Joseph Coveney <[email protected]> asks:
> Is there a reason why -test- after -anova , sequential- uses partial sums of
> squares?
There isn't a really good reason, but for background as to why it
acts the way it does, consider how the -sequential- option (and
the default option -partial-) of -anova- work. These options are
allowed on replay. You can type
. anova y a b a*b
which by default displays the Partial SS results. You can replay
the anova and have it switch to showing Sequential SS results
with
. anova , sequential
The default is always -partial-. So, even if you say
. anova y a b a*b, sequential
when you then replay that with
. anova
you will be shown the partial SS results. To replay the anova
showing sequential SS you have to say
. anova , sequential
Stata's -anova- stores the same information regardless of which
of the -sequential- and -partial- options are specified. What is
displayed is different -- derived from the underlying information
based on which of the options is specified.
By the time that -test- comes along after -anova-, it does not
know if -anova- was specified with the -sequential- option or
not. -anova- does not save that information since the
-sequential- and -partial- options are considered replay options.
There probably should be an option for -test- to use sequential
SS, just as there is for -anova-, but there currently is not.
Ken Higbee [email protected]
StataCorp 1-800-STATAPC
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