Proceeding. International Seminar on Industrial Engineering and ManagementMenara Peninsula, Jakarta, August 29-30, 2007 ISSN: 1978-774X

WORK SAMPLING COMPARATIVE AMONG CONVENTIONAL, SELFASSESSMENT, AND CONTINUOUS MONITORING METHODS TO

MEASURE PROPORTION OF NON PRODUCTIVE ACTIVITIES

Roy Agustinus I, Hotniar Siringoring021,2lndustrial Engineering and Management, Faculty ofIndustrial Technology, Gunadarma University

JI. Margonda Raya No. 100 Depok 164242hotniars@staff.gunadarma.ac.id

ABSTRACT

This research was done to compare three methods, i.e., conventional, self assessment, and continuousmonitoring methods in measuring non productive activities in Bureau of Administration and StudentAffairs (Biro Administrasi Akademik dan Kemahasiswaan - BAAK), Gunadarma University. Preresearch was conducted to measure non productive activities using conventional method Selfassessment was conducted using questionnaire as research instrument, handy cam was used to observework activities in the same period of time as the two methods mention before. Hypothesis tested towardnon productive activities. among the three methods using paired t- test. The result shows thatconventional and continuous 'methods measured non productive activities significantly different. Theresult also shows that continuous method measured non productive activities significantly different withthe one measure by conventional and self assessment methods.Key words: work activities, conventional method, continuous method

INTRODUCTION

Services performing by Bureau ofAdministration and Student Affairs (BiroAdministrasi Akademik dan Kemahasiswaan -BAAK) Guna-darma University for campuslocated in D, E, G, and H are centered in D area,building 4, floor 1. Services perform either on-line nor off line. Services off line employ humanresources, which is interact face to face withstudent as customer.

One of the consequences of interaction isqueuing. Queuing is unwanted condition byevery customer. Queuing can be reduced byanalyzing existing work system and designingbetter work system if needed.

The objective of this research is tocompare non-productive activities ratio measuredby three methods, i.e. conventional method, selfreport, and continuing controlling.

THEORETICAL BACKGROUNDS

Work Sampling

L.H.C Tippett is the first time of using worksampling method. The method was used toobserve textiles industry worker. In 1940, worksampling also known as delay ration of activities.Work sampling is a tool used to find facts. Inmost cases, work sampling can reduce cost and

Work Sampling Comparative Among.....Hidayat

time spending for production (Barnes, 1980).Niebel (2003) defined work sampling astechnique used to measure productive activitiesproportion..

It's advantage compares to conventionalmethod (Barnes, 1980), is suitable to use whendealing with lot of activities with non practicalmeasurement. Using work sampling is possibleto observe more than one operator or machine atthe same time with one observer. On continuoustime studying, usually one observer needed forone operator/machine.

Work sampling also more efficientcompare to continuous time studying based onwork time and cost. Cost can be reduced until 5-50% of continuous time studying cost.Observation is possible be conducted in dayrange or week, but it'll give impact on datavariance. Work sampling doesn't need a timestudy expert in conducting sampling, exceptperformance sampling needed. When standardtime or performance index expected, a time studyexpert is needed. Even though there ispossibility disturbance on work samplingmethod, the result will not be effectedsignificantly.

Work sampling measurement can beconducted in varies interval confidence. Usingwork sampling, quick observation towardoperator can be done in random interval.

Bl

Proceeding, International Seminar on Industrial Engineering and ManagementMenara Peninsula, Jakarta, August 29-30, 2007

Employing quick observation can reduceunimportant observation.

There three advantages of work samplingaccording to Wignjosoebroto (1992). Firstadvantage is to measure delay ratio of activity.Second advantage is to measure performancelevel based on working or delay status,particularly for manual work method. Lastmethod advantage is to identify standard time ofan operation.

Worker with high level commitmentcontinuously conduct work sampling to measuretheir performance (Niebel, 2003). For most ofself report case, it's found that worker spendsmaller portion of their time to do importantthings, as they think do. As reverse, they spendmore time on unimportant things, such as delay

.' or postponing something unimportant beyondtheir prediction.

Work sampling also can be done usingvaries tools or supporting equipment, such asmoving camera recorded with 1000 picture perminute accuracy. Another tool is electronicequipment with code used to translate directly tocomputer daily, weekly, or monthly. Another isportable picture recorded known as handy cam.

Video camera is usefulness to produceun bias work sampling (Niebel, 2003). Onobservation spot, data collected tend to be bias ifsampling study done toward individual or groupperformance. The existence of an observer ispossible in raising disturbance toward operatoractivity on work condition. There is tendency towork motivated when an observer as observer

comes to close. Bias can be produced by anobserver when he/she write what have beenhappened or will happen.

RESEARCH MEmOD

This research need some tools, i.e. videocamcorder SONY video hi8 ccd-trv418e (l unit),and stopwatch. This research also used materialssuch as video hiS cassette, pen, and observationform. Video and cassette used to record allactivities when continuous observation method

applied. Pen and observation form used whenself assessment and conventional methods wereapplied. Stopwatch was used when conventionalmethod was applied.

