An important technique for analysing the effect of categorical factors on a response is to perform an Analysis of Variance.
An ANOVA decomposes the variability in the response variable amongst the different factors.
Depending upon the type of analysis, it may be important to determine:
(a) which factors have a significant effect on the response, and/or
(b) how much of the variability in the response variable is attributable to each factor.
1. One-Way ANOVA - used when there is only a single categorical factor. This is equivalent to comparing multiple groups of data.
2. Multifactor ANOVA - used when there is more than one categorical factor, arranged in a crossed pattern. When factors are crossed, the levels of one factor appear at more than one level of the other factors.
February 15, 2018