Work Measurement & StandardsApplied Management Science for Decision Making, 1e 2012 Pearson Prentice-Hall, Inc. Philip A. Vaccaro , PhD

Micro-Approach School of Job Design In 1820s England, the first efforts to cut costs and increase productivity began.

Frederick Winslow Taylor ( 1881 ) organized the research findings and developed more formal methods.

He is considered to be the Father of Scientific Management. THE TAYLOR SCHOOL / THE TECHNICAL - PHYSICAL SCHOOL

Taylor School of Job DesignEliminate idle time for workers and machines.

Eliminate duplication of effort.

Streamline the flow of work through the firm.

Rearrange task sequences for more efficiency.

Reduce jobs to short-cycle , repetitive ones for higher productivity and eventual replacement of humans with machines.

Systematic reduction of skill requirements in each job.

ASSUMES WORKERS SOLE MOTIVATION IS MORE MONEYTENETS

Work Measurement & TimeStandards

Direct Time Study

Predetermined Time Study

Work Sampling Performance Ratings Allowance Factors Sample Size Determination Observation Schedules Interpretation of Findings Sample Size Determination Therbligs The MTM Product

Direct Time StudyEXAMPLEProblem Statement

Twenty workers who perform the identical job are selected forthis time study. Each worker will be timed over five (5) cycles.Assume that the total observed time will eventually equal 400 minutes.

Requirement

Develop a time standard for a particular worker.THE WORKER SAMPLE CAN BESELECTED FROM A SINGLE FACILITYOR IT MAY BE A COMPOSITE SAMPLE SELECTED FROMSEVERAL FACILITIES

Direct Time StudyEXAMPLE1. COMPUTE THE OBSERVED TIMEOT = SUM OF ALL OBSERVED TIMESNUMBER OF OBSERVED CYCLES= 400 MINUTES100 CYCLES= 4.000 MINUTESOBSERVED TIME IS COMPUTED THREE PLACES TO THE RIGHT OF THE DECIMAL POINTakaAverageCycleTime

Direct Time StudyEXAMPLE2. COMPUTE THE NORMAL TIMENT = OT x PRTHE PERFORMANCE RATING ADJUSTS THE OBSERVED TIME TO WHAT THE NORMAL TIMESHOULD BE FOR A PARTICULAR WORKER.

EVERY WORKER IS ASSIGNED A UNIQUE PERFORMANCE RATING BY THE TIME AND MOTIONANALYST.*

Performance Ratings PR = 1.0 denotes an average worker.

PR < 1.0 denotes a fast worker.

PR > 1.0 denotes a slow worker.PERFORMANCE RATINGS ARE ESTABLISHED FOR EACH WORKER.IT IS STILL SOMETHING OF AN ART AND CONSEQUENTLY CAN BECHALLENGED BY UNION OFFICIALS. THOROUGH DOCUMENTATION OF ALL PERFORMANCE RATINGS IS ESSENTIAL.

Direct Time Study2. NORMAL TIME ( continued ) A particular worker in this time study has been assigned a performance rating of 85% .

This means s/he has been judged to be a fast worker and thus should be held to a bit shorter normal time , or higher level of performance.NT = ( 4.000 ) x ( .85 ) = 3.400 MINUTES

Direct Time StudyEXAMPLE3. COMPUTE THE STANDARD TIMEST = NT1 - AFNT + [ AF x OT ]*** THE ALLOWANCE FACTOR IS ASSIGNED TO ALL WORKERS PERFORMING THEIDENTICAL TASK. IT INCLUDES EXTRA TIME FOR PERSONAL NEEDS, FATIGUE,RECURRING AND UNAVOIDABLE WORK DELAYS, AND CLEANUP BETWEENVARIOUS OPERATIONS

Allowance Factors Constant Allowances PERSONAL5% FATIGUE....4% Variable Allowances STANDING.2 to 4% MENTAL STRAIN.4 to 8% TEDIOUSNESS.2 to 5% NOISE LEVEL...2 to 5% HEAT / HUMIDITY0 to 10% POOR LIGHTING..2 to 5%EXAMPLE

Direct Time StudyEXAMPLE ASSUME AN ALLOWANCE FACTOR OF 13% WITH THE CHOICE OF FORMULA LEFT TO THE DISCRETION OF THE ANALYST.3. COMPUTE THE STANDARD TIME ( continued )ST = 3.4001 - .13=3.400.87=3.900 MINUTESST = 3.400 + [.13 x 4.000] = 3.400 + .5200 = 3.920 MINUTES

