Work Study in Operations managment

Work study is the sys­tem­atic exam­i­na­tion of how a job is done, car­ried out to find a bet­ter method and to fix the right time that a qual­i­fied worker should take to do it. Its pur­pose is to raise pro­duc­tiv­ity by mak­ing bet­ter use of peo­ple, machines, mate­ri­als and space, usu­ally with­out large new invest­ment.

Think of a worker pack­ing books into car­tons. If the books are kept far away, the tape is often miss­ing and the worker bends again and again, the job is slow and tir­ing. Place the books within reach, keep the tape in a fixed spot, set the table at the right height and arrange the steps in a sen­si­ble order, and the same job becomes faster and eas­ier. Study­ing a job in this organ­ised way, improv­ing it and then set­ting a fair time for it is work study. The approach grew out of the sci­en­tific man­age­ment move­ment of F. W. Tay­lor (time study) and Frank and Lil­lian Gilbreth (motion study) in the early twen­ti­eth cen­tury.

Objec­tives and impor­tance of work study

The main objec­tive of work study is to increase pro­duc­tiv­ity by improv­ing the method of work and by set­ting proper time stan­dards. It there­fore answers two ques­tions: what is the best way to do this job, and how long should it nor­mally take?

Why organ­i­sa­tions use it

• more out­put from the same resources
• less waste of mate­r­ial, move­ment and machine time
• less worker fatigue and bet­ter safety
• lower cost per unit
• bet­ter use of time, and accu­rate data for plan­ning
• stan­dard­ised, bet­ter meth­ods of work­ing

What hap­pens with­out it

When work is not stud­ied, work­ers make unnec­es­sary motions, jobs take longer than they need to, machines wait for mate­r­ial, pro­duc­tion cost rises and pro­duc­tiv­ity stays low. Man­age­ment is left to plan by guess­work. Work study replaces that guess­work with obser­va­tion, data and mea­sur­able stan­dards.

The two parts of work study

Work study has two com­ple­men­tary parts, and this is the most impor­tant point of the whole topic.

• Method study is the sys­tem­atic record­ing and crit­i­cal exam­i­na­tion of the exist­ing and pro­posed ways of doing work, in order to develop eas­ier and more effec­tive meth­ods and reduce costs. In short, it finds the best way.
• Work mea­sure­ment is the appli­ca­tion of tech­niques to estab­lish the time for a qual­i­fied worker to carry out a spec­i­fied job at a defined level of per­for­mance. In short, it finds the right time.

The order mat­ters. Method study nor­mally comes first, because there is lit­tle value in mea­sur­ing the time of a poor method with great accu­racy. Once the method is improved and stan­dard­ised, work mea­sure­ment sets the time stan­dard for it.

Method study in brief

Method study is the care­ful analy­sis of the present method so that a bet­ter one can be devel­oped. It asks whether the work can be done more sim­ply, whether steps can be removed, whether move­ment can be reduced, whether tools can be rearranged and whether fatigue can be cut. It is used to elim­i­nate unnec­es­sary oper­a­tions, improve the flow of work, sim­plify the job, lower cost and improve qual­ity and safety.

For exam­ple, if a worker has to walk to fetch mate­r­ial, bring it back, search for a tool and then return for another item, method study may sug­gest keep­ing mate­r­ial near the worker, keep­ing tools in fixed posi­tions, chang­ing the sequence of steps and improv­ing the table arrange­ment.

Steps in method study

1. Select the job that most needs improve­ment (high cost, fre­quent delay, exces­sive move­ment, safety prob­lems).
2. Record all rel­e­vant facts about the present method, gath­er­ing enough data of good qual­ity to serve as the basis for exam­i­na­tion. Process charts and dia­grams are used here.
3. Exam­ine each step crit­i­cally by ask­ing what is done, why, where, when, who does it and how.
4. Develop the most prac­ti­cal, eco­nom­i­cal and safe method.
5. Install the new method: train work­ers, rearrange the work­place and issue instruc­tions.
6. Main­tain the method by check­ing reg­u­larly that it con­tin­ues to be fol­lowed.

Some text­books add a Define step (write down the new method as a stan­dard prac­tice) and an Eval­u­ate step (com­pare results with the old method). The detailed treat­ment is in the sep­a­rate arti­cle on method study.

Motion study and therbligs

Motion study exam­ines the body move­ments used in a task in order to remove use­less motions, reduce fatigue and improve the arrange­ment of the work­place. Frank Gilbreth broke man­ual work into basic motion ele­ments called therbligs (roughly "Gilbreth" spelt back­wards). Exam­ples are search, select, grasp, reach (trans­port empty), move (trans­port loaded), hold, release load, posi­tion, inspect, and delays such as unavoid­able delay and rest. When therbligs are stud­ied frame by frame from film or video, the tech­nique is called micro­mo­tion study. Motion study is nar­rower than work study: it deals with the move­ments inside a method, not with the time stan­dard.

