Correlation As A Trend Indicator by John F. Ehlers
Here, we introduce a new indicator: the correlation trend indicator. It could help you to identify the onset of a trend. It could also help you to detect the failure of a trend thereby giving you an indication that a cyclic mode may be beginning.
While the concept is straightforward, I have not seen a description of using correlation directly as an indicator. How would this work? Imagine correlating prices with a straight line having a positive slope. If the price trend is up, the correlation is nearly +1 ...