For the Technical Trader
US Dollar Index
How Does the United States economical data effects the market?
If you are trading the US Dollar against another currency it is also a good idea to do your technical analysis on the US index as well, but mostly on the daily scale to give you an idea of what might probably happen to the price action and in which direction you should trade.
If the US Dollar index goes up only currency pairs where the USD is the base currency will move in the same direction, where the US Dollar is the quote currency like in GBPUSD or EURUSD will move in the opposite direction.