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# Re: st: Pooling Data

 From Dennis Kramer <[email protected]> To [email protected] Subject Re: st: Pooling Data Date Thu, 14 Apr 2011 21:06:50 -0400

```given that the X and Y are both achievement on the same subject-- math
--  (just calculated differently) could I not apply a pooled
regression coefficient function after estimating the OLS regression
models for each district?

On Thu, Apr 14, 2011 at 7:52 PM, Nick Cox <[email protected]> wrote:
> I agree with Joerg. The question sems to be: I have measures for
> variable y in area A and x in area B, and how can I compare them? I
> can't see that you do anything without a cross-calibration between y
> and x.
>
> Nick
>
> On Fri, Apr 15, 2011 at 12:48 AM, Joerg Luedicke
> <[email protected]> wrote:
>> On Thu, Apr 14, 2011 at 7:23 PM, Clive Nicholas
>> <[email protected]> wrote:
>>> Dennis Kramer replied:
>>>
>>>> I am  attempting to compare the effectiveness of teachers in two
>>>> districts (based on a common evaluation tool) where the student test
>>>> scores outcomes are calculated differently. the first district
>>>> calculates the scores on a cumulative gain index standardized across a
>>>> number of factors and the other district uses a value-added index.
>>>
>>> I think I'll do my best impersonation of a David Greenberg posting and
>>> say that, to me, your problem appears to cry out for a multilevel
>>> modelling solution, perhaps via -gllamm-.
>>>
>>
>> I do not know how a multilevel model would be of help here, besides
>> there only being 2 districts, which is not enough anyway. But first
>> and foremost, this seems to be a measurement problem. I do not know
>> anything about these two indices but if they are picking up different
>> stuff and one index cannot be translated into the other, I guess then
>> the data from the two districts cannot be combined.
>
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```