Normal time =
Average element time * Perf. Rating
If you have actually conducted a time study in the classroom, you should demonstrate the use of these equations.
Total normal time
Standard time =
1 - Allowance factor
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14. Predetermined Time Standards
Labor standards are set from times in published tables (e.g., MTM Table)
Procedure
Divide manual work into basic elements
Look up basic element times in table; sum
Advantages
Times established in laboratory setting
Useful for planning tasks
Widely accepted by unions
A useful exercise in applying predetermined time standards can be to have teams of three or four students each develop the time standard for a particular task as a homework assignment. Have them bring the completed standards to the next class and discuss the results.
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15. MTM Table for Reach Motion
Hand in
Time TMU
Motion
Distance A B C A B
Moved (in)
3/4 or less
2.0
2.0
2.0
1.6
1.6 1
2.5
2.5
3.6
2.3
2.3 2
4.0
4.0
5.9
3.5
2.7
A Reach to object in fixed location. B Reach to object in variable locations. C Reach to object jumbled with others.
1 TMU = minutes
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16. Sample MTM Table for GET and PLACE Motions
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17. Work Sampling
Labor standard is set using output and % of time worker spends on tasks
Involves observing worker at random times over a long period
Advantages
Less expensive than time studies
Observer requires little training
Disadvantages
Ineffective with short cycles
Discussion of this methodology should emphasize its use in service organizations.
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18. Work Sampling Used for Ratio delay studies Setting labor standards
Measuring worker performance
It would be helpful at this point to note the use of Work Sampling as a diagnostic tool.
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19. The Seven Step Work Sampling Procedure
Take a preliminary sample to obtain an estimate of the parameter value
Compute the sample size required
Prepare a schedule for observing the worker at appropriate times
Observe and record worker activities; rate worker performance
One point to bring out here is that observations should be conducted at random intervals. Students could be asked to conduct a study of one of their classmates or a worker in the college or university community. One issue this might raise is that of the impact of the observer on the worker being observed.
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20. Work Sampling Procedure - continued
The Seven Step
Work Sampling Procedure - continued
Record the number of units produced during the applicable portion of the study
Compute the normal time per part
Compute the standard time per part
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21. Work Sampling - Sample Size
p = estimated value of sample proportion (of time worker is observed busy or idle)
h = accuracy level desired in percent, expressed as a decimal
The issue to be raised here is that this calculation gives an estimate of sample size. If the sample proportion turns out to differ significantly from the estimate, the sample size must be recalculated.
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22. Work Sampling Equations
(Total Time) (% of time working) (Rating)
Normal Time =
Number of units Produced
Normal Time
Standard Time =
1 - Allowance
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23. Figure S10.3
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