Referendums

1) The whole idea of the democratic process is that the will of the nation (in this case, Catalonia) is determined through democratic means - that is, the will of the nation is inferred from those that choose to make their voices heard.

2) Merely voting in an election or referendum doesn't immediately imply you support or defy one position, party, etc. - voting "No" in the referendum doesn't mean you supported a "Yes" position any more than answering the question "Are you right-handed or left" with "Right-handed" mean you're left-handed, merely because you answered the question.

3) Even if you try to dispute it using the relatively low voter turnout to lessen the disparity required between the electorate and the voting public to delegitimise it, the enormous majority means you'd still need a severely unlike amount of the currently non-voting electorate, and there still has to be far more of a margin of error than would be expectable or likely, even from non-official polls. Assuming a disparity of 30% between the electorate and the voting public would render any almost any current democratic government illegitimate.

4) The statistics derived from referendum results aren't biased. What is biased, is your decision to dispute a referendum, the most official and reliable way possible of gauging public opinion, in a way that requires such a drastic and groundless departure the results collected. There's no more reason to assume the required number of non-voters in order to uphold a "No" position supported a "No" position, than there is to assume that an even greater number of non-voters supported a "Yes-Yes" position than voters.

5) I'm dropping this, I can't be arsed with it now, it's going in circles. Before I leave, I'm leaving you with this, I think you could use it: http://i.imgur.com/daTcExL.jpg