How to meassure corrency strength?

[coverman]

If I want to make an EA which is checking the strength of different currencies, how can I meassure them. Since they are connected in pairs I'm not sure.
Should I compare the overbought/oversold in different pairs to see which one is stronger?
Any ideas?

My idea is to see if eg the USD is stronger compared to other pairs. And if EUR is weaker. Then that pair would be a nice trade.
Is this possible to make with the standard indicators when making an EA? I know there are a lot of indicators showing correlation in lines and that way it's easier to see what currency is on it's way down and which one is on it's way up. But it would be nice to make this in an EA.

Just checking if someone out here have any ideas what to start with.