The relationship here means: the occurrence of one time series increase(boost) or decrease(suppress) the values of another time series.
Is there any statistical model or method that can do this kind of task?
Specifically, I have two time series, which is the number of retweets of two different memes(hashtags) at different time. I want to know if the existence of one meme has some influence on the other meme? The influence can be promoting the other one or suppressing.
I did find a model in ecology, which is the Lotka–Volterra equations. But it seems it does not provide a effective algorithm to determine this types of relationship.