Time Study Method Step 1...Selecting Work Elements Step 2...Timing the Elements Step 3...Determining Sample Size Step 4... Setting the Standard

Step 1 Step 2 Selecting Work Elements Timing the Elements Definite starting and stopping points Correspond to a standard work method Analyst times a worker –Continuous method –Snap-back method “ Irregular occurance “ Select time (t)

Step 3... Determining Sample Size 1/2 Average time estimate close to true long range average n = [(z/p)(σ/t)]² –n = required sample size –p = precision of the estimate as a proportion of the true value –t = select time for a work element (w.e.) –σ = standard deviation of representative observed times for a w.e. –z = number of normal standard deviation needed for the desired confidence Fallbeispiel: Workelement Standard deviation Select Time Sample Size Get two cartons Put liner in carton Place cups in cart Seal carton

Step 3... Determining Sample Size 2/2 Sample size of each Work Element Work Element 1 n = [(1.96/0.04) (0.0305/0.500)]²= 9 Work Element 2 n = [(1.96/0.04) (0.0171/0.11)]²= 58 Work Element 3 n = [(1.96/0.04) (0.0226/0.71)]²= 3 Work Element 4 n = [(1.96/0.04) (0.0241/1.10)]²= 2

Step 4... Setting the Standard 1/3 Normal time for each work element NT = t(F)(RF) –Perfomance rating factor (RF) –Frequency of occurance (F) Normal time for the cycle (NTC) NTC = ΣNT Fallbeispiel: Workelement t F RF Get two cartons Put liner in carton Place cups in cart Seal carton

Step 4... Setting the Standard 2/3 Normal Times of each Work Element Work Element 1 NT 1 = 0.53(0.50)(1.05) = 0.28 minute Work Element 2 NT 2 = 0.10(1.00)(0.95) = 0.10 minute Work Element 3 NT 3 = 0.75(1.00)(1.10) = 0.83 minute Work Element 4 NT 4 = 1.08(1.00)(0.90) = 0.97 minute Total = 2.18 minutes

Step 4... Setting the Standard 3/3 Allowance Time:ST = NTC(1 + A) Standard time for the coffee cup packaging operation Solution for A = 0.15 ST = 2.18( ) = 2.51 minutes/carton Production standard for eight-hour day (480 minutes/day) / (2.51 minutes/day) = 191 cartons/day Overall Assessment of Time Study –Not useful for tasks that are different each time –Inexperienced persons should not conduct time studies –Subjectivity is involved –BUT: Conducted by experienced observers  satisfactory tool for setting equitable time standards

3 Methods Elemental Standard Data Approach Predetermined Data Approach Work Sampling

Elemental Standard Data Approach -- Highlights -- Decreases the number of time studies Time studies are saved as elemental standard data in a database Define other job standards Job standards before production begins

Elemental Standard Data Approach -- Attention! -- Does not eliminate time studies! Check new job standards from time to time (gap between theory an reality). Not the best method

Predetermined Data Approach No time studies. Micromotions instead of work elements Time unit for a micromotion is Time Measurement Unit (TMU) 1 TMU = minute = 36ms Get TMUs from public databases (i.e. Methods Time Measurement (MTM)-databases like MTM- 1). Basic micromotions in MTM-1 are reach, move, position, turn, release,…

Predetermined Data Approach -- Steps to the job standard -- 1.Divide each work element into micromotions 2.Find a database for the micromotions’ values (TMUs, factors,…) 3.Sum up the normal times for each micromotion (= normal time) 4.Calculate the standard time with the normal time and the allowances (factors, constant values).

Predetermined Data Approach -- Example -- A worker has to move an 18 pound object to an exact location 20 inches away.

