Hello, This is not a purely R-question, but perhaps someone can help me anyway. I am trying to estimate the correlation between two time series (which are both basically different types of measurements of the same phenomena), using both cor.test() (with pearson as method) and ccf(). Now, cor.test gives a confidence interval for the pearson correlation, while ccf does not. I've tried to use bootstrap methods to get confidence interval for the ccf function, but no luck. It is a bit tricky, since the time series are non-stationary, and so I'm not sure how to go about to generate the bootstrap-sample. Does anyone have any ideas on how to do this, i.e get a confidence interval for the ccf at different time lags? Many thanks in advance, Gustaf -- Gustaf Rydevik, M.Sci. tel: +46(0)703 051 451 address:Essingetorget 40,112 66 Stockholm, SE skype:gustaf_rydevik