[idlehand]

For example, a group such as Hispanic voters can be slowly growing over decades as a result of higher fertility.

But their voting patterns may change from one election cycle to another. Hispanic voters are not so solidly Democrat as they have been. So if in 2006 you forecast that the growth of the Hispanic community would tip the scales in favor of Democrats by 2016, you'd be in for a surprise.

I used to think that the future of the US was Democrat rule due to demographics, now I'm not so sure. I think other factors will weigh heavier.

You can do a forecast assuming everything stays static, and note the point where fertility will be the deciding factor. But because fertility is such a slow process compared to most of politics, your forecast would be quite inaccurate.

I suppose the best summary I can make is that political party messaging and voter group preferences will evolve a lot faster than group sizes due to differences in fertility. Trends in turnout are more relevant in your typical political timescale. By the time fertility has had an impact, your forecast is far enough into the future that you have a lot of unknown unknowns, and so it doesn't tell you that much.

I'm sorry if that doesn't make it clearer, it's quite late on a Friday for me but I decided to leave all explanations I could think of so you can pick which ones make sense. I might be wrong too, of course. I have no relevant qualifications in the subject.

[bhouston]

Thanks this is informative. I understand what you are saying.