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Work MeasurementandStandard Setting

For simplicity, we assume that each of the five workers observed had an actual performance time of 4 minutes

The particular worker that we are setting a standardfor, has a performance rating of 85%This worker performs a short cycle job with onlyone (1) particular activity or element involved

Average cycle time or OT ( observed time ) = 4.0 minutes

Normal time ( OT x PR ) = ( 4.00 x .85 ) = 3.4 minutes

Standard time = [ NT / ( 1 - AF ) ] = [ 3.4 / ( 1 - .13 ) ] = 3.91 minutes

Direct Time StudySAMPLE SIZE DETERMINATIONSuppose we want to know the number of cycles we must observe in order to obtainan average cycle time that is 95% certain to fall within +/- 5% of the actual averagecycle time for all workers performing thisjob or task within a job.

Direct Time StudySAMPLE SIZE DETERMINATIONLets say you did a pilot time study in whichsix workers performing the identical job ortask were observed over two cycles eachfor a total of twelve cyclesAverage cycle time for this sample turnedout to be 3.000 minutes with a standarddeviation of 1.000 minutex = 3.000s = 1.000_

Direct Time StudySAMPLE SIZE DETERMINATIONTHE FORMULAn = z s x2where:x = THE SAMPLE MEANs = THE SAMPLE STANDARD DEVIATION = ALLOWABLE OR TOLERATED ERROR EXPRESSED AS A DECIMAL ( 5% = .05 )z = NUMBER OF STANDARD DEVIATIONS FOR THE DESIRED CONFIDENCE LEVEL ( 95% = 1.96 )

_

Direct Time StudySAMPLE SIZE DETERMINATIONn = 1.96 x 1.02.05 x 3.0=1.96.15213.062=171

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Sample SizeDetermination

Direct Time StudyADDITIONAL COMMENTS When observed times are not consistent, they need to be reviewed. Abnormally short or long times may be the result of an observational error and are usually discarded.

Normal times (NT) are sometimes computed for each element of a job because the performance rating may vary for each element. In other words, the same worker may be fast on some tasks but slow or average on other tasks.

Intra - Job Performance RatingsEXAMPLEA MUCH MORE ACCURATESTANDARD SETTINGPROCEDURE !

Job ElementPerformance RatingDrawing Materials0.99Assembling Parts1.08Product Coating0.83Product Inspection1.20

Predetermined Time StandardsRoutine, repetitive jobs are divided into basic motions

of the human body.

These motions have been studied under numerous conditions and assigned specific times.

A time standard for a particular job is found by adding these basic motion times together.

Predetermined Time StandardsTHERBLIGS Basic or elemental motions of the human body are called therbligs

Term was coined by Frank Gilbreth

They include such activities as select, grasp, position, assemble, reach, hold, and inspect

Time values for therbligs are specified in very detailed tables*GILBRETH SPELLED BACKWARDS WITH T AND H TRANSPOSED

Predetermined Time StandardsTHERBLIGS: ELEMENTAL MOTIONS OF THE HUMAN BODYONE OF THE FIRST JOBS STUDIED WAS THAT OF THE STOKER

KNEESHEADARMSTORSOLEGSELBOWSFEET

Frank & Lillian Gilbreth Colleagues of Frederick Taylor

Among the first to systematically seek the best way to perform jobs

They used clocks, still cameras, and movie cameras to record the movements of workers while they performed their jobs

Their family was the basis for the movie Cheaper by the Dozen. 1950&1995

The Gilbreth FamilyPHOTOGRAPH TAKEN AT THEIR MONTCLAIR, NEW JERSEY HOME

Predetermined Time StandardsTHERBLIG TIME MEASUREMENT Stated in terms of time measurement units or TMUs

One TMU equals .00001 hours

One TMU equals .0006 minutes

There are 100,000 TMUs in one hour

Predetermined Time StandardsMethods Time Measurement

is a product of the MTM Association, Fairlawn, New Jersey 07410.

It is a family of products including MTM-C which deals with clerical tasks, and MTM-HC which deals with healthcare industry tasks.

Provides a comprehensive system of predetermined time standards which would be prohibitively expensive for a single firm to develop.

Services include consulting, data base rental, and custom performance standards for one or more jobs set by MTM professional staff.

