-----Original Message-----
From: David Brauer [mailto:[EMAIL PROTECTED]]
Sent: Friday, September 06, 2002 11:22 AM
To: Anderson, Sue
Subject: Re: MPS Webpage Information
Sue - can you send this to the issues list? [EMAIL PROTECTED]
Thanks for looking it over!
Best,
David
on 9/6/02 10:32 AM, Anderson, Sue at [EMAIL PROTECTED] wrote:
> David,
> Although no "statistical expert" (and it's been many years since my
college
> classes), the questions I would have after reviewing the website data are
> these:
>
> + No coefficients of variation are shown in the relatively simplified
> graphs. As these are significantly affected by the number of observations
> (students) in each category, it would be expected that for some groups
these
> might be quite large (small number of students) vs. the larger groups.
This
> could result in "overlapping data" which would indicate no real
statistical
> differences across groups or "years of reduced class size". The large
sample
> size (3022 students) as a whole would probably show the trends, since this
> is a statistically valid sample size, but individual sub-categories (years
> or "race") might not show a significant trend.
>
> + There is no category of "Caucasian" or "Other", so technically a claim
> cannot be made that "All races" benefit, as not "All races" are
represented.
>
>
> + A point made previously in other contexts is that these studies are
> conducted using various methodologies: some seem to track the "same
> students" through the timeframe (in this case 9 years apparently,
> 1990-1999); others seem to track "classes" or "schools" which may be more
> dynamic. There is no indication as to the method used in this study, and
no
> indication of how "random" the sampling was. I would "guess" that there
> would be wide variations in MBST test results between samplings at
different
> schools in the District (ref. recent Star Trib articles and other info
> published by the District). So without more information it's difficult to
> judge if there really is sufficient "randomness" to draw conclusions
across
> the whole MPS spectrum.
>
> + No indication is given as to the age categories this data was taken
from,
> nor is there any analysis of "self-selection factors" which may be
occuring
> over the 9-year timeframe. The starting student number is the same as the
> ending student number apparently. The study indicates it is a
"longitudinal
> study", but there is no additional data. Over the 9 years, if the "same
> group" was tracked, students dropping out at differential rates across
> "races" would tend to impact the data. If it's statistically "random"
across
> schools and district, demographic variations within the MPS students would
> impact the data.
>
> If this research has been published in a more complete form (preferably in
a
> refereed journal), many of these questions may be answered. As it stands,
> the website makes "claims" that wouldn't seem to be substantiated by what
we
> see.
>
>
> Sue Anderson, live in Phillips , work in Fridley
>
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