Post on 28-Mar-2015
Work Sampling
INSY 3021
Auburn UniversitySpring 2007
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
Work Sampling
Well suited for high cycle time and low repetition rate jobs & service industry
Does not require the analyst to continually observe the job
Reduced clerical time A smaller # of hours are required to
collect the data Operator not subjected to long
periods of observations
Advantages
Single analyst can study a small crew (or # of subjects); GTT (Maynard Handbook)
Cost of the study may be cheaper (up to a certain # of samples)
Conducted over a long period of time (tends to be more objective)
Study can be postponed if something more urgent arises (no change in study criteria)
Advantages (con’t)
Will not produce as good a standard as direct time study
Cost maybe higher than suspected if sampling rates are frequent
Subjects need to be located close together to eliminate travel
Doesn’t provide the detailed data (C/I ideas) that direct study does
Theory of why it works is confusing for some people
Disadvantages
Based on an event being present or not. Probability of x occurrences of an event in n
observations: (p + q)n = 1 Expand IAW binomial theorem, with the 1st term
giving the probability of x=0, the 2nd term x=1, etc…
This distribution of probabilities is known as the binomial distribution, with the Mean = np, and Variance = npq.
As n becomes large, the binomial distribution approaches the normal distribution
We’ll return to this later…
Little bit of 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)(A2)
Sample Size
n = 162308
Z = 2.326P = 0.25A = 0.01
Confidence Z99.9% 3.25099% 2.32695% 1.96090% 1.645
Start with preliminary estimate of the variable. This can be historical data, conducting pilot study, or an educated guess (least desirable)
Determine the desired accuracy of the results
What level of confidence do you desire Estimate the # of observations Develop a sampling schedule Design the data collection form
Study Plans (Protocol)
Random number tables (text pg. 697)
Random number generators C++ Program Websites
Random Reminder
Determining Randomness
Forms should be custom designed to accommodate the specific data of interest to your study. Make the spaces large enough to easily record the data. Provide summary and calculations spaces right on the form.
Commercial software available for this application
Work Sampling Form (Instrument)
Locate yourself at the same place each time prior to observing the operation
Try to intentionally distract yourself from the variable of observation as you approach the site (think safety)
Limit your time at the site to that actually needed for the observation
Technique
Try to record only the minimum data that you will need to successfully reconstruct the observation
Verify any discrepancy with the supervisor or foreman
Make notes on the form after the operator can no longer see you
Keep a pleasant attitude
Technique (con’t)
Computer and PDA programs Quetech Ltd, TimerPalm, UMT-Palm
Advantages IE time increased by a reduction in clerical time,
results realized faster More professional appearing report $ of performing studies is cheaper Improved accuracy Reduced errors by analysts Greater use made of work sampling, because it is
less painful
Computerized Work Sampling
Title Determining staffing requirements in institutional pharmacy
Objective To determine if improvements can be made to workload & staffing patterns of a satellite pharmacy; determine the percentage of an employee’s day which was devoted to specific activities
Sample 1 pharmacy
Type of sampling
Predetermined times
Length of study 3 weeks (day, evening, & night shifts)
Data Collection Direct observation
# Observations 2400 (300 per shift)
Work Sampling Studies
Title Task analysis of a pharmacist’s activities in a 45-bed rural hospital with comprehensive pharmaceutical services
Objective Determine how a pharmacist’s time was used; calculate the portion of the work day spent in clinical pharmacy activities; compare allocation of time in this service with that of pharmacists in a small hospital with product-oriented systems; investigate potential usefulness of supportive personnel
Sample 1 pharmacy
Type of sampling Fixed intervals – 5 minute intervals
Length of study 18 days selected randomly work days (stratified to insure equal representation of each day) over a 6-month period
Data collection Direct observation - 5 trained observers
# Observations 1,451
Work Sampling Studies
Title What Are the Functions of a Practicing Pharmacist?
Objective Detailed examination of what pharmacy operators do with their time
Sample 20 pharmacies (stratified into 4 levels based on prescription volume); 93 pharmacists
Type of sampling
Fixed intervals – 3 minute intervals; stratified based on prescription volume
Data collection Direct observation – 1 observer
Length of study 36 hours (stratified to insure each day of week and hour of day were adequately represented)
# Observations 14,400
Work Sampling Studies
Title Work activities of pharmacy teams with drug distribution and clinical responsibilities
Objective Evaluate pharmacists’ and technicians’ use of time for patient care.
Sample 7 pharmacy teams (3-9 pharmacists & 1-4 technicians per team)
Type of sampling
Random time interval (8 observations / hr / shift)
Data collection Self reporting
Length of study 5 months
# Observations 11,485 pharmacist observations; 7,626 technician observations
Work Sampling Studies
Title Work Sampling: As a Win/Win Management Tool
Objective Detailed examination of what pharmacy operators do with their time –seeking ways to improve the efficiency of the operation.
Sample
Type of Sampling
Random intervals (20-25 observations/shift)
Data Collection Self reporting
Length of study 3 months
# Observations 2518 samples
Work Sampling Studies
Title Work Sampling: The Application of an Industrial Research Technique to School Library Media Centers
Objective Apply work sampling in a school library media center setting
Sample 1 media center; 2 media specialists
Type of sampling
Random time interval (4 observations per hour)
Data collection Self reporting
Length of study 20 days
# Observations 400
Work Sampling Studies
Title Work Sampling: Assessing nursing efficiency
Objective Determine how nurses utilize their time
Sample 16 RN’s; 10-12 CNA’s; 3-4 secretaries
Type of sampling
Predetermined times (20 minutes each shift)
Data collection Direct observation
Length of study 24 hours (4 day shifts, 4 evening shifts, 2 night shifts on weekdays and weekends)
# Observations 2,835
Work Sampling Studies
“Sell” the work sampling method before using it
Use as large of a sample size as is practical
Take individual observations at random times, balance the study if necessary
Take the observations over two weeks or more
Summary
Questions & Comments