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Supplementary Chapter 19
Work Measurement, Learning Curves and Standards
TRUE/FALSE
1.Job and process analysis should follow work measurement.
ANS:F
2.Normal time needs to be adjusted for personal time and avoidable delays.
ANS:F
3.The performance rating factor and allowances are based upon human judgment.
ANS:T
4.For a time study, it is assumed the distribution of task times follow a poisson distribution.
ANS:F
5.When timing a work activity with multiple tasks, the general rule is to take the largest sample size estimate and use it for all activities or tasks.
ANS:T
6.Regression analysis is used to predict times based on different attributes of work.
ANS:T
7.Predetermined time standards are advantageous since they avoid needing multiple performance ratings.
ANS:T
8.After developing a pre-determined standards, stop-watch or work-sampling times studies need not be performed.
ANS:F
9.The groups best suited to set work standards are managers with input from industrial engineers.
ANS:F
10.For work sampling, p will never be known exactly since it is the population parameter that is being estimated.
ANS:T
11.A 90% learning curve implies faster learning than an 80% learning curve.
ANS:F
12.The learning curve does not apply to supervisory personnel, some skilled craftspeople or jobs that have non-repetitive job tasks.
ANS:T
13.Unavoidable delays should not be included in time studies.
ANS:F
14.A Performance Rating Factor (PRF) of 130% means a worker is slow and needs 30% more time.
ANS:F
MULTIPLE CHOICE
1.The outputs from a work measurement study leads to development of labor and equipment standards that are used for all of the following except
a. / Estimating work-force capacityb. / Fatigue and personal needs allowances
c. / Determining the cost of new work procedures
d. / Providing accurate information for scheduling and sequencing
ANS:B
2.A Performance Rating Factor (PRF) of 1.15 means
a. / The worker is working at a pace that is 15% faster than normalb. / The worker is working at a pace that is 15% slower than normal
c. / The worker is working at a pace that is 15% faster than standard time
d. / The worker needs to add 15% to the standard time
ANS:B
3.Allowances include time for all of the following except
a. / Fatigueb. / Equipment breakdowns
c. / Rest periods
d. / Poor scheduling
ANS:D
4.Which of the following is not part of the general approach to time study?
a. / Defines and evaluates each task and activityb. / Measures and records the time needed to perform each activity over a number of cycles
c. / Randomly observes work over a period of time to obtain a distribution of activities
d. / Determines the allowance factor for the work activity
ANS:C
5.All of the following are advantages of using regression analysis to determine standard time except
a. / A smaller cycle time is usedb. / Avoids the assumption of additive task times
c. / Statistically significant variables can be determined
d. / Confidence intervals for the prediction can be developed
ANS:A
6.Predetermined time standards are
a. / Macronotionsb. / Available in books and electronic tables
c. / A quick way to directly add up and get standard time
d. / Best for old and stable manufactured goods
ANS:B
7.Work standards
a. / Improve motivation if set by managersb. / Increase variability if set by works
c. / Are best set informally
d. / Work best when designed by workers
ANS:D
8.Work samplings
a. / Are based on normal distributionb. / Are used for repetitive work activities
c. / Determine the allowance factor
d. / Require a systematic (non-random) sample
ANS:C
9.All of following is true regarding learning curves except
a. / Not used for a pricing strategyb. / Are affected by a ratio of manual to machine work
c. / 80% learning curves exhibit a step initial decline and then level off
d. / Used in defense industries
ANS:A
10.The ______states that the cost of doing any repetitive task, work activity or project decreases as the accumulated experience of doing the job increases.
a. / Learning curveb. / Experience curve
c. / Deming philosophy
d. / Regression method
ANS:B
11.Which is not a practical issue when using learning curves?
a. / Incentive systems and bonus plans may increase learningb. / Complex intellectual learning will end quicker than learning simple tasks
c. / A contract phase-out may result in a lengthening of process times
d. / Keeping groups of employees together reaps productivity benefits
ANS:B
12.Personal fatigue and delay allowances are added to ______to arrive at ______.
a. / Standard time; normal timeb. / Standard time; desired time
c. / Normal time; desired time
d. / Normal time; standard time
ANS:D
SHORT ANSWER
1.Define work measurement and what it leads to from an operations perspective.
ANS:
Work measurement is a systematic procedure for the analysis of work and determination of times required to perform key tasks in processes. Work measurement leads to the development of labor and equipment time standards that are used for ...
•Estimating work-force and equipment capacity
•Establishing budgets
•Determining what new work procedures will cost
•Evaluating time and cost tradeoffs among process design alternatives
•Establishing wage-incentive systems
•Monitoring and evaluating employee performance and productivity
•Providing accurate information for scheduling and sequencing
Without accurate time standards, it is impossible to perform these tasks. Standard times are management’s anchor in an uncertain operating environment.
2.Define and relate normal time and standard time.
