[danteembermage]

I think a key point is that, unless planets rotate in a plane that nearly osculates our line of sight vector they will not be observed by current methods. Basically any planet whose orbit from our perspective looks like an oval rather than a left-right wobble will not be observed by current methods which check for light flickers as the planets cross their star. There are complex factors at work here, but I'd think a reasonable approximation would be that solar systems plane of rotation are oriented randomly.

So, given random rotation, if we would expect to observe 1 out of 100 plants using this method and then find that there are planets around 1 out of 200, we can extrapolate that (1/100)/(1/200)= 1/2 of suns have planets. That explains the discrepancy anyway; since so many don't rotate in the right plane the fact that we observe them at the frequency we do, rare as it is, means they are in fact quite common. The universe just got a lot more exciting!