The sample is allways unbiased unless proven otherwise.
I'm sorry, you've got that backwards. A sample is only useful if the margin for error is known. The margin for error can only be known if all possible measures to eliminate selection bias have taken. Ideally that means a fully blind selection of the full population.
Since this survey is taking place on a fansite forum, you've inherently created a sub-set of the population that has different characteristics than the target population. We have no data on the characteristic differences of the population of this forum from the population at large, so our margin for error is undefined. Data=garbage.
You didn't understood my argument. As you said the survey can be rightfully used to describe Dfans population. theres no selection bias. Thats the first argument.
The second argument is that one can use the estimated value in this site (the diference between wizard users in the old and present surveys) and assume this value represent a shift that 've occured in the population. Unless theres some reason to believe dfans and the general population behaves differently you can say any changes here represents a change outsides of here.
Theres no prove both behaves equally but theres no prove they behave differently.
Actually the size of the population is not terribly important when determine margin for error and sample size. 1000 people should get you around or under a 3% margin of error for a poll like this.
The real problem, is that the participants in the survey are not representative of the population in question, so none of the data turned out by the poll is useful for any question beyond determining opinions of D3fans.com forum users.
Finnaly someone who knows at least the basics of statistics and inference.
An 200~300 sample is more then enough to survey D3 population. I bet people who said otherwise didn't runned the tests or don't know how to do it. Also about the sample bias: unless you give a theorycal reason why dfans behaves unlike the population and why this difference makes then hate wizard more you can't argue the sample 've bias.
The sample is allways unbiased unless proven otherwise. Basically because statistcally any sample IS unbiased unless something strange happens. It might be that some "anti wizard" movement is taking place in this site and not on the whole population. Still you have to explain and prove your point before denying the statistical evidence.
Rollback Post to RevisionRollBack
"In time the hissing of her sanity
Faded out her voice and soiled her name
And like marked pages in a diary
Everything seemed clean that is unstained
The incoherent talk of ordinary days
Why would we really need to live?
Decide what is clear and what's within a haze
What you should take and what to give" - Opeth
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You didn't understood my argument. As you said the survey can be rightfully used to describe Dfans population. theres no selection bias. Thats the first argument.
The second argument is that one can use the estimated value in this site (the diference between wizard users in the old and present surveys) and assume this value represent a shift that 've occured in the population. Unless theres some reason to believe dfans and the general population behaves differently you can say any changes here represents a change outsides of here.
Theres no prove both behaves equally but theres no prove they behave differently.
Finnaly someone who knows at least the basics of statistics and inference.
An 200~300 sample is more then enough to survey D3 population. I bet people who said otherwise didn't runned the tests or don't know how to do it. Also about the sample bias: unless you give a theorycal reason why dfans behaves unlike the population and why this difference makes then hate wizard more you can't argue the sample 've bias.
The sample is allways unbiased unless proven otherwise. Basically because statistcally any sample IS unbiased unless something strange happens. It might be that some "anti wizard" movement is taking place in this site and not on the whole population. Still you have to explain and prove your point before denying the statistical evidence.