ANS:
Normal time = Observed Time*Performance Rating Factor or, OT*PRF
Normal time is the expected time required to perform some work activity at a normal pace under normal operating conditions and using a prescribed method. A normal pace is a pace that can be consistently performed by the average employee without undue fatigue under normal operating conditions. Typically, three or more highly-trained work study analysts make these independent judgments about “normal” performance and the average PRF.
Standard time = Normal Time (1 + Allowance Factor)
Standard time is the normal time adjusted for allowances. Allowances include time for labor fatigue and personal needs, equipment breakdowns, rest periods, information delays, etc. Most allowance factors are in the range of 10% to 20%.
3.Explain the use of regression analysis in establishing standard times.
ANS:
Regression analysis is used to predict times based on different attributes of the work rather than by adding up individual task times. Consider the problem for developing standard time estimates for installing electrical power lines. The regression model obtained from this analysis is:
Time = 0.237 + 2.804*Poles + 0.514*Wire + 1.09*Cross Arms + 0.170*Insulators + 1.50*Guy Wires
If the utility faces a situation in which they estimate installation of 4 poles, 1,500 feet of wire, 7 cross arms, 12 insulators and no guy wires, the predicted time for the job would be:
Time + 0.237 + 2.804*4 + 0.514*1,500 + 1.09*7 + 0.170*12 + 1.50*0 = 792,123 hours
4.Define time study and describe the basic procedures for conducting a time study.
ANS:
Time study is the development of a standard time by observing a task and analyzing it with the use of a stopwatch. The general approach to time study can be described as follows:
1.Define and evaluate each task and activity.
2.Measure and record the time needed to perform each task or activity over a number of cycles.
3.Rate the employee’s performance of each task or activity.
4.Use the performance rating to determine the normal task time.
5.Determine the allowance factor for the work activity.
6.Determine the standard time.
5.How do predetermined standards differ from time studies?
ANS:
Predetermined time standards describe the amount of time necessary to accomplish specific movements (called micromotions), such as moving a human hand a certain distance or lifting a one pound part. These small time estimates have been documented and are available in books and electronic tables. If a job, work activity or task can be broken down into such elemental tasks, an estimate of the normal time is made by adding up these predetermined times. This approach is especially appealing for developing standard times for new manufactured goods and some service tasks. Predetermined time standards were originally developed for labor-intensive use but data sets exist for machine micromovements such as an automated drill press.
6.Contrast Deming’s view of work standards with TQM views of work standards.
ANS:
Critics such as W. Edwards Deming have condemned work standards on the basis that they destroy intrinsic motivation in jobs and rob workers of the creativity necessary for continuous improvement. That is certainly true when managers dictate standards in an effort to meet numerical goals set up by their superiors. However, the real culprit in that case is not the standards themselves but managerial style. The old style of managing reflects Taylor’s philosophy: Managers and engineers think, workers do what they are told. A total quality approach suggest that empowered workers can manage their own processes with help from managers and professional staff.
7.Define work sampling. Give both manufacturing and service applications.
ANS:
Work sampling is a method of randomly observing work over a period of time to obtain a distribution of the activities that an individual or a group of employees perform. Work sampling determines the proportion of time spent doing certain activities on a job. Work sampling is based on statistics and, like all statistical procedures, it can suffer from sampling error and lead to erroneous conclusions simply by chance. Work sampling has been used to evaluate the work of nurses, production supervisors, doctors, secretaries, hotel maids, machinists, managers, package delivery employees and students.
8.Explain the concept of learning curves using an 80% learning curve as an example.
ANS:
The learning curve concept is that direct labor unit cost decreases in a predictable manner as the experience in producing the unit increases. For most people, for example, the longer you play a musical instrument or a video game the better and faster you become. The same is true in assembly operations, which was recognized in the 1920s at Wright-Patterson Air Force Base in the assembly of aircraft. Studies showed that the number of labor hours required to produce the fourth plane was about 80% of the amount of time spent on the second; the eighth plane took only 80% as much time as the fourth; the 16th plane, 80% of the time of the eighth, and so on.
9.Differentiate between an experience curve and the traditional learning curve.
ANS:
A broader extension of the learning curve is the experience curve. The experience curve states that the cost of doing any repetitive task, work activity or project decreases as the accumulated experience of doing the job increases. The terms “improvement curve,” “experience curve” and “manufacturing progress function” are often used to describe the learning phenomenon in the aggregate context. Marketing research, software design, developing engineering specifications for a water plant, accounting and financial auditing of the same client and implementing a software integration project are examples of this broader view. The idea is that as each time experience doubles costs decline by 10%.
