Market Pricing Relative to Yesterday's Market Prices Market Irrationality Can Outlast You

Market Timing Using Economic Indicators

The tricky part about trying to determine the state of the economy is that most indicators are either lagging or coincidental rather than leading. When an indicator is "lagging" it means that the indicator changes only after the fact. That is, a lagging indicator can confirm that an economy is in recession, but it doesn't help much in predicting what will happen in the future.
Source: http://www.investopedia.com/articles/02/100402.asp