Transcript 15.2 Single - Factor (One - Way) Analysis of Variance
Chapter 8 Human Resources in Operations Management
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Human Resources In Strategic Planning
Importance of employees Education & training - long-term investments Employees broad latitude in jobs trained in wide range of skills empowered to improve quality & service
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2000 by Prentice-Hall, Inc Ch 8 - 2 2
Evolution of Job Design
1900s to 1960s Scientific Management/Assembly Lines Task specialization Minimal worker skills Repetition Minimal job training Mass production Piece-rate wages Time as efficiency Minimal job responsibility Tight supervisory control
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Evolution Of Job Design
1970s to 1990s Horizontal job enlargement Vertical job enlargement Extensive job training Job responsibility & empowerment Job control Training & education Job rotation Higher skill levels Team problem solving Employee involvement & interaction Focus on quality
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Elements of Job Design
Worker Analysis Task Analysis Environmental Analysis
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Task Analysis
Description of tasks Task sequence Function of tasks Frequency of tasks Criticality of tasks Relationship with other jobs/tasks Performance requirements Information requirements Control requirements Error possibilities Task duration(s) Equipment requirements
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Worker Analysis
Capability Performance Evaluation Skill level Physical Mental stress Boredom Motivation Number of workers Level of responsibility Monitoring level Quality responsibility Empowerment level
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Environmental Analysis
Work place location Process location Temperature and humidity Lighting Ventilation Safety Logistics Space requirements Noise Vibration
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Job Analysis
Study how job should be done Tools: Process flowchart - analyze process steps Worker-machine chart - study time utilization Motion study - study human motions in tasks
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Process Flowchart
Job: Page: Copying Job 1 Date: 9/11 Analyst: Calvin Desk operator fills out work order Work order placed in “waiting job” box Job picked up by operator and read Job carried to appropriate copy machine Operator waits for machine to vacate Operator loads paper Operator sets machine Operator performs and completes job Operator inspects job for irregularities Job filed alphabetically in completed shelves Job waits for pick up Job moved by cashier for pick up Cashier completes transaction Cashier packages job (bag, wrap, or box)
D D D D D D D D D D D D D D
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Job Photo-Id Cards Time -1 Operator -2 Worker-Machine Chart Date 10/14 Key in customer data on card Time 2.6
Photo Machine Idle -3 Feed data card in 0.4
Position customer for photo 1.0
Accept card Idle -4 Take picture 0.6
Begin photo process -5 -6 -7 Idle 3.4
Photo/card processed -8 -9 -10 Inspect card & trim edges 1.2
Idle
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Motion Study
Frank & Lillian Gilbreth Find one “best way” to do task Divide task into therbligs search, select, grasp, hold Use videotape to study motions
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General Guidelines For Motion Study
Efficient Use Of Human Body Work - simplified, rhythmic & symmetric Hand/arm motions - coordinated & simultaneous Employ full extent of physical capabilities Conserve energy - use machines, minimize distances, use momentum Tasks - simple, minimal eye contact & muscular effort, no unnecessary motions, delays or idleness
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Efficient Arrangement Of Workplace Tools, material, equipment - designated, easily accessible location Seating & work area - comfortable & healthy Efficient Use Of Equipment Equipment & mechanized tools enhance worker abilities Use foot-operated equipment to relieve hand/arm stress Construct & arrange equipment to fit worker use
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Work Measurement
Estimate standard time required to perform a task Methods of performing work measurement Stopwatch time study Elemental standard time files Predetermined motion times Work sampling
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Time Study Observation Sheet Identification of operation
Sandwich Assembly
Date Operator
Smith
Approval
Jones
Observer
Russell
1 2 3 4 Cycles 5 6 7 8 9 10
t
Summary
t RF Nt
1 2 3 4
Grasp and layout bread slices
t
.04 .05
R
.04 .38
.05 .04
.06 .05
.06
.06 .07 .05
.72 1.051.40 1.76 2.13 2.50 2.89 3.29
.53 .053 1.05 .056
Spread mayonnaise on both slices Place ham, cheese, and lettuce on bread
t
.07
R
.11
t
.12
.06 .07 .08
.07
.07
.08
.10 .09
.08
.77 .077
1.00
.077
.44 .79 1.13 1.47 1.83 2.21 2.60 2.98 3.37
.11
.14 .12
.13
.13
.13
.12
.14
.14 1.28 1.28 1.10 .141
R
.23
.55
.93
1.25 1.60 1.96 2.34 2.72 3.12 3.51
t
.10
Place top on sandwich, slice and stack
R
.33
.12
.08 .09
.11
.11
.10
.10
.12
.10
1.03 1.03 1.10 .113
.67 1.01 1.34 1.71 2.07 2.44 2.82 3.24 3.61
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Stopwatch Time Study Basic Steps
1. Establish the standard job method 2. Break down the job into elements 3. Study the job 4. Rate the worker’s performance (RF) 5. Compute the average time ( t )
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6. Compute the normal time Normal Time = (Elemental average) (rating factor) Nt = ( t )(RF) Normal Cycle Time = NT = Nt 7. Compute the standard time Standard Time = (normal cycle time) (1 + allowance factor) ST = (NT) (1 + AF)
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Incentive Piece-Rate Example
Piece-rate is $0.04 per sandwich What would average worker earn per hour?
60 min min/ sandwich or 135 sandwiches Wage rate = (135)(0.04) = $5.40
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Number Of Cycles
n zs eT 2 where z z value for desired confidence level s = x i x 2 n sample sta ndard deviation T = average job cycle time e = degree of error from true mean
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Number Of Cycles
Average cycle time (without Rating Factor) =0.361
Computed standard deviation = 0.03
Company wants to be 95% confident that computed time is within 5% of true average time n zs eT 2 ) 0 05 0 361 ) 2 11
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Work Sampling
A technique for determining the proportion of time a worker or machine spend on various activities Involves brief, random observations Useful for non-repetitive tasks E.g., secretary, nurse, police officer 2000 by Prentice-Hall, Inc 23
Work Sampling - Basic Steps
1. Define the job activities 2. Determine number of observations desired n z e 2 p 1 p where n = sample size z z value for desired confidence level e = degree of error from true mean p = proportion of time spent on activity prior to study
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3. Determine length of sampling period 4. Conduct work sampling study, record observations 5. Periodically re-compute number of observations
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Learning Curve
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Learning Curve
Processing time decreases with worker learning (experience) Time per unit decreases by constant percentage each time output doubles Useful for nonrepetitive, complex jobs requiring requiring long time to complete
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Learning Curve For Mass Production Job
Standard time End of improvement Units produced
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More On Learning Curves
Not effective for mass production jobs Little relative improvement, in a brief time span Product modifications negate effects Productivity improvement can derive from sources besides learning – such as?
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Computing Time For Nth Unit
t n = t 1 n b where t n = time required for nth unit t 1 = time required for first unit n = cumulative number of units produced b = ln r/ln 2, where r is the percentage rate of improvement
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