It has values between zero and infinity. It can be used to rank the
performance of portfolios. The lower the d ratio the better the
performance, a value of zero indicating there are no returns less than
zero and a value of infinity indicating there are no returns greater than zero.
$$DRatio(R) = \frac{n_{d}*\sum^{n}_{t=1}{max(-R_{t},0)}}{n_{u}*\sum^{n}_{t=1}
{max(R_{t},0)}}$$
where \(n\) is the number of observations of the entire series,
\(n_{d}\) is the number of observations less than zero,
\(n_{u}\) is the number of observations greater than zero