This script is a revised version of jchang274's script.
The percentage of stocks trading above a specific moving average is a breadth indicator that measures internal strength or weakness in the underlying index. The 50-day moving average is used for short-to-medium-term timeframes. Signals can be derived from overbought/oversold levels, crosses above/below 50% and bullish / bearish divergences.
Breadth is weakening when the indicator falls and strengthening when the indicator rises. A rising market and falling indicator would raise suspicions on underlying weakness. Similarly, a falling market and rising indicator would suggest underlying strength that could foreshadow a bullish reversal.