# Autocorrelation vs correlation calculation

I have set $x = {1,2,3,4,5}$ and set $y = {2,3,4,5,6}$. Lets say the correlation of $x$ and $y$ is $0.7$. If I then have set $z = {1,2,3,4,5,2,3,4,5,6}$, and I do autocorrelation using lag $=$ $5$, should I not get the same $0.7$? I have been doing this but I keep getting different results. I'm wondering if I'm doing something wrong, or maybe it is that they should have different results.

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The first question is probably answered at stats.stackexchange.com/q/10947 . –  whuber Jun 2 '11 at 3:13
Thanks guys that answers question one. –  solartic Jun 2 '11 at 4:02