You can use fractional analysis (a partial factorial) to determine which variables are important. Fractional analysis can designate variables to be used in designed experiments. It can also be used to generate clues when other methods have not worked.
This appendix explains fractional use in more detail than Chapter 7. It explains and describes the required calculations. These calculations are not difficult, and any investigator will become proficient after creating one or two fractional.
If you don’t recall the problem presented in Chapter 7, review the piston-stuffing data sheet and the resulting piston-stuffing interaction ...