I am seeking to characterize time-series data (specifically parameters derived from sensor data) for 18 patients collected over 20 days using autocorrelation (see plot below of autocorrelation functions for 18 patients for a given sensor parameter).
I want to see if I can use the autocorrelation function values at different lag values (days in this case) to distinguish between time-series.
Is correlating the autocorrelation value at a given lag with another parameter (e.g. patient age or patient outcome measure) a statistically valid approach?
Can autocorrelation be used to infer the statistical relationship between day-to-day measurements of the sensor data?