To ensure that your results are valid, consider the following guidelines when you collect data, perform the analysis, and interpret your results.
- Operators should measure parts in a random order
- To ensure that the data collection order does not influence the results, each operator should measure all parts randomly within a replicate. After all operators measure all parts one time, you repeat the process for all replicates.
- Operator and Part factors must be crossed
- Two factors are crossed when each level of one factor occurs in combination with each level of the other factor.For example, if the Operator and Part factors are crossed, every operator must evaluate every part. For more information on crossed factors, go to What are crossed and nested factors?.