# [R] S: appropriate significance tests

Greg Snow Greg.Snow at imail.org
Wed Oct 20 20:48:28 CEST 2010

```It is not completely clear what question you are trying to answer or what you are trying to accomplish.  But here are some additional questions that may help:

What tests would you use if you could use the original data?
What assumptions are you willing to make about the data and/or statistics?
What are you trying to accomplish?

--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of soeren.vogel at eawag.ch
> Sent: Wednesday, October 20, 2010 7:33 AM
> To: r-help at r-project.org
> Subject: [R] S: appropriate significance tests
>
> Hello
>
> (1) How can I compare two Pearson correlation coefficients for
> significant differences without the use of the raw data?
>
> (2) How can I compare two linear regression coefficients for
> significant differences without the use of the raw data?
>
> (3) How can I compare two multiple correlation coefficients (as
> produced in a linear regression) for significant differences, again, if
> the raw data should not be used?
>
> <src type="perhaps useful">
> da <- data.frame(
>   "y1"=sample(1:5, 40, repl=T),
>   "y2"=sample(1:5, 40, repl=T),
>   "x1"=sample(1:5, 40, repl=T),
>   "x2"=sample(1:5, 40, repl=T)
> )
> cro1 <- cor(da\$y1, da\$x1)
> cro2 <- cor(da\$y2, da\$x1)
> lmo1 <- lm(y1 ~ x1 + x2, data=da)
> lmo2 <- lm(y2 ~ x1 + x2, data=da)
> </src>
>
> Thanks, Sören
>
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