> It would be great if longitudinal studies of huge populations existed, but... That's the problem, isn't it. There's so many things we would know if only we

> It would be great if longitudinal studies of huge populations existed, but... That's the problem, isn't it. There's so many things we would know if only we had better data. However, until we actually have useful data, we have to simply acknowledge that there is insufficient data to say anything worth saying. To do otherwise is unscientific.