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8/14/2019 Work Sampling1
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Work Sampling
- MEGHANT NICHANTIndustrial Engineer - IE
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A technique that discovers the proportions
of total time that various activitiescontribute to the job by taking a relativelylarge # of observations at randomintervals
Used to determine: production standards,machine and personnel utilization, and joballowances. Typically faster and cheaperthan other techniques
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Probability based on the binomial distribution
(p + q)n = 1
Mean = np, Variance = npq
As n becomes large, the binomial distribution
approaches the normal distribution
This proportion has distribution of Mean =p,
Variance =pq/n
Theory
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There are many sources of tabulated data for
determining the # of samples required at
various confidence levels and accuracys.
Formula for calculation purposes simplifies
to: n = Z2(1-P)(P)/(L2)
Theory
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A work sampling study requires 95-percent
confidence with five-percent accuracy. How
many observations are required if the machinedown time is eight percent?
n = (1.960)2*(1-0.08)*0.08/(0.05)2
n = 225,76 observations
Example of Sample Size
Calculation
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Sample Size Table
L 0.01 0.05 0.1
N 5644 225.76 56.44
Z=1.96 accuracy at 95% confidence interval,
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Randomized Time of Observation
1st day
1 2 3 4 5
1 30 170 230 20 30
2 150 220 250 170 80
3 160 280 270 260 2404 190 350 280 270 260
5 220 360 290 300 290
6 230 390 350 330 310
7 360 430 480 410 390
8 480 500 530 420 4609 570 560 580 540 480
Data are taken from Random Table(Methods Standards and
Work Design(by Benjamin Niebel and A. Freivalds))
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2nd day
1 2 3 4 5
1 70 60 100 20 50
2 90 100 120 40 70
3 130 160 230 60 90
4 180 350 310 250 2105 200 370 320 320 250
6 220 380 340 330 270
7 240 440 390 340 280
8 290 460 520 370 350
9 570 530 520 380 470
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3rd day
1 2 3 4 5
1 150 20 40 50 50
2 220 30 50 80 90
3 230 60 100 90 220
4 280 100 150 170 280
5 360 130 160 240 310
6 390 210 200 250 340
7 410 300 220 450 360
8 420 330 240 470 440
9 520 560 320 480 450
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4th day 1 2 3 4 5
1 80 40 30 70 50
2 90 90 50 150 60
3 160 90 90 270 90
4 220 130 130 270 1105 330 180 180 280 120
6 440 210 260 300 150
7 460 290 410 310 220
8 540 380 430 380 440
9 560 520 580 490 470
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5th day
1 2 3 4 5
7 20 150 60 80 60
5 40 210 140 100 170
1 100 270 180 130 210
2 280 370 210 130 220
9 280 410 230 150 230
8 310 460 420 230 410
3 340 470 450 340 430
4 360 540 500 430 500
6 470 570 530 570 540
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1st days Work Sampling Summary Sheet
idle
Cla
ssrooms
Flo
or
Ga
rden
WC Labs
Sta
irs
Offices
Posting
Total
Worker1 5 1 2 1 9
Worker2 6 1 1 1 9
Worker3 5 3 1 9
Worker4 7 1 1 9
Worker5 4 1 4 9
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WORKERS DAILY NUTRITION
W3 CONSUMED AV. APPR. CALORIES
CUBE SUGAR 10*2 12*20
NON-ALCOHOLIC DRINKS 2glass/week 41
SNACKS 1 pad 150BREAKFAST .75bread,cheese,olives,jam,sometimes egg 650
LUNCH french fries,rice,soup,salad, 880
sometimes chicken,1 bread
(2 dishes of which is cooked)
DINNER 1 bread,omlette or menemen 750
Total 2126
W4 CONSUMED AV. APPR. CALORIES
CUBE SUGAR 9*2 18*12
NON-ALCOHOLIC DRINKS 1glass/week 20
SNACKS 1pad,1 dessert/week 180
BREAKFAST 1 bread,cheese,olives, jam,sometimes egg 775
LUNCH french fries,rice,soup,salad, 880
sometimes chicken,1 bread
(2 dishes of which is cooked)
DINNER soup,salad,0.5 bread 530
Total 2601
W5(postman) CONSUMED AV. APPR. CALORIES
CUBE SUGAR - -
NON-ALCOHOLIC DRINKS - -
SNACKS - -
BREAKFAST He doesn't have breakfast for years -
LUNCH he eats from cafeteria 850
DINNER chicken,fish,beans,rice 350
(small amounts) Total 1200
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WORKERS' ENERGY CONSUMPTION