PROBLEMS
1.Determine the sample size for the following time study given a standard deviation of four minutes and a 98% probability that the value of the sample mean is within 1.5 minutes?
a.28
b.15
c.39
d.41
ANS:
c.39
2.Determine the sample size for the following time study given a standard deviation of three ounces and a 92% probability that the value of the sample mean is within two ounces?
a.7
b.3
c.4
d.5
ANS:
a.7
3.For a work sampling study, there is a 95% probability that the processing time of an activity has an error of less than 0.06 minutes. The best estimate we have for “p” is 0.30. Determine the size sample that should be used for this work sampling study.
a.10
b.97
c.20
d.105
ANS:
b.97
4.For a work sampling study, there is a 95% probability that the processing time of an activity has an error of less than 0.06 minutes. The best estimate we have for “p” is 0.30. Determine the sample size needed for a work sampling study if no estimate of p is available.
a.161
b.105
c.97
d.267
ANS:
d.267
Exhibit 19.1
Following is a time study data table.
OBSERVATION CYCLES (Actual Time in Minutes)Work Task / 1 / 2 / 3 / 4 / 5 / 6 / 7
A / 0.12 / 0.17 / 0.19 / 0.11 / 0.15 / 0.16 / 0.20
B / 0.91 / 0.95 / 0.97 / 0.88 / 0.86 / 0.80 / 0.94
C / 1.52 / 1.48 / 1.40 / 1.60 / 1.65 / 1.52 / 1.47
______
5. Using Exhibit 19.1,if the performance rating factor for A = 1.15, B = 1.0 and C = 0.85, determine the normal time for the job.
a.2.58 minutes
b.2.37 minutes
c.18.00 minutes
d.0.791 minutes
ANS:
b.2.37 minutes
6.Given the data in Exhibit 19.1, if personal allowance is 7%, fatigue allowance is 12%, personal delay allowance is 9% and avoidable delay is 4 minutes, determine the standard time for the job.
a.3.04 minutes
b.0.66 minutes
c.3.30 minutes
d.23.14 minutes
ANS:
a.3.04 minutes
7.A job had a normal time of 2.43 minutes, an allowance of 20% and a forecast demand of 120 units per day. How long should it take to produce one day’s output?
a.58.3 minutes
b.291.6 minutes
c.349.9 minutes
d.243.0 minutes
ANS:
c.349.9 minutes
Exhibit 19.2
CYCLES (Actual Time in Seconds)Work Task / 1 / 2 / 3 / 4 / 5 / 6
Q / 25 / 30 / 27 / 31 / 22 / 20
R / 40 / 52 / 35 / 42 / 47 / 38
S / 60 / 62 / 50 / 55 / 62 / 58
______
8. Using Exhibit 19.2, if the performance rating factor for Q = 0.80, R = 1.10 and S = 1.10 and the total allowance is 17%, determine the normal time for the job.
a.125.99 seconds
b.147.40 seconds
c.153.10 seconds
d.130.83 seconds
ANS:
d.130.83 seconds
9.Given the data in Exhibit 19.2, with the allowance of 17%, determine the output per hour.
a.27.5 units per hour
b.28.6 units per hour
c.23.5 units per hour
d.161.9 units per hour
ANS:
c.23.5 units per hour
10.Based on data from a work sampling study, an office worker spends 21.5% of his time filing. Over the work sampling period, he was idle 12% of the time. If the worker filed 420 items in a 40-hour work week while performing other activities, and if his performance rating factor for filing was 0.95, determine the standard time, in minutes, that it took him to file an item .
a.1.17 minutes
b.0.14 minutes
c.6.08 minutes
d.1.31 minutes
ANS:
d.1.31 minutes
11.An employee was observed over an extended period of time for a work sampling study, with the following results:
ACTIVITY / PERCENTAGE OF TIME / PERFORMANCE RATING FACTOROn the Phone / 30% / 1.15
Filing / 35% / 0.70
Face-to-Face with Customer / 25% / 1.10
Idle / 10% / -----
While doing her job in a 40-hour work week, the employee helped 120 face-to-face, walk-in customers. Determine the standard time in minutes that it took her to help each face-to-face walk-in.
a.6.05 minutes
b.5.50 minutes
c.24.20 minutes
d.0.55 minutes
ANS:
a.6.05 minutes
12.A yacht manufacturer signed a contract to build five sailboats for a California resort. Assuming an 85% learning curve, how many labor-hours will it take to build all five sailboats if it took 7,000 standard hours to build the original sailboat?
a.4,799.9 hours
b.28,217.7 hours
c.35,000.0 hours
d.27,051.5 hours
ANS:
b.28,217.7 hours
13.A manufacturer made a commitment to supply 20 units of a product. The first unit took 1,200 hours to make, the second unit took 900 hours and the third unit took 768 hours. How many hours should it take to make the 20th unit?
a.12,581.88 hours
b.457.44 hours
c.1,200.00 hours
d.629.09 hours
ANS:
b.457.44 hours
14.A manufacturer made a commitment to supply 20 units of a product. The first unit took 1,200 hours to make, the second unit took 900 hours and the third unit took 768 hours. Determine the total number of hours required to make the first ten (10) items.
a.571.8 hours
b.6,290.94 hours
c.12,000.00 hours
d.7,578.48 hours
ANS:
d.7,578.48 hours
CE2 TB19/A Page 1
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