Leaving the community

In article ,
Jose wrote:

and there is the problem - can you really estimate or bound the error
from all the error sources (e.g., people not participating or
deliberately lying to the poll)?

Yes.

You cannot "bound" the error in an absolute sense, except to say that it's no
bigger than the total population, which is useless. However, if a poll is
done right, you can estimate the likely error. For example, "95% of the
time, the error will be
less than 1%. 98% of the time, the error will be less than 5%" (I'm making
these numbers up since they depend on how well the poll is conducted, and how
big the sample size is, etc). This is where the standard deviation of the
mean comes in as an
estimate of how good your measurement is.

This is true only if you know the distribution function.

--
Bob Noel

This [putting a bound on the likely error] is true
only if you know the distribution function.

One of course never =knows= the distribution function. However, one can make reasonable estimates ("guesses", if you will) based on ones sampling methods and experience with previous polls (comparing past polls with elections for example). True,
your guess of the distribution function might be off, but if you do things right, it's probably close. How close? Well, there's a distribution function to describe that too.

One doesn't even know the sun will come up the next day, but as a working theory it seems to be more than satisfactory. Statistics is not mumbo jumbo, although it is true that real mumbo jumbo can be disguised as statistics.

Jose
--
Freedom. It seemed like a good idea at the time.
for Email, make the obvious change in the address.
(note to r.a.student: I only follow r.a.piloting and r.a.ifr, to which this is also posted)