Introduction To Work Sampling  >  Work Sampling Principles

Work Sampling Principles

Randomized observations -

Randomness is the golden key to work sampling. It operates on every level for the study to be valid and accurate. What randomness means when it is applied to time is that during the study each minute is just as likely as any other minute of being picked.

  1. Determining the observation time points using the Random Numbers. Before ISampler this was a pain because of the difficulty of manually performing the calculations or manually remembering to do observations at the times recommended by the random tables. ISampler transformed the randomization process into a simpler task that can be performed automatically, without any manual user intervention.


  2. Choosing the subjects that will be evaluated in the study. If the target population is large, the decision to analyze only a portion of the population, chosen randomly, in such a way that is considered to be a reflection of the target population. Results obtained by studying this representative sample will then be extrapolated to the entire population.
Instantaneous and unbiased observations -
it is important to capture the activity that the individual is performing at the moment of observation and not what he has just finished or is about to do next. Going even further, the task evaluation must be registered immediately after the random signal has been received.
Work Sampling Limitations
The limitations of work sampling methodology consist of the following:
  • Work sampling is based on a quantitative measurement. It does not offer qualitative insights, like the quality of work or individuals strengths and weaknesses.
  • Using observers or operating by self-reported logs leave room for inter-individual differences in the way of categorizing activities and selecting the correct category.
  • Although unlikely, the "Hawthorne effect" might appear. This effect is defined by a change in the individual behavior of the subject, subsequent to the observer appearance or beginning of self-reported logs.
Work Sampling and Other Work Measurement Methodologies

Often work sampling is compared with time-motion methodology. Time-motion is performed by a trained observer, who continuously follows and monitors multiple trials of selected activity, registering time for every part of the activity.

The main difference between the two methods resides in the degree of intrusion perceived by the subject. Work sampling is less invasive being defined by momentary observations, compared to the continuous observation done in time-motion studies.

Work sampling can offer cross-sectional analysis performed over an extended period of time (weeks or even months), while time-motion would imply higher cost levels by studying large time frames. By including a diverse sample of subjects, work sampling results can be segregated by team, department, shift, down days vs. operating days, week days vs. week-end days or by any other information specific to the organizational structure.

Through numerous researches, statisticians have shown that the results obtained through work sampling methodology are statistically similar to the corresponding 100% behavioral observation data.

The usage of sampling technique can now be extended even further to larger groups of individuals. Until now, this type of studies was thought to be too expensive even if sampling inferences were used. Also, the possibility to transfer the data collection task from consultants to the subjects of the evaluation, eliminate the costs of external consultancy.

ISampler demolishes the technical barriers that existed so far, researchers are faced now with the ideal environment for improving the methodology and extending its scope and coverage.

Because of their cost and time attributes,work sampling and other related methodologies, like time study, have been used mainly on evaluating physical tasks. More recent research looks at the possibility to encompass also the application of these methodologies in measuring behavioral, cognitive and affective aspects of work. Assessing the qualitative aspects of processes, such as team work, communication skills, problem solving, professional behavior, design or ethics, often require the examination of behavior from multiple cognitive and affective levels.

The application of work sampling in assessing cognitive and affective aspects allows researchers to evaluate more broadly individual's contribution to the group's outcome.