Data used taken from three sources,according to method applied. Conventional worksampling employ random number table as a

B2

ISSN: 1978-774X

measurement of time. Based on randomize leveland quantity of observation (n) predefined,observer make sign on observation form insuitable cell.

Research variable are productive andnon productive activities. Productive activitiesdivided into 5 categories, i.e. keying, pointing,reading, writing, and handling document. Non-productive activities differentiate into twocategories, i.e. allowance (rest, personalactivities, praying, eating, drinking, etc.), andunemployed.

Data Collection Technique

Data collected using observation method.Sample quantity to be collected on first day iscalculated based on quantity of pre observationdivided with total of observation days (N-l).Sample quantity on second day equal to total ofsample on pre observation and first day dividedby N-l. Interval confidence used is 95%, orsignificance level of 5%.

Self report filled 5 days continuously,with 4 hours range productive time. Workerasked do fill out given form 30 times a day. Thetime schedule to write the activities was decidedby worker. Random table is not used to decidewhen the activities should be written.

Continuous activities recorded using ahandy cam at 09.30-15.00 o'clock, during 5 dayswork days (excludes Saturday and Sunday).Recording is playing as long as 90 min. timerange 90 min is chosen in order to simplifycalculation. For 5 days observation, 450 mineach day, will be resulted 9005 observation.Sample to be observed was chosen randomly.

In second measurement, the observationwill be in 27.000 seconds duration. Using 3seconds range, the observation was written to aform provided. T overcome bulky data,productive and non productive activities is drawnusing tally diagram.

Data Analysis

Hypotheses test is used to compare the threemethods.

Work Sampling Comparative Among.....Hidayat

Proceeding, International Seminar on Industrial Engineering and ManagementMenara Peninsula, Jakarta, August 29-30, 2007

RESULT AND DISCUSSION

Conventional Work Sampling

Pre work sampling was done as much as 61times, with 4 minutes interval. Observation wasstarted at 09.00-11.30, continued at 13.02-14.58.

The summation of allowance andunemployed activities result non productiveactivities proportion as much as 0.2131. With qvalue from pre studied, sample quantity (N)needed for next observation using confidenceinterval 95% (or significance level 5%) is 258samples.

ISSN: 1978-774X

Observation time was decided 5 days.On Saturday, student services is open from 09.00- 12.00 o'clock, shorter than other days. Asresult, division factor for first day only 4.5 days.And so observation frequencies for first day are44 samples (N).

Using random table, 95 random numberswere resulted. Every number is used mutuallyexclusive. Based on mutually exclusiveproperty, from 95 numbers were resulted 33numbers. The II numbers remain were searchedusing other random numbers. The activitiesperformed on day one is shown on Table I.

Table 2. Frequencies of n~n-Day

Nonproductiveactivities

Non productive activity on day one (p)is 0.2727 and productive activity (q) is 0.7273.With p value from predetermined research,proportion total of activities non productive on

day one (p) ) is 0.2381.Sample size needed for 95% confidence

of interval is change, becomes 279 andobservation total for day two (N2) is 50 sample.Proportion of non productive activity on day twowas calculated as much as 0.26, and soproductive activity is 0.74. Given p and pi,proportion mean of non productive activity on

day two (P2) is 0.2451. Proportion total of

productive activity on day (q 2 ) then becomes0.7549. Samples size (N) needed for 95% of

Work Sampling Comparative Among.....Hidayat

interval confidence is 285 unit and 52observation sample on day three (N3).

Using random table as before, afterdeleting duplication random number and outsiderange, observation time was resulted 52 times onday three.

Proportion of non productive on daythree (P3)is 0.2884. This fact resulted productiveactivities proportion on day three (q3) is 0.7116.Given p, Ph and P2, Proportion total of non

productive activities on day three (P3) is

0.2560. And so, proportion total of productive

activities on day three (q3 ) is 0.7440.

B3

Non productiveDay

Handling document Allowance Unemployed

Is

0 I 11I

3 6 6 22 5 8

1 I 6 I 2 2 5 17 4 8

2 7 2 3 4 21 4 9

3 8 7 3 2 17 4 II

4 9 8 6 3 19 5 8

5 1 5I

1 4 0 5 4 4

Total I 46 I 23 24 20 101 26 . 48

99 I 21 I 29

Proceeding, International Seminar on Industrial Engineering and ManagementMenara Peninsula, Jakarta, August 29-30, 2007 ISSN: 1978-774X

Based on data until day three, samplesize (N) needed for 95% confidence of interval(or 5% of level significance is 293 samples.

Frequencies of observation for day four(N4) is 58 sample. As done before, random tableused and started from 508 sequences until 856.Having eliminates chosen random number beforeand outside range, and so found 58 observationson day four.

Based on 58 observations on day four,non productive activity (P4) is 0.2241 andproductive activity (q4) is 0.7759. Given p, pI, P2and P3,mean of non productive activity until day

four is (P4) 0.24905. Mean of productive

activity until day four (q4 ) becomes 0.75095.

Including sample on day four, total ofsample becomes 288 units. Observationfrequency on day five is 23 units. Observation onlast day (on Saturday), divisor is not used. Thisis due to time schedule services. Services onlyopen during 150 minutes.