(KCAL/MINUTE)
W3 (Heart beat:76)
Floor Cleaning Gardening At rest W.T: 9H 45 M
3.219 2.536 1.485
3.125 2.894 1.176
2.987 2.569 1.205
3.456 2.753 0.857
3.265 2.412 1.025Mean 3.2104 2.6328 1.1496
St. Dev. 0.17362 0.1903069 0.23313
W4 (Heart Beat:72)
Floor Cleaning Gardening At rest W.T: 9H 45 M
3.012 2.154 0.658
2.609 2.423 0.517
3.751 2.036 0.576
2.501 1.956 0.682
2.982 2.125 0.542
Mean 2.971 2.1388 0.595St. Dev. 0.490445 0.1769003 0.072097
W5 postman(Heart Beat:85) W.T: 9H
Posting Lab Res. At rest
5.156 4.856 2.502
5.002 4.256 2.402
4.98 4.987 2.308
5.236 5.123 2.568
5.128 5.236 2.654
Mean 5.1004 4.8916 2.4868
St. Dev. 0.107726 0.3829207 0.13596
WORKERS' OTHER PHYSICAL ACTIVITIES
W3
15 minutes walking for bus stop to go to work 23.5
1-1.5 hours walking for spare times 141
W4
20 minutes walking for bus stop to go to work 26
W530 minutes pysical exercise before sleeping 46
1 hour working for extra time 92
WORKER 3 DAILY CALORY CONSUMPTION
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WORKER 3 DAILY CALORY CONSUMPTION
9H 45M= 585 MINUTES MINUTES CAL.CONS TOTAL CAL.
%56 IDLE 327.6 1.1496 376.6
%33 FLOOR CLEANING 193.05 3.2104 619.8
%11 GARDENING 64.35 2.6328 169.42
1H 45M other activities 105 164.5
12.5 H at home 750 1.1496 862.2
TOTAL 2192.52
WORKER 4 DAILY CALORY CONSUMPTION
9H 45M= 585 MINUTES MINUTES CAL.CONS TOTAL CAL.
%78 IDLE 456.3 0.595 271.5
%11 FLOOR CLEANING 64.35 2.971 191.183%11 GARDENING 64.35 2.1388 137.63
20 M other activities 20 26
13H 55M at home 835 0.595 496.825
TOTAL 1123.14
WORKER 5 DAILY CALORY CONSUMPTION
9H = 540 MINUTES MINUTES CAL.CONS TOTAL CAL.
%44 IDLE 237.6 2.4868 590.863
%45 POSTING 243 5.1004 1239
11% LAB RES. 59.4 4.8916 290.56
30 M exercise 30 46
1 H extra working 60 92
13.5 H at home 810 2.4868 2014.308
TOTAL 4272.73
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PRE-RESULTS
CALORY GAIN CALORI CONSUMPTION
W3 2126 2193
W4 2601 1123
W5 1200 4273
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QUESTIONS AND ANSWERSQUESTIONS AND ANSWERS
CHRISTINE AICKINCHRISTINE AICKIN
`ERGONOMIC ASSESSMENT (Manual Handling)`ERGONOMIC ASSESSMENT (Manual Handling)
OF CLEANING WORK`OF CLEANING WORK`
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Cleaners sustain a high frequency of back, shoulder, neck, arm and
hand injuries. This was verified through a review of Workers'
Compensation statistics, consultation with cleaners and a review of
the literature. What are the factors that build the risk for cleaners
and cleaning in ergonomic means?
Postures required by tasks
Duration and frequency of tasks
Weights handled
Equipment design
Work organization issues
QUESTION 1
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Which suggestions can be made for improvement in the design ofcleaning work, workplace and equipment?
Equipment design and equipment selection Review of equipment prior to purchase, usage of prototypes
Job Design and Work Organisation
Care should be taken that cardiovascular requirements ofcleaning work do not exceed the considered safety level of theworkforce.
Cleaners should be involved in reviewing and planning the waywork is done using their knowledge of cleaning methods,cleaning alms, productivity requirements and health and safetyeffects
Job rotation or job sharing should be practiced where jobswhich have been identified as difficult and are performed forover half an hour
Team work should be performed for heavy works
QUESTION 2
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Education and Trainig
Cleaners should be trained in required job skills as well as team building,
problem solving, occupational health and safety Maintenance and replacement for powered and non-powered
equipment
Improvement of the interface between schools and cleaners
Condition of garbage bins
Condition of classrooms Relationship between cleaners, students and management
Long Term Improvements
Design of the work place (school)
NOTE: Questions & answers are prepared according to Christine AickPaper that has the topic Ergonomic Assessment (Manual Handling)Of Cleaning Work`
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Questions & Comments
Please write us [email protected]
mailto:[email protected]:[email protected]