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Re: [Phys-L] Indicators of quality teaching



I found this explanation helpful.Perhaps you will indulge me a little further:
Is the standard deviation calculated from the pre test, or from the post test results?
Is the maximum possible score selected for the pre test, or for the post test?

Brian Whatcott

On 6/22/2013 12:03 AM, John Clement wrote:
STD is standard deviation, which is calculated from the aggregate of scores.
Max score would be the maximum score attainable. So if you use the raw
score and there are 23 questions the max would be 23. But if the test is converted to a percentage then the max score would be 100.

John M. Clement
Houston, TX

On 6/21/2013 7:19 PM, John Clement wrote [in part]:


Effect size = (post - pre)/STD
An effect size of 1 is considered enormous and many studies
do not get effect sizes larger than .5. Many PER practicioners get effect sizes greater than 1.

But this definition of gain has the problem that it is skewed by the size of the pre-test and also is highly dependent on class
homogeneity. Just a straight post-pre has a large dependence on the pre test. So Hake came up with Hake gain or normalized gain.

Normalized Gain = (post-pre)/(max score - pre)