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Comparing 2 slopes of 2 regression lines

2 messages · Benedikt Niesterok, PIKAL Petr

Benedikt Niesterok
# 
Hello everyone,
I would like to test two regression slopes:do they differ significantly?The data and commands I've used so far:
x<-8.5:32.5   #Vektor x
y<-c(   NA ,  NA , 5.67 , 6.53 , 6.83,  7.41 , 7.93 ,  8.5 , 8.86,  9.46 , 9.82 ,   10 ,10.35 , 10.7 ,11.03 ,11.37 ,11.61 ,11.84, 12.12, 12.39 ,12.67 ,12.96, 13.28 ,13.47, 13.65) #Vektor y

(regression<-lm(y~x))
summary(regression)   Regression model 1

x<-8.5:32.5   #Vektor x
y<-c(  NA, 5.88  ,6.95 ,  7.2  ,7.66 , 8.02,  8.44,  9.06 , 9.65, 10.22 ,10.63, 11.06, 11.37, 11.91, 12.28 ,12.69 ,13.07 , 13.5 , 13.3 ,14.14 ,   NA  ,  NA  ,  NA  ,  NA   , NA) #Vektor y

(regression<-lm(y~x))
summary(regression)     Regression model 2

Now I don't know how to continue as I want to test the slopes only ,not the regression lines in total.

Another problem I have is rather a formal one:
y<-c(   NA ,  NA , 5.67 , 6.53 , 6.83,  7.41 , 7.93 ,  8.5 , 8.86,  9.46 , 9.82 ,   10 ,10.35 , 10.7 ,11.03 ,11.37 ,11.61 ,11.84, 12.12, 12.39 ,12.67 ,12.96, 13.28 ,13.47, 13.65) #Vektor y

that is my y-vector; I always need to copy and paste this line originating
from:
      X8.5 X9.5 X10.5 X11.5 X12.5 X13.5 X14.5 X15.5 X16.5 X17.5
SD24   NA   NA  5.67  6.53  6.83  7.41  7.93   8.5  8.86  9.46

      X18.5 X19.5 X20.5 X21.5 X22.5 X23.5 X24.5 X25.5 X26.5 X27.5 X28.5 
       9.82    10 10.35  10.7 11.03 11.37 11.61 11.84 12.12 12.39 12.67

      X29.5 X30.5 X31.5 X32.5
       12.96 13.28 13.47 13.65
R always considers the original data as different variables(as matrix).
I already tried: y<-as.vector(SD24)
It doesn't work.   SD24 is the object giving me the original data you see.


sorry for writing so long; hope it is clear what I wrote.

Thanks for your efforts,   Benedikt

--
PIKAL Petr
# 
Hi

r-help-bounces at r-project.org napsal dne 06.04.2009 12:28:35:
significantly?The
, 9.
,12.
,10.
,
the
Here is one approach
http://tolstoy.newcastle.edu.au/R/e6/help/09/01/2632.html
, 9.
,12.
originating
You probably read SD24 from some source by read.delim which suppose the 
first line is header and subsequent lines (in your case only one) are 
data.

I would try to read it with header = FALSE option. You shall get data 
frame with 2 lines and you could then use

t(your.reed.data)

to transpose it to more convenient form.

Or you can use
x <- your.read.data[1,]
y <- your.read.data[2,]

to get x, y.

Regards
Petr
see.
http://www.R-project.org/posting-guide.html