R help - Apr 2016 - Problem: No p-value for a point-baserial correlation with R

Dear community
 
I'm pretty new to R and I'm trying to do a Point-baserial correlation
for a nominal dichotomous variable with a interval scaled variable. It works
fine, but the output just shows me the correlation and nothing else (p-Value
would be important).
 
I tried it with the following codes:
 
- biseral.cor()
- cor.biseral()
- I also tried a polyserial() I've found on this question page:
http://stackoverflow.com/questions/35880910/point-biserial-and-p-value
Problem: It's not working (telling me y has fewer than 2 levels) and it
would also be for a ordinal dichotomous variable, but I only have a nominal
dichotomous variable.
 
In the forum if found following Syntax that I've tried out:
https://stat.ethz.ch/pipermail/r-help/2003-April/031852.html
It seams to work because I don't get any error messages but I'm not
getting an output either.
 
I'm really thankful for every help I could get on this topic or tips where I
can find out and learn how to find a correlation with a p-value in R for a
nominal dichotomous and an interval scaled variable.
Thanks in advance and have a nice weekend!
 		 	   		  
	[[alternative HTML version deleted]]

Dear Dominik,

There's not enough information here to answer your question: You don't
show the commands you used, nor the output that was produced, and you don't
share your data. A good guess, however, is that there is only one level of the
factor, perhaps after missing data are removed, and so it's not possible to
compute a biserial correlation.

By the way, if the dichotomous factor is really nominal, then it doesn't
make sense to compute a biserial correlation, which assumes that there's a
latent continuous and normally distributed variable that has been dichotomized
at an unknown threshold.

Best,
 John

-----------------------------
John Fox, Professor
McMaster University
Hamilton, Ontario
Canada L8S 4M4
web: socserv.mcmaster.ca/jfox


________________________________________
From: R-help [r-help-bounces at r-project.org] on behalf of Dominik Maiori
[d.maiori at windowslive.com]
Sent: April 16, 2016 5:39 AM
To: r-help at r-project.org
Subject: [R] Problem: No p-value for a point-baserial correlation with R

Dear community

I'm pretty new to R and I'm trying to do a Point-baserial correlation
for a nominal dichotomous variable with a interval scaled variable. It works
fine, but the output just shows me the correlation and nothing else (p-Value
would be important).

I tried it with the following codes:

- biseral.cor()
- cor.biseral()
- I also tried a polyserial() I've found on this question page:
http://stackoverflow.com/questions/35880910/point-biserial-and-p-value
Problem: It's not working (telling me y has fewer than 2 levels) and it
would also be for a ordinal dichotomous variable, but I only have a nominal
dichotomous variable.

In the forum if found following Syntax that I've tried out:
https://stat.ethz.ch/pipermail/r-help/2003-April/031852.html
It seams to work because I don't get any error messages but I'm not
getting an output either.

I'm really thankful for every help I could get on this topic or tips where I
can find out and learn how to find a correlation with a p-value in R for a
nominal dichotomous and an interval scaled variable.
Thanks in advance and have a nice weekend!

        [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Hi Dominik
Welcome to R-help 

Please have a look at
http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
and/or http://adv-r.had.co.nz/Reproducibility.html for some suggestions on how
to ask questions here.

In particular we probably need to know what packages have the biseral.cor()
& cor.biseral() functions and some sample data.

Read the part about dput() carefully. This is the best way to provide sample
data to R-help.

BTW try a str(mydata) and check to see that you have the factor levels you think
you do.

John Kane
Kingston ON Canada

> -----Original Message-----
> From: d.maiori at windowslive.com
> Sent: Sat, 16 Apr 2016 11:39:47 +0200
> To: r-help at r-project.org
> Subject: [R] Problem: No p-value for a point-baserial correlation with R
> 
> Dear community
> 
> I'm pretty new to R and I'm trying to do a Point-baserial
correlation for
> a nominal dichotomous variable with a interval scaled variable. It works
> fine, but the output just shows me the correlation and nothing else
> (p-Value would be important).
> 
> I tried it with the following codes:
> 
> - biseral.cor()
> - cor.biseral()
> - I also tried a polyserial() I've found on this question page:
> http://stackoverflow.com/questions/35880910/point-biserial-and-p-value
> Problem: It's not working (telling me y has fewer than 2 levels) and it
> would also be for a ordinal dichotomous variable, but I only have a
> nominal dichotomous variable.
> 
> In the forum if found following Syntax that I've tried out:
> https://stat.ethz.ch/pipermail/r-help/2003-April/031852.html
> It seams to work because I don't get any error messages but I'm not
> getting an output either.
> 
> I'm really thankful for every help I could get on this topic or tips
> where I can find out and learn how to find a correlation with a p-value
> in R for a nominal dichotomous and an interval scaled variable.
> Thanks in advance and have a nice weekend!
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
____________________________________________________________
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