```Date: Tue, 9 Jan 2007 09:54:21 -1000 Reply-To: Bob Schacht Sender: "SPSSX(r) Discussion" From: Bob Schacht Subject: Re: Treating Ordinal Data as Continuous Comments: To: "Swank, Paul R" Content-type: text/plain; charset=us-ascii; format=flowed At 07:00 AM 1/9/2007, Swank, Paul R wrote: >The problem is compounded when one thinks of measurement scales as all >or none, it's either ordinal or interval. However, win, place, and show >in a horse race is clearly more ordinal that IQ scores. For IQ scores, >it is clear that the difference between an IQ of 50 and an IQ of 75 is >perhaps greater than th difference between 75 and 100. On the other and, >the difference between an IQ of 100 and 101 is probably pretty similar >to the difference between 99 and 100. It all relies on the relation >between the scale values and the underlying construct. I think some >scales are closer to being interval than ordianl while for others, the >opposite is true. A lot has to do with how well the scale was >constructed. My main concern with this issue comes from satisfaction and importance scales. It seems to me that we don't have enough tools regarding ordinal measures. The analytical tool set for interval data is far richer than what is available for ordinal data. The median can be substituted for the mean, but there is no analytical equivalent of variance, even though it makes intuitive sense that an ordinal scale with results congregating at the extremes ought to be more 'variable' than a scale in which the results congregate around the median. Bob Schacht Robert M. Schacht, Ph.D. Pacific Basin Rehabilitation Research & Training Center 1268 Young Street, Suite #204 Research Center, University of Hawaii Honolulu, HI 96814 ```

Back to: Top of message | Previous page | Main SPSSX-L page