On 4 Feb 2001 06:53:19 -0800, [EMAIL PROTECTED] (Paul W.
Jeffries) wrote:
> I have been thinking about levels of measurement too much lately. I have
> a question that must have a simple response, but I don't see it right now.
> The textbooks say that a ratio scale has the properties of an interval
> scale plus a true zero point. This implies that any scale that has a true
> zero point should have the cardinal property of an interval scale; namely,
> equal intervals represent equal amounts of the property being measured.
>
> But isn't it possible to have a scale that has a true zero point but on
> which equal intervals do not always represent the same magnitude of the
> property? Income measured in dollars has a true zero point; zero dollars
< snip, rest >
I agree, you have been thinking about it "too much."
I think you have to take Stevens's hierarchy of scaling more lightly.
It is a handy starting point. But it does lead to paradoxes (such as
what you point to) and misconceptions. For instance, you seem to
accept that the "scale" is inherent in the system of measurement,
rather than in the use to which it is put. From your question, you
seem to be ready to consider the "application" and that is what's
fundamental.
Dollars, inches, seconds, degrees Kelvin -- all these may be used as
"ratio" measures. However, if you are looking at "healthy body
temperature", temperature is not even ordinal.
Additional dollars will buy the same additional number of peanuts, but
if your concern is the psychology of wealth, the "interval metric"
certainly isn't dollars.
Hope this helps.
--
Rich Ulrich, [EMAIL PROTECTED]
http://www.pitt.edu/~wpilib/index.html
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