Dear Steven,
Your xlim() function is what changes the behavior of the x axis values; If you remove the xlim()
statement from your function, you get a "correct" x axis:
##
YC=82:91
Age=rev(seq(2,11,1))
Num=c(2,0,8,21,49,18,79,28,273,175)
box44=data.frame(YC,Age,Num)
mod1=lm(log(Num+1)~YC, data=box44)
plot(log(Num+1)~YC, data=box44, pch=19, xlab="Year Class",
ylab="Loge Number at age", ylim=c(0,6))
abline(lm(log(Num+1)~YC), col="blue", lwd=2)
##
But what kind of graph do you want to arrive at in the end?
Best wishes
Christoph
Ranney, Steven schrieb:
I have data that looks like
YC Age Num
82 11 2
83 10 0
84 9 8
85 8 21
86 7 49
87 6 18
88 5 79
89 4 28
90 3 273
91 2 175
with a program
mod1=lm(log(Num+1)~YC, data=box44)
plot(log(Num+1)~YC, data=box44, pch=19, xlab="Year Class",
ylab="Loge Number at age", ylim=c(0,6), xlim=c(91,82))
abline(lm(log(Num+1)~YC), col="blue", lwd=2)
summary(mod1)
I need to regress log(Num+1) against YC, but in descending (91 - 82) order so
as to get a negative slope and positive intercept. I can plot the values such
that the regression line appears correct (the xlim statement), but I can't
figure out how to force the regression from YC 91 through 82. A call to the
rev() function in front of YC does not produce the results I'm looking for.
More than likely, I'm overlooking something. Thanks for any help you can
provide.
SR
Steven H. Ranney
Graduate Research Assistant (Ph.D)
USGS Montana Cooperative Fishery Research Unit
Montana State University
PO Box 173460
Bozeman, MT 59717-3460
phone: (406) 994-6643
fax: (406) 994-7479
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--
Dr. rer.nat. Christoph Scherber
University of Goettingen
DNPW, Agroecology
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