ARTICLE SYNOPSIS ...The Common (But Useful) RSI by Herbert S. Hall, C.M.T. The relative strength index (RSI) is one of today's most popular indicators and is available in virtually every technical analysis software package sold. While the RSI indicator has become so common that some would-be users feel it has lost its effectiveness, calculating changes in RSI values clearly would give the user an advantage over those who calculate it with corresponding price levels only after the close. To do so, take a detailed look at how the RSI is calculated, how to determine appropriate values for it and, finally, how to us...