To do each example, just click the "Submit" button. You do not have to type in any R instructions or specify a dataset. That's already done for you.
Note: In the friedman.test function call the
"groups" variable goes in front of the vertical bar and the "blocks"
variable goes behind the vertical bar. We are looking for a "method"
effect here so method goes in front of the bar.
The second analysis done by the aov function is the
usual parametric procedure: two-way ANOVA. It produces
P = 0.004084 for comparison with the Friedman P-value.
The first line tells R that player is to be treated as
a factor
, that is, as a non-numerical variable. If it were
omitted, the ANOVA would be nonsense. For some
reason friedman.test comes out the same if it is omitted.
We don't also have to tell R that method is a factor,
because it automatically treats any non-numerical variable as a factor.
If method had been designated by numerical codes, we would also need
a statement like the first line for method.
If R were consistent, these two analyses would have similar syntax, but it isn't and they don't.
Warning: Do not omit the lines converting the categorical
variables to R factor objects. At least don't omit them unless
you are sure it won't make a difference.