Granger Causality

TL;DR for operators Signals do not always influence each other on one clock. A machine vibration may create a fast alarm signature and a slower thermal drift. A brain region may interact through one rhythm quickly and another rhythm slowly. A market signal may move through intraday noise, weekly positioning, and slower macro repricing. Treating all of that as one blended time series is convenient. It is also a rather efficient way to throw away the thing you wanted to understand. ...

TL;DR for operators Volatility is usually treated as a risk input: measure it, size positions around it, and try not to get mugged by it before lunch. This paper treats volatility differently. It uses mid-range volatility to select stocks that are neither comatose nor explosive, then applies a causal-inference stack to find which stocks appear to move before others. ...