Work Sampling1

Work Sampling - MEGHANT NICHANT Industrial Engineer - IE

• A technique that discovers the proportions of total time that various activities contribute to the job by taking a relatively large # of observations at random intervals • Used to determine: production standards, machine and personnel utilization, and job allowances. Typically faster and cheaper than other techniques

Theory • 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 • There are many sources of tabulated data for determining the # of samples required at various confidence levels and accuracy’s. • Formula for calculation purposes simplifies to: n = Z2(1-P)(P)/(L2)

Example of Sample Size Calculation • A work sampling study requires 95-percent confidence with five-percent accuracy. How many observations are required if the machine down time is eight percent? – n = (1.960)2*(1-0.08)*0.08/(0.05)2 – n = 225,76 observations

Sample Size Table Z=1.96 accuracy at 95% confidence interval,

L N

0.01 5644

0.05 225.76

0.1 56.44

Randomized Time of Observation 1st day 1 2 3 4 5 6 7 8 9

1 30 150 160 190 220 230 360 480 570

2 170 220 280 350 360 390 430 500 560

3 230 250 270 280 290 350 480 530 580

4 20 170 260 270 300 330 410 420 540

5 30 80 240 260 290 310 390 460 480

Data are taken from Random Table(Methods Standards and Work Design(by Benjamin Niebel and A. Freivalds))

2nd day 1 2 3 4 5 6 7 8 9

1 70 90 130 180 200 220 240 290 570

2 60 100 160 350 370 380 440 460 530

3 100 120 230 310 320 340 390 520 520

4 20 40 60 250 320 330 340 370 380

5 50 70 90 210 250 270 280 350 470

3rd day 1 2 3 4 5 6 7 8 9

1 150 220 230 280 360 390 410 420 520

2 20 30 60 100 130 210 300 330 560

3 40 50 100 150 160 200 220 240 320

4 50 80 90 170 240 250 450 470 480

5 50 90 220 280 310 340 360 440 450

4th day 1 2 3 4 5 6 7 8 9

1 80 90 160 220 330 440 460 540 560

2 40 90 90 130 180 210 290 380 520

3 30 50 90 130 180 260 410 430 580

4 70 150 270 270 280 300 310 380 490

5 50 60 90 110 120 150 220 440 470

5th day 7 5 1 2 9 8 3 4 6

1 20 40 100 280 280 310 340 360 470

2 150 210 270 370 410 460 470 540 570

3 60 140 180 210 230 420 450 500 530

4 80 100 130 130 150 230 340 430 570

5 60 170 210 220 230 410 430 500 540

2 1

Offices

Stairs

Labs

WC

Garden

Floor 1 1 3 1

Total

5 6 5 7 4

Posting

Worker1 Worker2 Worker3 Worker4 Worker5

Classrooms

idle

1st day’s Work Sampling Summary Sheet

4

9 9 9 9 9

1 1

1 1 1

WORKERS DAILY NUTRITION W3

CONSUMED

CUBE SUGAR NON-ALCOHOLIC DRINKS SNACKS BREAKFAST LUNCH

10*2 2glass/week 1 pad .75bread,cheese,olives,jam,sometimes egg french fries,rice,soup,salad, sometimes chicken,1 bread (2 dishes of which is cooked) 1 bread,omlette or menemen Total

DINNER

W4

CONSUMED

CUBE SUGAR NON-ALCOHOLIC DRINKS SNACKS BREAKFAST LUNCH

9*2 1glass/week 1pad,1 dessert/week 1 bread,cheese,olives,jam,sometimes egg french fries,rice,soup,salad, sometimes chicken,1 bread (2 dishes of which is cooked) soup,salad,0.5 bread Total

DINNER

W5(postman)

CONSUMED

CUBE SUGAR NON-ALCOHOLIC DRINKS SNACKS BREAKFAST LUNCH DINNER

He doesn't have breakfast for years he eats from cafeteria chicken,fish,beans,rice (small amounts) Total

