Dennis Roberts wrote:
> the term 'null' does NOT mean 0 (zero) ... though it is misconstrued that
way
> the term 'null' means a hypothesis that is the straw dog case ... for
which
> we are hoping that sample data will allow us to NULLIFY ...
> in some cases, the null happens to be 0 ... but in many cases, it does not
It always means that _something_ is zero - as does just about any other
algebraic or mathematical expression, after a little rearrangement into
something logically equivalent . Moreover, in cases in which the null
hypothesis has any prior credibility - as should always be the case - that
"something" (eg, amount by which the IQ of the subject population differs
from the standardized value of 100) is usually a sensible thing to study.
And that thing can usually be thought of as "effect size".
In the classic student blooper cases: "H0: mu = x bar" and "H0: mu
equals the nearest round number to x bar" it isn't: and those tests should
not be done.
-Robert
===========================================================================
This list is open to everyone. Occasionally, less thoughtful
people send inappropriate messages. Please DO NOT COMPLAIN TO
THE POSTMASTER about these messages because the postmaster has no
way of controlling them, and excessive complaints will result in
termination of the list.
For information about this list, including information about the
problem of inappropriate messages and information about how to
unsubscribe, please see the web page at
http://jse.stat.ncsu.edu/
===========================================================================
