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