Work mea­sure­ment in brief

Work mea­sure­ment tells man­age­ment the stan­dard time for a job: the time allowed for a qual­i­fied worker, work­ing at a nor­mal pace under stated con­di­tions, includ­ing allowances for rest and per­sonal needs. With­out it, man­age­ment does not know how long a job should take, whether a worker is slow or the method is poor, or how to plan wages, sched­ules and capac­ity.

Uses of work mea­sure­ment

• fix­ing stan­dard time and out­put tar­gets
• man­power plan­ning and capac­ity plan­ning
• pro­duc­tion sched­ul­ing and deliv­ery promises
• labour cost esti­ma­tion and pric­ing
• com­par­ing pro­duc­tiv­ity across work­ers, shifts or plants
• design­ing fair wage incen­tive schemes

Tech­niques of work mea­sure­ment

Time study

Time study is the tech­nique of record­ing the times and rates of work­ing for the ele­ments of a spec­i­fied job, and analysing the data to obtain the time needed to do the job at a defined level of per­for­mance. The job is bro­ken into ele­ments (for pack­ing: pick the prod­uct, place it in the box, seal, label), each ele­ment is timed over sev­eral cycles, the aver­age is adjusted by a per­for­mance rat­ing, and allowances are added. The core for­mu­las are:

$$\displaystyle \text{Normal time} = \text{Observed time} \times \frac{\text{Rating}}{100}$$

$$\text{Standard time} = \text{Normal time} \times (1 + \text{allowance fraction})$$

Work sam­pling

Instead of tim­ing a job con­tin­u­ously, the observer checks at ran­dom moments: is the worker work­ing, is the worker wait­ing, is the machine idle, is a set-up under way? If 340 of 400 ran­dom obser­va­tions find a machine run­ning, the machine is esti­mated to be busy $\displaystyle \frac{340}{400} = 0.85$, or 85 per cent, of the time. Work sam­pling suits long jobs, many work­ers or machines, and sit­u­a­tions where con­tin­u­ous tim­ing is imprac­ti­cal.

Worked exam­ple: mea­sur­ing the gain from work study

Sup­pose a ware­house pack­ing sta­tion (hypo­thet­i­cal fig­ures) packs 100 boxes per hour. The ana­lyst finds that the packer walks to a far rack for car­tons, the tape dis­penser is on another table and both hands are rarely used together. After method study the car­tons are placed within reach, the tape is fixed to the bench and the sequence is changed. Out­put rises to 130 boxes per hour. The packer is paid ₹160 per hour.

Step 1: labour pro­duc­tiv­ity. Before: 100 boxes per labour-hour. After: 130 boxes per labour-hour.

Step 2: per­cent­age improve­ment.

$$\displaystyle \text{Improvement} = \frac{130 - 100}{100} \times 100 = 30\%$$

Step 3: labour cost per box.

$$\displaystyle \text{Before} = \frac{160}{100} = 1.60 \qquad \text{After} = \frac{160}{130} = 1.2308 \approx 1.23$$

So labour cost falls from ₹1.60 to about ₹1.23 per box, a sav­ing of about ₹0.37 per box.

Step 4: sav­ing per shift. In an 8-hour shift the sta­tion now packs $8 \times 130 = 1{,}040$ boxes. Packed the old way, those boxes would have cost $1{,}040 \times 1.60 = 1{,}664$ rupees in labour; they now cost $8 \times 160 = 1{,}280$ rupees. The sav­ing is ₹384 per shift.

Step 5: a new stan­dard time. A time study of the improved method gives an observed time of 0.42 minute per box for a worker rated at 105 per cent, with allowances of 10 per cent:

$$\text{Normal time} = 0.42 \times 1.05 = 0.441 \text{ min}$$

$$\text{Standard time} = 0.441 \times 1.10 = 0.4851 \text{ min} \approx 0.485 \text{ min}$$

The stan­dard out­put is there­fore $\displaystyle \frac{60}{0.4851} \approx 123.7$, or about 123 boxes per hour. The mea­sured 130 boxes per hour is a good work­er's pace; the stan­dard of about 123 is what plan­ners should assume for a nor­mal worker once rest is included.

Ben­e­fits of work study

Bet­ter use of resources and higher pro­duc­tiv­ity

Peo­ple, machines and mate­ri­als are used more effec­tively, and out­put can rise with­out adding resources.

Lower cost

Bet­ter meth­ods and proper time stan­dards remove waste and inef­fi­ciency.

Bet­ter plan­ning and con­trol

Man­age­ment gets reli­able time data for sched­ul­ing, cost­ing, pric­ing and deliv­ery promises.

Less fatigue and bet­ter safety

Improved motions and lay­outs remove awk­ward reaches, bend­ing and need­less walk­ing, which also reduces acci­dent risk.

Fair wages and incen­tives

Mea­sured stan­dards give an objec­tive basis for incen­tive schemes, so extra pay is linked to gen­uine extra out­put.