Predetermined Data Approach -- Table 1 – MTM predetermined Data for the Move Micromotion -- Distance Moved (in.)ABCHand in Motion B 3/4 or less2221,7 12,52,93,42,3 23,64,65,22,9 34,95,76,73,6 46,16,984,3 57,389,25 68,18,910,35,7 78,99,711,16,5 89,710,611,87,2 910,511,512,77,9 1011,312,213,58,6 1212,913,415, ,414,616,911, ,818,712,8 1817,61720,414,2 2019,218,222,115,6 2220,819,423, ,420,625,518, ,827,319,8 2825,523,12921,2 3027,124,330,722,7 Additional0,80,60,85TMUs per inch 30+ CaseDescription AMove object to other hand or against stop BMove object to approximate or indefinite location. CMove object to exact location Weight Allowance Wt. (lb.) Up toDynamic FactorStatic Constant (TMU) 2,510 7,51,062,2 12,51,113,9 17,51,175,6 22,51,227,4 27,51,289,1 32,51,3310,8 37,51,3912,5 42,51,4414,3 47,51, * ,9= 28 TMUs

Predetermined Data Approach ++ Job standards before production begins Compare work methods without time studies Consistency in setting time standards (i.e. no recording errors from time studies) Biased judgment is eliminated No time studies

Predetermined Data Approach -- Dividing work element into micromotions Impractical for products and services with low repeatability Micromotions may not fit exactly to the work Not all data are in the databases (i.e. the shape of an object). The sum of the micromotions may not fit to the time really needed for the job (gap between theory and reality) Misuse of the method

Work Sampling Method -- Goals/Possibilities -- Time which is needed for a specific activity by a worker or machine. Effectiveness of machines or workers Job content Cost of jobs or activities Allowance time for the 2 Methods above (i.e. resting time, fatigue,..)

Work Sampling Method -- Procedure -- 1.Activities (what is going to be measured?) 2.Observation form 3.Length of the study 4.Sample size 5.Observation times 6.Observer schedule 7.Observe the activities and record the data 8.Additional sampling is required?

Work Sampling Method -- defining activities -- Activities could be … Producing a product or service Doing paperwork Waiting for instructions Being idle

Work Sampling Method -- sample size -- Estimate the proportion of time spent on a specific activity, which doesn’t differ from the true proportion by more than an error e. p Sample proportion (number of positive divided by sample size) e …… maximum error in the estimate

Work Sampling Method Binomial distribution of the sampling and a big sample size Approximation to a normal distribution to determine the sample size.

Work Sampling Method -- sample size -- The sample size affects the degree of precision n …… sample size z …… number of standard deviations needed to achieve the desired confidence

Work Sampling Method -- Example -- Medical records storage and retrieval system Determine Advisability of Purchase Registered Nurses – RNs Licensed Vocational Nurses – LVNs Ward staffed by 8 RNs and 4 LVNs Proportion of time spent accessing records

Work Sampling Method -- Example -- Time spent accessing records takes estimated about 20 % of RNs and 5 % of LVNs time Requirement: 95 % Confidence that the estimate falls within of true proportion Sample size ???

Work Sampling Method -- Example -- RN: LVN:

Work Sampling Method -- Example -- 8 RNs and 4 LVNs can be observed on each trip RNs: trips LVNs: trips  688 observations of RNs 344 observations of LVNs

Work Sampling Method -- Example -- Results of the Initial Study

Work Sampling Method -- Example -- Annual amortization costs for the new system $ (estimated) System reduces time nurses spend accessing records by 25 % (estimated) Total anual salary expense RNs $ LVNs $ Nurses could use productively time saved by system

Work Sampling Method -- Example -- Additional Sampling required ?? RNs 124  LVNs 28  Original estimates off the mark  sample size smaller FaultTolerance  between 0.15 and 0.21

Work Sampling Method -- Example --

Net Savings: 0.25[( $)(0.18) + ( $)(0.08)] $ = $ Worst Case 0.15 (RNs) & 0.05 (LVNs) Net Savings 0.25[( $)(0.15) + ( $)(0.05)] $ = $

Work Sampling Method -- Overall Assesment -- Advantages:  No special training required  No stopwatches needed  Simultaneous Studies  activities of groups, rather than individuals Major Disadvantage  Large number of brief observations