The Sharpe Ratio measures the relationship between a fund's returns and its volatility or risk, with a higher ratio indicating relatively less risk. It is calculated as the average return minus the risk-free rate divided by the standard deviation of returns. The Sortino Ratio is similar but uses downside deviation instead of standard deviation to exclude upside volatility and better measure only harmful volatility. Both ratios can help investors assess risk and select less volatile funds when the Sharpe Ratio may be lower due only to upward, not downward, price movements. For example, the Sharpe Ratio of Tata Infrastructure Fund was 0.0899 and the Sortino Ratio was 12.796 for the three-year period from June 2006 to May 2009.