As consequences, all number bigger than37 can't be included on observation. Havingapplied elimination and outside range, it's foundthat observation time for last day is 23 times.

Non productive activity proportion onday five (Ps) is 0.3478. Productive activity (qs)on the other side is 0.6522. Given p, pI, P2, P3,and P4,mean of non productive activity until day

five (Ps) becomes 0.25694 and so mean of

productive activity (qs ) becomes 0.74306.

Work Sampling Using Self Report

Form provided for self report returned 13exemplars. There is 275 data used as input tocalculate non productive activity. Proportion of

A

non productive activity (P2) is 0.18182 andproportion of productive during five days is0.81818.

Based on calculation, accuracy level ofquestionnaires is 4.5585%. And so, significancelevel of 5% is fulfill.

Work SamplingObservation

Using Continuous

Having recording operator activities during fivedays, saved in 6 video cassette 90 min, VCD

produced. Activities are summarized using tallydiagram. Activities recorded, first, transferred toVCD format. In order to write observation, VCDplayer playing slower four times than normalvelocity.

It's found 1060 samples categorized asnon productive activities on 60 time intervalobservation, whereas observation frequencies are30 to 31, during 90 minutes. By summingallowance and unemployed of non productiveactivity until day five, it's found proportion of

A

non productive activity until day five (P3) is0.49939.

For interval confidence 95%, it showsthat accuracy level (I) of continuous observationduring five days is 1.03 %, and so significancelevel of 5% is fulfill.

The result is supported by samplequantity, i.e. sample minimum required with95% confidence of interval for non productiveactivity are 385 samples.

Based on non productive activityobservation above, non productive activityproportion using conventional method is0.25694, self report is 0.18182, and continuousobservation is 0.49939.

Testing of hypothesis in comparing nonproductive activity measured by each method isconducted using t-test. Hypothesis to be testedare:

1. There is no difference of non productiveactivity produced between conventionalmethod and self report.

2. There is difference of non productiveactivity produced between conventionalmethod and self report.

Test result shows that there is significantdifference on non productive activitymeasured using conventional method andself report. Significance employed is 0.05.Based on non productive calculation above,it is logic to say that self report over inidentify productive activity (0.25694conventional method compare to 0.18182self report)..

Comparing non productive activitymeasured by self report and continuousobservation was conducted using t-test, with:

1. There is no difference of non productiveactivity measured between self reportand continuous observation.

B4Work Sampling Comparative Among.....

Hidayat

Proceeding, International Seminar on Industrial Engineering and ManagementMenara Peninsula, Jakarta, August 29-30, 2007

2. There is difference of non productiveactivity measured between self reportand continuous observation.Significance test employed is 0.05.

Hypothesis test showed the rejection oh nullhypothesis, means there is difference of nonproductive activity measured between self reportand continuous observation. Non productiveactivity measured using continuous observationis 0.50061. It means that self report method overjudge to report their activities.

It's still need to compare non productiveactivity measured using conventional andcontinuous observation methods. Hypothesistesting is:

1. There is no difference of non productiveactivity measured between conventionaland continuous observation methods.

2. There is difference of non productiveactivity measured between conventionaland continuous observation methods.Result showed the rejection of null

hypothesis and acceptance of alternativehypothesis. And so we can say there issignificance different on non productive activitymeasured using conventional and continuousobservation methods.

Non productive activity measured usingthe three methods is different each other. Selfreport method result in smaller of non productiveactivity proportion, followed by conventionalmethods. There is possibility un-honesty inusing self report method, because worker askedto report their daily activity. The result showedby continuous observation method is close toreality, because worker was observed using nonstop handy cam. The reliability of data providedusing continuous observation then is higher thanthe two methods.

CONCLUSION

There are significant differences on nonproductive activity measured using conventional,self report, and continuous observation methods.Based on non productive activity calculation, selfreport method measured smaller non productiveactivity than two others methods. Continuous

Work Sampling Comparative Among.....Hidayat

ISSN,' 1978-774X

observation method measured non productiveactivity smallest among the three methods.

Non productive activity proportion ofself report is 0.18182, conventional method asmuch as 0.25694, and continuous observationmethod is 0.49939.

REFERENCES

Barnes, Ralph Mosser. 1980. Motion and TimeStudy Design and Measurement ofWork, 7th edition, John Willey & SonsInc.

Homan, Michelle M. and Armstrong, Thomas J.2003. Evaluation of ThreeMethodologies for Assessing WorkActivity During Computer Use,American Industrial HygieneAssociation Journal 64.

Niebel, Benjamin W. and Frevalds, Andris, 2003.Methods, Standards and Work Design,11th edition, McGraw-Hill Inc.

Sutalaksana, I.Z., dkk. 1979. Teknik Tata CaraKerja, Teknik Industri ITB, Bandung.

Walpole, Ronald E. dan Myers, Raymond H.1995. Ilmu Peluang dan Statistikauntuk Insinyur dan Ilmuwan, ITB,Bandung.

Wignjosoebroto, Sritomo. 1992. Teknik TataCara dan Pengukuran Kerja, ITS,Surabaya.

B5