Work Sampling. A technique that discovers the proportions of total time that various activities contribute to the job by taking a relatively large
2. Work Sampling
4. Probability based on the binomial distribution (p + q)n = 1
Mean = np, Variance = npq
As n becomes large, the binomial distribution approaches the normal distribution
This proportion has distribution of Mean = p, Variance = pq/n
5. 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)/(L2) Theory
6. A work sampling study requires 95-percent confidence with five-percent accuracy. How many observations are required if the machine down time is eight percent?
n = (1.960)2*(1-0.08)*0.08/(0.05)2
n = 225,76 observations
Example of Sample Size Calculation
7. Sample Size Table
8. Randomized Time of Observation
22. Questions & Comments