http://spssx-discussion.165.s1.nabble.com/ANOVA-with-patents-as-DV-tp5720812p5720821.html
You do need to improve your understanding of the terminology.
Your IV, investment stage, is a set of categories that certainly do
appear to be "ordinal" even though you may not want to use that
fact in your analysis. From Seed to Later certainly does seem like
a definite ordering in time.
The usual classification includes "categorical" (or "nominal") which
is unordered; "ordinal" which is ordered by not interval, where the
rank-transformation allows tests that potentially are more efficient
than ignoring the inherent order; "(equal) interval" which allows
ANOVA; and "ratio" which has a natural zero, and mainly suggests
the potential for natural power transformations of a scale that is
ordinal into one that has "equal intervals" in respect to the dimension
that is being modeled. ("Ratio" is a term that is seldom used usefully,
and what I've suggested here is not what you will usually see.)
Your DV of "number of patents" is apparently a count, so it has more
potential uses than "discrete" = "nominal" = "unordered categories."
What ANOVA requires for valid testing is a criterion IV that is reasonably
close to "equal interval" so that the size of errors-in-prediction are not
different for low versus middle versus high scores. In practice, this is
judged by whether the "equal intervals" on the scale, from 0, 1, ... , 99,
100, ... are considered (a) equally predictable, and (b) of equal importance.
Is the difference between 0 and 1 of similar "magnitude" as the difference
between 99 and 100? A dichotomy is automatically "equal interval"
since there is only one interval, so, Yes, it can be an IV in ANOVA.
Contrary to your statement, an Ordinal variable is not automatically
valid in ANOVA, as IV or as DV. It is labeled "ordinal" instead of "interval"
*because* there is doubt about whether the intervals are equal. Being
ordinal, it has potential to be transformed to ranks or by square root or log
or what-have-you to become a variable that can be analyzed by ANOVA.
- For samples that are not too tiny, the classical rank-order tests are
essentially equivalent to ANOVA conducted on a rank-transformed version
of the scores.
Hope this helps.
--
Rich Ulrich
> Date: Wed, 19 Jun 2013 13:08:03 +0200
> From:
[hidden email]> Subject: ANOVA with patents as DV
> To:
[hidden email]>
> Dear all,
>
> This might be a stupid question but I'm quite new to this. I want to run a ANOVA with one categorical independent variable (investment stage; 4 levels: Seed, Early, Expansion and Later) and my DV is number of patents. However, the way I understood using an ANOVA your DV should be either continuous, ordinal or dichotomous. My DV is # of patents, this is discrete, right? Can you still do a anova with a discrete DV like this?
>
> Thank you very much in advance.
> ...