A recent study suggests that as we are busy looking for them, they are looking back at us. The current method we use is seeking extraterrestrial life (and we’re talking microbes here or anything that would qualify as life, even barely) by finding a planet that we feel meets the needs for life (don’t get me started on that!) then seeing if there is an atmosphere. If there is, what’s it made of? Now we are considering they may be an intelligent and more developed lifeform. SO - if the atmosphere has complicated things such as chloroflurocarbons, then likely someone’s there making it!
Basically they’re looking for stuff that doesn’t occur ‘in the wild’ but it could be simpler components in unlikely measurements – such as oxygen & methane.
Anyway – forget all that and think like an alien. You are an alien and you are looking for us much like we are looking for you. You have your own Kepler project and spend your time obsessing over exoplanets and their transits in front of their host stars – except maybe those planets are in the Milky Way, in this Solar System, perhaps one of them is a planet called Earth! So, what more do you do? Do the same thing that is being suggested here.
The thought is that this alien civilization that is looking for us, may have also sent us a message. So in addition to the above considerations, when we find an exo-planet that meets the necessary requirements, we listen really hard. If a message were maybe sent a real long time ago, and we know what direction to listen in, we may stand a chance of locating the signal and hearing it.
So, have we narrowed it down significantly? Made the search for intelligent life easier and now hold a road map to where they are? Yes and No. Yes, it has significantly cut down where we have to look, but NO because that list includes 10,000 star systems with planets that need to be checked out. Actually suppose this method actually chooses a target zone which has a real life alien civilization that has attempted contact. What if we listen for one day, two days, maybe three and miss it and move on. How long is long enough.
Still, this theory has some good ideas – but the Universe is a big place and Aliens may be playing hard to get!