On Mon, 24 Apr 2000, Timothy Graves wrote:
> I could really use a little advice.
> I am preparing a research paper proposal for my M. Ed. I am not
> sure on a few issues:
> Is ANOVA is a suitable form of t-test to determine if there is any
> significant differences between the means of three different subject
> groups on a Likert scale instrument?
> Am I off base here? Any suggestions?
'Twould be nearer the mark to say that the t-test is the special case of
ANOVA when there are only two groups. Is ANOVA suitable for your
situation? Probably. Some would dispute that, if by "a Likert scale
instrument" you mean a single bipolar scale with Likert-like responses.
If you mean an instrument comprising a bunch of items, each item being
Likert scaled, and you are summing (or, equivalently, averaging) a
subject's responses to all those items, hardly anyone would argue against
using ANOVA. The usual alternatives are less desirable for a variety of
reasons, som eof which have recently been posted on the edstat list.
> I am also trying to decide upon what internal-consistency method is
> suitable to use in determining the Reliability of a Likert scale
> instrument? Kuder-Richardson approaches? Alpha Coefficient?
Well, as some of my colleagues will cheerfully point out at the drop of a
hat, "reliability" is not a characteristic of an instrument. However you
choose to measure it, it reflects the behavior of a particular group of
persons who have responded to the instrument, and thus depends on (inter
alia) the homogeneity of the responding population(s), the homogeneity of
the items in the instrument, etc. Do you have a compelling reason to
obtain a reliability coefficient at all, or to settle on any particular
one in your proposal? (I suppose a compelling reason is that one or more
of your committee members demands such a thing; but I meant substantive
or logical reasons.) What do you think you'd do with such a thing, once
you'd got it?
My general advice regarding proposals is not to promise more than
you're sure you can deliver, not to commit yourself to any details that
you can avoid, and not to belabor the obvious. If your proposal entails
some comparison among several groups, ANOVA or an ANOVA-like procedure is
obviously going to be required; you need not say so (unless you need
more boiler plate than I would accept in a proposal!) in writing, and in
oral questioning you need only indicate, rather off-handedly, that of
course ANOVA is one obvious way to address such comparisons. But it is
entirely imaginable that you will have other variables lurking around,
perhaps even explicitly measured, and that some more general linear model
than ANOVA would be useful to apply -- a variant of multiple linear
regression, for example, of which ANOVA is a particular family of
subsets.
Is that Likert scale instrument something of your own devising,
or is it an extant device of some sort? If it's original with you, your
committee may well feel that some sort of instrument development phase
might be desirable, or even necessary; though I wouldn't usually expect
that at the M.Ed. level. If they do require you to do some of that,
you'll need to know something about measurement in general, and should
read up in some of the elementary texts in the area. (And if they do
require anything of the sort, ask them whether the instrument-development
phase would suffice for your magistral research. I've known that to be
accepted in a Ph.D. proposal at OISE, when the area of proposed research
really had no instruments to speak of, and the candidate was going to be
spending a lot of time, energy, and theory on developing an instrument to
measure what she needed to measure if she were ever going to carry out
the research she had in mind in the first place.
> This is my first crack at this type of research, and any help in this
> regard would be greatly appreciated.
Hope this has helped some.
-- DFB.
------------------------------------------------------------------------
Donald F. Burrill [EMAIL PROTECTED]
348 Hyde Hall, Plymouth State College, [EMAIL PROTECTED]
MSC #29, Plymouth, NH 03264 603-535-2597
184 Nashua Road, Bedford, NH 03110 603-471-7128
(Professor Emeritus, Department of MECA, OISE)
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