It is easy to forget that the choice of benchmark plays an important role in calculating risk-adjusted performance metrics such as alpha, beta, the information ratio, up/down capture ratios and more.
The S&P500 index (a benchmark for US large cap equity) is the industry-wide default benchmark, but it may not be appropriate for your investments and portfolios. For example, you may prefer a total market index, or a specialized index.
In Portfolio Lab, you can change the index to be used as a benchmark for these ratio calculations.

In the Backtest/Stats view, click on the edit icon (pencil) at the right of the benchmark name, to assign an index of your choice, as show in the red circle above.