# How would I interpret this PACF and ACF graph?

I was thinking, from the ACF it looks like a nonstationary process. Or is it an AR process? From the PACF, does that mean it is AR(1)? There are 2 significant spikes in the PACF. I'm confused.

• what sort of data is it on? – Jan Sila Oct 18 '16 at 8:39
• it is a time series data of a commodity price (natural log of real prices not nominal). Its sugar – user7035336 Oct 18 '16 at 9:20

In terms of PACF, it suggests what is the order of autocorrelation in the series, but in this case the spike is at 10th and personally, I would assume that AR(1) with $x_{t-10}$ won't really explain much. But it depends what sort of data is it on, maybe it makes sense...
• Generally noninteger values on the $x$-axis are not a problem. This could be monthly data with a period of 12, then a 1 on the axis stands for 1 year. Also, why long memory? Looks like ACF has an exponential (rather than linear) decay, hence short memory. – Richard Hardy Oct 18 '16 at 8:52