Question about use of 1-Sample Sign test

Hi,

I have collected some data and am trying to find a method of attaching
a statistical significance to a hypothesis about the data. This is the
first time I have collected data for analysis and I think my data
(questionnaire) design
may have been flawed so I am now trying to salvage what I can from the
final data.

The data:
Consists of 50 responses indicating preference for the design of a
website. Possible responses include:

Prefer Website A (+1)
Have No Preference (0)
Prefer Website B (-1)


What I'm trying to do:

I "think" that by attaching numerical values (in brackets above) to
each response I can perform a 1-Sample Sign test. What I want to do
with this test is to test the hypothesis that the median of the data is
>0 (i.e. more people preferred Website A). I am doing this by testing a
null hypothesis that the median is equal to 0 with an alternate
hypothesis that the median is greater than 0. If that p value generated
from this test is less than 0.05 I accept the alternate hypothesis,
otherwise I must accept the null hypothesis.

What I would like to know:

I have got this far by reading various text books but I am still
unclear about certain aspects, these are:

Can I viably perform this test (i.e. is it ok to associate numbers with
each response? I think it is as it results in non-parametric data which
is what the 1-Sign sample test is designed for)

Why is the accept / reject level for the null hypothesis set at 0.05?
This is something I have come across in every example in books and on
the internet but it has never been explained. Is it something to do
with a 95% confidence interval?

If this is not a suitable test to perform, does anyone have any
suggestions of tests which might be suitable?

Lastly, if this is a suitable test to be performing, does anyone have
any references towards good books or websites that I can use to further
understand the test mechanism?

Many thanks in advance of anyone's reply.

Cheers,

Edd

Disclaimer. Last time I posted I was pretty much flamed for attempting
to perform statistics without having the required knowledge!! I am
doing this out of necessity as it for my degree dissertation. I
acknowledge there may be many
things I am not doing correctly but I am a Software Engineer and not a
statistician, this is why I have posted this request for info. So
please go easy on me!

http://www.mredd.co.uk

.

Relevant Pages

  • Re: Ballpark this one for me
    ... lead to a potentially wide range of true and false responses. ... there is a 95% chance the TRUE value lies within those +/- limits. ... After all, some exact number of the population, in theory, lies on ... statistics aren't meaningful in a way practitioners would have you believe ...
    (rec.gambling.poker)
  • Re: Question about use of 1-Sample Sign test
    ... Possible responses include: ... > Prefer Website A ... > This is something I have come across in every example in books and on ... > Lastly, if this is a suitable test to be performing, does anyone have ...
    (sci.stat.edu)
  • Re: Advice requested regarding method of data analysis
    ... > Participants will, to some 'significant degree', find Website A to ... > looking at the frequency of each response. ... moderately well (say at the Ph.D. level of statistics) as it takes ... RF> cutting up skulls in brain surgery after reading a paper back ...
    (sci.stat.edu)
  • Re: Safespeed lies and the Press Complaints Commission
    ... Igave you credit for watching the thread, not just responses to yur own ... interpretation of some of the headline statistics might have been ...
    (uk.rec.cycling)