Hi everyone,

i don't get the qqplot which is used to test if the sample followed a t-distribution? 

qqplot(qt(ppoints(z), df = 7.6), z, xlab = "Q-Q plot for t dsn")
qqline(z)

what qt() means? what ppoints() means? 

I know qqnorm() will plots the data in the way of normal distribution. how to make the qqplot to plot the data in the form of t-distribution? 

Or is there any command can actually test if the imput data is t-distribution? like the shapiro.test(x) used to test the normality. 


Thank you so much, guys. 


Sincerely,


Bill

----- Original Message -----
From: Michael Bedward <michael.bedward@gmail.com>
Date: Friday, December 3, 2010 7:48 pm
Subject: Re: [R] testing and ploting t-distribution
To: 5qy@queensu.ca
Cc: r-help@r-project.org

> Hello Bill,
> 
> Have a look at the example at the bottom of the help page for ?qqplot
> 
> Michael
> 
> 
> On 4 December 2010 11:19,  <5qy@queensu.ca> wrote:
> > Hi there,
> >
> >
> > I am doing a test to see the the residual is distributed in 
> the form of t-distribution and trying to plot the residuals and 
> the t-distribution to compare in the graph.
> >
> > Cheers,
> >
> > Bill
> >
> >
> >
> > ----- Original Message -----
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