MTM ASSOCIATION MTM IS A COPYRIGHTED PRODUCT

Predetermined Time StudyUSING THE MTM SYSTEM TO DEVELOP A TIMEThe most complex motion or therbligin the MTM system is get and place . We must know four things:What is to be gotten.Its approximate weight.Where it must be placed.How far it must be moved.

Predetermined Time StudyDEVELOPING A TIME FOR GET AND PLACEThe conditions for getting a unit and placing it before the worker are: A part is needed for assembly.Its weight is less than 2 pounds.It must be moved to the workers

immediate front.It must be moved between 8 and

20 inches from the far corner of a work table.

Predetermined Time Study

Each Part< 2 lbsWorkBenchStandingWorker 8 to 20 inches GET AND PLACE EXAMPLE

Predetermined Time StudySAMPLE MTM TABLE FOR GET AND PLACEDistanceIn Inches< 8> 8< 20> 20< 32Weight ( lbs. ) GET Conditions PLACE AccuracyCode123ApproxAA203550

Predetermined Time StudyDEVELOPING A TIME FOR GET AND PLACEAdditional Weight Categories ( not shown ) > 2 pounds < 18 pounds

> 18 pounds < 45 poundsAdditional Conditions of Get ( not shown )Difficult

HandfulOF COURSE THE MTM THERBLIGS FOR THESE CONDITIONS WOULD HAVE DIFFERENT CODES SUCH AS AD2, AE3

Predetermined Time StudyCOMPLETE MTM JOB TIME EXAMPLEAssemble the two Items Inspect the assemblyPlace the assemblyin a boxAA2AC2AD2PT1

GB3.0006 x 258 = .1548 STANDARD MINUTES FOR THIS COMPLETE JOB

JOB ELEMENT( THERBLIG )JOB ELEMENTCODEJOB ELEMENT TIME( in TMUs )Draw item A from left corner of table35Draw item B from right corner of table55458340 TMUs258

Predetermined Time Study2nd EXAMPLE Suppose there are 8 therbligs in a short-cycle, repetitive job

Suppose the sum of the therblig TMUs = 397.9

Since each TMU = .036 seconds, this jobs cycle time equals 14.32 seconds ( 397.9 x .036 )

14.32 seconds = .23838 minutes ( 14.32 / 60 )

251.7 cycles of this job should be expected each hour by management ( 60 / .23838 )

Standard hourly output would therefore be 252 units

Predetermined Time StudyDoes not disrupt the actual production operation.

No performance ratings are necessary.

No allowance factors are necessary.

Unions tend to accept it as fair.Particularly effective in firms that employ many workers performing similar tasks, i.e. it is cost-effective.

Can be used for planning purposes because the time standard can be set before the job actually exists!ADVANTAGES

Work SamplingDeveloped in England in the 1930s by Leonard Tippet

Estimates the percentage of time that a worker spends on various tasks.

Random observations are used to record employee activity.

The only technique available for measuring and evaluating non-repetitive jobs.The Most UsedTechnique in theService Sector

Leonard Henry Caleb Tippett1902 - 1985English physicist and statisticianwho used what he called asnap reading method to obtain,at random time intervals, observationsof textile machine operators forthe purpose of estimating thepercentage of time spent on theirduties. L.H.C. Tippett

Leonard Henry Caleb Tippett Awarded the Walter Shewart Medal of the American Society for Quality Control

Awarded the Warner Medal of the Textile Institute for improving the production efficiency and operative utilization of the textile industry

Educated at Imperial College, and University College, London

President of the Royal Statistical Society, 1965

Shirley Institute, Manchester, England, 1925-19651902 - 1985

Work Sampling Applications Establishing labor and production standards.

Discovering how employees allocate their time for both work and non-work activity.

Providing the basis for staffing changes, job training, reassignments of duties, hiring, and termination.

Work Sampling In ActionThe mail order catalogerLands End expects itscall center representativesto be busy 85% of the timeWhen the busy ratio hits90% , the firm believes it isnot attaining its set goalof high quality serviceThe firm then plansto hire more representativesto restore the desiredlevel of service

Work SamplingSIX RANDOM VISITS TO JOES OFFICEJOEBOSSEXPECT TOSEE THISANDMORE !

