Hmm, it's quite possible you know more about statistics than me, but...

Usually equations for calculating confidence level are based on the 
assumption of a random sample, not a volunteering self-selected sample.

If you have a self-selected sample, then the equations for "how likely 
is this to be a fluke" are only accurate if your self-selected sample is 
representative; and there aren't really any equations that can tell you 
how likely your self-selected sample is to be representative, it depends 
on the circumstances (which is why for the statistical equations to be 
completely valid, you need a random sample).

Is my understanding.

On 12/5/2012 2:18 PM, Rosalyn Metz wrote:
> Ross,
>
> I totally get what you're saying, I thought of all of that too, but
> according to everything I was reading through, the likelihood that the
> survey's results are a fluke is extremely low.  Its actually the reason I
> put information in the write up about the sample size (378), population
> size (2,250), response rate (16.8%), confidence level (95%), and confidence
> interval (+/- 4.6%).
>
> Rosalyn
>
>
> On Wed, Dec 5, 2012 at 1:52 PM, Ross Singer <[log in to unmask]> wrote:
>
>> Thanks, Rosalyn for setting this up and compiling the results!
>>
>> While it doesn't change my default position, "yes we need more diversity
>> among Code4lib presenters!", I'm not sure, statistically speaking, that you
>> can draw the conclusions you have based on the sample size, especially
>> given the survey's topic (note, I am not saying that women aren't
>> underrepresented in the Code4lib program).
>>
>> If 83% of the mailing didn't respond, we simply know nothing about their
>> demographics.  They could be 95% male, they could be 99% female, we have no
>> idea.  I think it is safe to say that the breakdown of the 16% is probably
>> biased towards females simply given the subject matter and the dialogue
>> that surrounded it.  We simply cannot project that the mailing list is
>> 57/42 from this, I don't think.
>>
>> What is interesting, however, is that the number roughly corresponds to
>> the number of seats in the conference.  I think it would be interesting to
>> see how this compares to the gender breakdown at the conference.
>>
>> This doesn't diminish how awesome it is that you put this together,
>> though.  Thanks, again to you and Karen!
>> -Ross.
>> On Dec 5, 2012, at 1:28 PM, Rosalyn Metz <[log in to unmask]> wrote:
>>
>>> Hi Friends,
>>>
>>> I put together the data and a summary for the gender survey.  Now that
>>> conference and hotel registration has subsided, it's a perfect time for
>> you
>>> to kick back and read through.
>>>
>>> [Code4Lib] Gender Survey
>>> Data<
>> https://docs.google.com/spreadsheet/ccc?key=0AqfFxMd8RTVhdFVQSWlPaFJ2UTh1Nmo0akNhZlVDTlE
>>>
>>> Gender Survey Data is the raw data for the survey.  Not very interesting,
>>> but you can use it to view my Pivot Tables and charts.
>>>
>>> [Code4Lib] Gender Survey
>>> Summary<
>> https://docs.google.com/document/d/1Hbofh63-5F9MWEk8y8C83heOkNodttASWF5juqGLQ1E/edit
>>>
>>> Gender Survey Summary is easy to read version of the above -- its the
>>> summary I wrote about the results.  Included is a brief intro, charts
>> (from
>>> above), and a summary of the results.
>>>
>>> Let the discussion begin,
>>> Rosalyn
>>>
>>> P.S. Much thanks to Karen Coyle for reviewing the summary for me before I
>>> sent it out.  Also if there are any typos or grammar mistakes, please
>> blame
>>> my friend Abigail who behaved as my editor.
>>
>
>