In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (Paul W. Jeffries) writes:
> ...
> 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.
No, you've reversed the direction of the implication.
> 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
> is the absence of income. Yet, an increase in income from say 18,000 to
> 19,000 is not the same as an increase in 1,000,000 to 1,001,000. At the
> low end of the income scale an increase of a thousand dollars is a greater
> increase in income than a thousand dollar increase at the high end of the
> scale.
See the discussion of log-interval scales in
ftp://ftp.sas.com/pub/neural/measurement.html
--
Warren S. Sarle SAS Institute Inc. The opinions expressed here
[EMAIL PROTECTED] SAS Campus Drive are mine and not necessarily
(919) 677-8000 Cary, NC 27513, USA those of SAS Institute.
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