Monday 10:30 amFlying paper airplanesWednesday 2:20 pmWatching TVThursday 9:45 amReading Sports PageThursday 1:25 pmBuying Cruise Tickets On-LineFriday 2:30 pmDoing Homework for Night SchoolFriday 4:30 pmLeft Early

Work Sampling ProcedureTake a preliminary sample to obtain an estimate

of a parameter value such as the percentage of time a worker is busy.

Compute the sample size required for the formal

work sampling study.

Prepare a worker observation schedule.

Observe and record worker activities.

Determine how workers are spending their time.

Work Sampling ExampleThe REGISTRY of MOTOR VEHICLESThe manager of a branch officeestimates that her employeesare idle 25% of the time. Shewants to confirm or disprove this by taking a work samplethat is accurate to within +/- 3% and yields a 95% confidence

Sample Size Computation Formula z x p x q22where:n = required sample size

z = standard normal deviate for the desired confidence level

p = estimated value of the sample proportion ( of time worker is busy )

q = estimated value of the sample proportion ( of time worker is idle )

= acceptable error level ( in percent )n =

Sample Size Computationn = (2) x (.25)(.75)(.03)= 8332295% CONFIDENCE LEVEL ( z )3 PERCENT TOLERATED ERROR ( )75% BUSY PROPORTION ( q )25% IDLE PROPORTION ( p )WORK SAMPLINGWE COULD HAVE DESIGNATED THE BUSY PROPORTION p AND THE IDLE PROPORTION q

Work Sampling ExampleThe REGISTRYof MOTOR VEHICLESUtilizing the sample size formula,she finds that 833 observationsshould be taken. If the percentageof idle time observed is not closeto 25% as the study progresses,the number of observations mayneed to be recomputed and raisedas appropriate.

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Work Sampling

Work Sampling ResultsThe REGISTRY of MOTOR VEHICLESNOT WORKRELATED

Number of ObservationsActivity485on phone / meeting clients126idle62personal time23supervisor meetings137filing, data entry = 833

Work Sampling ConclusionThe REGISTRY of MOTOR VEHICLES All but 188 of the observations are work-related.

Since 22.6% is less idle time than the branch manager believes necessary to ensure a high client service level, she needs to find a way to reduce current work loads.

This could be accomplished via a reassignment of duties or the hiring of additional personnel.( 126 IDLE & 62 PERSONAL )( 188 / 833 = 22% )

Employee Observation SchedulePREPARATIONEXAMPLEDraw five random numbers from a table:

07 12 22 25 49These random numbers can then be usedto create an observation schedule:

9:07 9:12 9:22 9:25 9:49RANDOM NUMBERS ARE USED TO GENERATE THE VISITATION SCHEDULE9:07 - JOE9:12 - BOB9:22 - CAROL9:25 - TIM9:49 - JOAN

Employee Observation ScheduleCOMMENTS Observations are to be made in a non-intrusive manner so as not to distort employee normal work patterns.

Observations are to be made in a random and unbiased manner over a period of 2 weeks in order to ensure a valid sample.

Activities that constitute work must be clearly defined such as filing, data entry, meetings, and writing reports.

Work Sampling ResultsTYPICAL MANUFACTURING SITUATION

PRODUCTIVE WORK75%IDLE TIME BETWEEN TASKS..9%BREAKS AND LUNCH7%DOWNTIME & UNSCHEDULED TASKS.4%CLEANUP......3%START- UP.2%

Work SamplingLESS EXPENSIVE

NO TIMING DEVICES

LITTLE TRAINING NEEDED

STUDY CAN BE DELAYED TEMPORARILY WITH LITTLE IMPACT ON THE RESULTS

WORKER HAS LITTLE CHANCE OF AFFECTING THE OUTCOME

LESS LIKELY TO GENERATE

EMPLOYEE OBJECTIONSADVANTAGES

Work SamplingIT DOES NOT DIVIDE WORK ELEMENTS (THERBLIGS) AS THOROUGHLY AS FORMAL TIME STUDIES

IT CAN YIELD INCORRECT / BIASED RESULTS IF THE OBSERVER DOES NOT CONFORM TO RANDOM ROUTES OF TRAVEL AND RANDOM OBSERVATION

IT TENDS TO BE LESS ACCURATE WHEN CYCLE TIMES ARE SHORT

DISADVANTAGES

Work Measurement & StandardsApplied Management Science for Decision Making, 1e 2011 Pearson Prentice-Hall, Inc. Philip A. Vaccaro , PhD