Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.stat.math.independent

Topic: Help with a school project, a statistical survey on education
Replies: 15   Last Post: Jul 13, 2013 4:14 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
loom91

Posts: 17
Registered: 4/25/06
Re: Help with a school project, a statistical survey on education
Posted: Jul 23, 2007 9:04 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

On Jul 23, 8:36 am, Richard Ulrich <Rich.Ulr...@comcast.net> wrote:
> On Sun, 22 Jul 2007 18:36:50 -0000, loom91 <loo...@gmail.com> wrote:
>
> [snip, some previous and replies. Just to reply to one
> point]
>
>
>

> > We plan on taking 50 data points from each school, about 20-25% of the
> > class size. So you say that we should take the same number of points
> > even if one school has more students than the other? Also, do you mean
> > that the sample size is insufficient to draw reliable conclusions
> > about whether coed schools really lessen the gender differences?

>
> The earlier poster tried to make this point, and I will
> try again. Whether you are comparing 50 or 500
> students from two schools, you are only comparing
> *two* schools. Or six schools. Within the schools,
> there is a lesser hierarchy, perhaps, of a dozen
> teachers -- or whatever. If you see differences between
> two schools, is it something idiosyncratic to those
> two schools, or idiosyncratic to that selection of a
> dozen teachers?
>
> If you want draw an inference about "schools", it is
> almost necessary to have a large number of *schools*
> represented. There is a statistical approach that tries to
> test across multiple strata, but that quickly gets complicated.
>
> With two schools, or a few schools, you can easily
> do comparisons, by t-tests or ANOVA, that tell you whether
> these particular schools seem to "differ". That can be a
> starting point for discussing all the *wrong* reasons that
> might exist that could account for the differences.
> Selective admissions? Selective attrition? Particular
> teachers?
>
> Even when there are 50 or 500 *schools* being sampled,
> the resulting "inference" (whether coed schools differ) can
> be challenged for systematic biases. With a large number
> of schools, it begins to be possible to argue that various
> factors have been measured, and that they indeed do seem
> to be balanced or equivalent between schools, or otherwise
> accounted for.
>
> With a few schools -- try to keep the questions simple, and
> try to keep the conclusions well-tempered by doubts.
>
> I'm sorry I can't be of more help to the questions that you
> pose.
>
> --
> Rich Ulrich, wpi...@pitt.eduhttp://www.pitt.edu/~wpilib/index.html


Thanks, I think I get your point. When comparing types of schools, the
data points are actually the schools themselves and in that case there
are only 5 (possibly 8) data points. Well, we have to work within our
abilities. It is clearly beyond our abilities to collect and analyse
data from hundreds of schools. We will work with what we have and see
what we can arrive at.

Molu




Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.