Indexing and active management may seem like opposite sides in a debate. For some investors, if one strategy is right, the other must be wrong. In reality, combining the two very different approaches to portfolio construction can add value.Broad-market index funds combine diversification with low cost, a strategy that has historically outperformed most actively managed funds. On the other hand, because active manages veer from the market-cap weightings typical of most indexes, they provide the opportunity of out performance in their benchmarks, as well as the risk of lagging them.Under the right circumstances, active and passive components can complement each …