WORK SAMPLING AND STRUCTURED ESTIMATING. CHAPTER 12. Work sampling is a method of finding the percentage occurrence of a certain activity by statistical sampling and random observations.
Work sampling is a method of finding the percentage occurrence of a certain activity by statistical sampling and random observations.
The major goal of work sampling is to determine how long, or how much of the work day, is spent on specific types of work.
1. Establish the Purpose
2. Identify the Subjects
4. Establish a Time Period
5. Define the Activities
7. Schedule the Observations
9. Record the Raw Data
10. Summarize the Data
Establishing confidence levels
To make things easier, it is more convenient to speak of a 95 per cent confidence level than of a 95.45 per cent confidence level.
Statistical method. The formula used in this method is:
Let us assume that some 100 observations were carried out as a preliminary study and at random, and that these showed the machine to be idle in 25 per cent of the cases (p = 25) and to be working 75 per cent of the time (q = 75).
Nomogram methodAn easier way to determine sample size is to read off the number of observations needed directly from a nomogram such as the one reproduced in figure 91.
Looking at these numbers, we find that we have to discard 87, 68 and 49 because they are too high (since we have only 48 ten-minute periods, any number above 48 has to be discarded).