"The Standard & Poor's Index Versus Active (SPIVA) methodology is designed to provide an accurate and objective apples-to-apples comparison of funds’ performance versus their appropriate style indices, correcting for factors that have skewed results in previous index-versus-active analyses in the industry. SPIVA scorecards show both asset-weighted and equal-weighted averages, include survivorship bias correction to account for funds that may have merged or been liquidated during the period under study, and show style consistency for each style group across different time horizons." (quoted from the SPIVA Overview webpage 05/02/07)