Notice: This is a discussion thread for comments about the SitePoint article, Build Your Own Data-backed Personas.
One major issue with Personas, they are not real and are often based on non existent people. Try explaining to a client that you have just spend x hours building personas that are pretend people that don't exist based on no real user research data. That my friends is a hard sell.
If you base the personas on more than the statistical data at hand and user research methods such as interviews or focus groups are used, then I have found that you often end up with more or sometimes less personas than you expected as they are based on real people. Yes this costs a little more but its easier to sell to marketing and the bean counters.
That's not to say the quick and dirty (read agile) personas generation method isn't good. It's just it will only be a guideline at best.