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Chapter 16: One-Way Analysis of Variance
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Definition: Treatment or Level of a Factor
An experimental condition which is applied to the experimental units is
called a treatment or level of the factor.
Note:
Sometimes the word treatment is used interchangeably with the term level or
maybe combined as “treatment level”.
Factors may be qualitative.
Definition: Qualitative Factor
A qualitative factor is a factor that has levels that may vary by category
rather than by numerical values.
Factors can also be quantitative.
Definition: Quantitative Factor
A quantitative factor is a factor that has levels that may be counts or
numerical measurements.
In the example where we used different teaching methods, we refer to these
different methods as the treatments or levels of the factor of teaching. In the
example where the researcher wanted to determine whether there were
differences in mileages for the different brands of gasoline, the different
brands of gasoline will be the treatments or levels of the experiment. In the
case where the researcher wanted to determine the effectiveness of different
drugs on lower back pain, then the different drugs will be the treatments or
levels of that experiment. Thus, one can infer that ANOVA is designed to
detect differences among means for different populations subject to different
treatments or levels based on sample data.