You can check easily for linear correlation using Spearman or Pearson correlation. I think the easier way to check for correlation is to plot one parameter against the other, then you can visualy check the correlation between the two of them and choose the appropiate test (if you need that).

Cheers

Hi Antonio, thanks for your response. I have a bit different question. In the graph , the correlation is only true for the part where both intensity decrease. and the dip in one curve is before and faster than other, so direct linear correlation is not feasible. I was hoping of some methodology to correlate the dip in both cases.

Thanks

Kapish

Dear Kapish,

before calculating Spearman or Pearson correlation factors, you may center and reduce the variables (normalisation). By doing so, you will get more comparable curves. Alternately, you may also substract an estimate of the tendency of your curves (see Theil-Sen estimator for example).

Additionally, if you want to synchronise your curves in order to correlate the dips, you may use DTW (Dynamic-Time Warping).

Hope it helps,

Pierre