It looks as if many of the quality energy stocks have now dip down to attractive buy ranges according to their relative strength. I am normally early in my initial entry prices, but since I advocate dollar cost averaging, building a position is less stressful than buying an entire position with one trade. Here is the definition of the Relative Strength Index or RSI:

"The RSI compares the magnitude of a stock's recent gains to the magnitude of its recent losses and turns that information into a number that ranges from 0 to 100. It takes a single parameter, the number of time periods to use in the calculation- Source StockCharts.com

Many investors use the Relative Strength readings on a stock to judge where to buy and sell a stock. As a basic rule of thumb, when a stock reaches a RS level of 40 or below, investors buy. When a stocks RS reaches 70-80, investors like to sell.