Work study in ser­vices

Work study is not con­fined to fac­to­ries. Hos­pi­tals use it to speed up the move­ment of patient files and reduce wait­ing; banks use it to cut the steps in account open­ing and reduce cus­tomer queues; offices use it to sim­plify form pro­cess­ing; retail stores use it to design billing coun­ters; ware­houses use it to improve pick­ing and pack­ing; schools and col­leges use it to stream­line admis­sions. Wher­ever a task is repeated, it can be stud­ied and improved.

Prob­lems and con­di­tions for suc­cess

Com­mon prob­lems

• Worker resis­tance: work­ers may feel watched and fear higher tar­gets or job losses.
• Inac­cu­rate obser­va­tion: care­less record­ing or too few cycles gives weak results.
• Unnat­ural behav­iour: peo­ple may speed up or slow down while being observed.
• Poor coop­er­a­tion: with­out sup­port from super­vi­sors and unions, changes are not adopted.
• Chang­ing con­di­tions: when tools, lay­out or prod­uct design change, stan­dards become out of date.

Con­di­tions for suc­cess

• vis­i­ble sup­port from top man­age­ment
• open com­mu­ni­ca­tion and worker par­tic­i­pa­tion, with an assur­ance that gains will be shared
• trained, impar­tial ana­lysts
• a clear def­i­n­i­tion of the job and method before tim­ing
• prac­ti­cal improve­ments rather than the­o­ret­i­cal ones
• reg­u­lar review of meth­ods and stan­dards

Work study should be pre­sented as a tool for improv­ing the work, not for crit­i­cis­ing the worker.

Dis­tin­guish­ing related terms

Work study is one of the core tools of indus­trial engi­neer­ing and oper­a­tions man­age­ment because it improves sys­tems through obser­va­tion, data, analy­sis and stan­dard­i­s­a­tion.

Key terms

Work study

The sys­tem­atic exam­i­na­tion of meth­ods of doing work, and the mea­sure­ment of the time needed, to improve pro­duc­tiv­ity.

Method study

Record­ing and crit­i­cally exam­in­ing exist­ing and pro­posed ways of doing work to develop eas­ier, more effec­tive meth­ods.

Work mea­sure­ment

Tech­niques for estab­lish­ing the time a qual­i­fied worker needs for a spec­i­fied job at a defined level of per­for­mance.

Stan­dard time

Nor­mal time plus allowances; the time allowed for a job for plan­ning, cost­ing and incen­tives.

Per­for­mance rat­ing

The ana­lyst's judge­ment of a work­er's pace com­pared with a defined nor­mal pace, expressed as a per­cent­age.

Allowances

Extra time added to nor­mal time for per­sonal needs, fatigue and unavoid­able delays.

Therblig

One of the basic motion ele­ments, such as grasp, reach or release, iden­ti­fied by Gilbreth.

Work sam­pling

Esti­mat­ing the share of time spent on dif­fer­ent activ­i­ties from many ran­dom obser­va­tions.

Qual­i­fied worker

A worker with the phys­i­cal attrib­utes, skill and knowl­edge to do the job to the required stan­dard.

Com­mon ques­tions

Why is method study done before work mea­sure­ment?

Because a time stan­dard is only as good as the method it mea­sures. If a waste­ful method is timed, the waste is built into the stan­dard. The method is improved and fixed first, and then its time is mea­sured.

Is time study the same as work study?

No. Work study is the broad field that includes method study and work mea­sure­ment. Time study is one tech­nique of work mea­sure­ment.

How does work study increase pro­duc­tiv­ity with­out new machines?

It removes unnec­es­sary steps, move­ment and wait­ing, so the same worker and equip­ment pro­duce more out­put in the same time. In the exam­ple above, out­put rose from 100 to 130 boxes per hour with the same packer and bench.

When should work sam­pling be used instead of time study?

When work is long, irreg­u­lar or spread across many peo­ple or machines, or when the aim is to find the share of idle time or machine util­i­sa­tion rather than the time for one repet­i­tive cycle.

Why do work­ers some­times resist work study?

They may fear tighter tar­gets, reduced earn­ings or job losses, and dis­like being watched. Explain­ing the pur­pose, involv­ing work­ers in find­ing improve­ments and shar­ing the gains reduces resis­tance.

Ref­er­ences

1. Kanawaty, G. (ed.) Intro­duc­tion to Work Study. Inter­na­tional Labour Office, Geneva.
2. Tay­lor, F. W. (1911) The Prin­ci­ples of Sci­en­tific Man­age­ment. Harper & Broth­ers.
3. Gilbreth, F. B. (1911) Motion Study. D. Van Nos­trand Com­pany.
4. Steven­son, W. J. Oper­a­tions Man­age­ment. McGraw-Hill Edu­ca­tion.
5. Pan­neer­sel­vam, R. Pro­duc­tion and Oper­a­tions Man­age­ment. PHI Learn­ing.

Related read­ing

• MRP in Oper­a­tions Man­age­ment (Mate­r­ial Require­ments Plan­ning)
• Method Study in Oper­a­tions Man­age­ment
• Time Study and Work Mea­sure­ment in Oper­a­tions Man­age­ment