Message-ID: <A237B6F2-FFCA-443F-B418-468F0F3429DB@me.com>
Date: 2009-12-30T02:09:58Z
From: donahchoo at me.com
Subject: histogram, sd and mean questions
Hi,
I'm trying to plot the histogram, sd and mean of some range data I
have collected and I have several questions. First off, my statistics
is ancient at best, so if I get things wrong forgive me.
What I'm trying to do is determine the range of the YM for 30 minute
periods throughout the day. I've got the code the determining range
working, but my standard deviation plots appear to be off.
In the graph below the orange dotted line is the mean and the dotted
red lines are +/- 1sd. What I want to determine what ranges are
within 1 sd of the mean and this graph looks off to me.
Can anyone confirm that I have (not) done this correctly? Is there a
way I can get a finer scale on the x axis? So far I haven't found a
way to set tick marks on the charts...
Here's my R code:
> hist(range_tmp, breaks=250, xlim=c(0,250))
> abline(v=mean(range_tmp), col='orange', lty=2, lwd=2.5)
> abline(v=mean(range_tmp) + sd(range_tmp), col='red', lty=2, lwd=2.5)
> abline(v=mean(range_tmp) - sd(range_tmp), col='red', lty=2, lwd=2.5)
Thanks!
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