AV. APPR. CALORIES 12*20 41 150 650 880

750 2126 AV. APPR. CALORIES 18*12 20 180 775 880

530 2601 AV. APPR. CALORIES 850 350 1200

WORKERS' ENERGY CONSUMPTION (KCAL/MINUTE)

W3 (Heart beat:76) Floor Cleaning 3.219 3.125 2.987 3.456 3.265 Mean 3.2104 St. Dev. 0.17362

Gardening 2.536 2.894 2.569 2.753 2.412 2.6328 0.1903069

At rest 1.485 1.176 1.205 0.857 1.025 1.1496 0.23313

W.T: 9H 45 M

W4 (Heart Beat:72) Floor Cleaning 3.012 2.609 3.751 2.501 2.982 Mean 2.971 St. Dev. 0.490445

Gardening 2.154 2.423 2.036 1.956 2.125 2.1388 0.1769003

At rest 0.658 0.517 0.576 0.682 0.542 0.595 0.072097

W.T: 9H 45 M

W5 postman(Heart Beat:85) Posting 5.156 5.002 4.98 5.236 5.128 Mean 5.1004 St. Dev. 0.107726

Lab Res. 4.856 4.256 4.987 5.123 5.236 4.8916 0.3829207

W.T: 9H At rest 2.502 2.402 2.308 2.568 2.654 2.4868 0.13596

WORKERS' OTHER PHYSICAL ACTIVITIES W3 15 minutes walking for bus stop to go to work 1-1.5 hours walking for spare times

23.5 141

W4 20 minutes walking for bus stop to go to work

26

W5 30 minutes pysical exercise before sleeping 1 hour working for extra time

46 92

WORKER 3 DAILY CALORY CONSUMPTION 9H 45M= 585 MINUTES %56 IDLE %33 FLOOR CLEANING %11 GARDENING 1H 45M other activities 12.5 H at home

MINUTES

CAL.CONS TOTAL CAL.

327.6 193.05 64.35

1.1496 3.2104 2.6328

376.6 619.8 169.42

105 750

1.1496

164.5 862.2

TOTAL

2192.52

WORKER 4 DAILY CALORY CONSUMPTION 9H 45M= 585 MINUTES %78 IDLE %11 FLOOR CLEANING %11 GARDENING 20 M other activities 13H 55M at home

MINUTES

CAL.CONS TOTAL CAL.

456.3 64.35 64.35

0.595 2.971 2.1388

271.5 191.183 137.63

20 835

0.595

26 496.825

TOTAL

1123.14

WORKER 5 DAILY CALORY CONSUMPTION 9H = 540 MINUTES %44 IDLE %45 POSTING 11% LAB RES. 30 M exercise 1 H extra working 13.5 H at home

MINUTES 237.6 243 59.4 30 60 810

CAL.CONS TOTAL CAL. 2.4868 5.1004 4.8916

590.863 1239 290.56

46 92 2.4868 2014.308 TOTAL

4272.73

PRE-RESULTS CALORY GAIN

CALORI CONSUMPTION

W3

2126

2193

W4

2601

1123

W5

1200

4273

QUESTIONS AND ANSWERS CHRISTINE AICKIN `ERGONOMIC ASSESSMENT (Manual Handling) OF CLEANING WORK`

QUESTION 1

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 2 Which suggestions can be made for improvement in the design of ‘cleaning’ 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 of cleaning work do not exceed the considered safety level of the workforce. Cleaners should be involved in reviewing and planning the way work is done using their knowledge of cleaning methods, cleaning alms, productivity requirements and health and safety effects Job rotation or job sharing should be practiced where jobs which have been identified as difficult and are performed for over half an hour Team work should be performed for heavy works

•

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 Aicki Paper that has the topic `Ergonomic Assessment (Manual Handling) Of Cleaning Work`

Questions & Comments Please write us on [email protected]