Re: regression to the mean

[Paul R Swank]

divide at the midpoint of the pretest to form two equal size groups.

At 01:37 PM 1/17/01 -0500, you wrote:
>At 12:28 PM 1/17/01 -0600, Paul R Swank wrote:
>>But if you group the subjects on the basis of their pretest scores, the
>>lowest group gains 23.1 points while the highest group only gains 19.2.
>>Looking at the graph, I note that the person who scored 34 on the pretest
>>did not increase as much as I might expect while the person who scored 10
>>increased more than I might expect. The best fit line is obviously flatter
>>than the best fit l;ione for the pre and post tests.
>
>
>not sure what you are referring to as the low and high ... but the data
>below has been sorted on the pretest from high to low ... and, then i
>looked at the mean gain for the low 6 (on the pre) and the top 6 (on the
>pre) and found ..
>
>
>> >if i sort the pre from high to low and then list the gain ... we can see
>> >easily that the high pres gain more in fact, the top 6 gain about 51 points
>> >on average ... while the low 6 gain only about 35 points on average
>
>thus, unless you did some quite different calculations ... i don't see
>where you get a gain of 23 for the low and 19 for the top?
>
>whenever one discussed RTM ... they seem to talk about the upper level
>group (near the top) and the lower level group (near the bottom) and that
>is exactly what i did
>
>
>
>
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------------------------------------
Paul R. Swank, PhD.
Professor & Advanced Quantitative Methodologist
UT-Houston School of Nursing
Center for Nursing Research
Phone (713)500-2031
Fax (713) 500-2033

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