[R] qqplot for binomial distribution

[Boris Steipe]

That's not how qqline() works. The line is drawn with respect to a _reference_distribution_ which is the normal distribution by default. For the binomial distribution, you need to specify the distribution argument. There is an example in the help page that shows you how this is done for qchisq(). for qbinom() it is:


set.seed(123)
qqplot(rbinom(n=100, size=100, p=0.05), 
       rbinom(n=100, size=100, p=0.05) )
 
qqline(rbinom(n=100,size=100,p=.05),
       distribution = function(probs) { qbinom(probs, size=100, prob=0.05) },
       col = "red",
       lwd = 0.5)




B.


> On Apr 17, 2017, at 9:15 AM, Ashim Kapoor <ashimkapoor at gmail.com> wrote:
> 
> Dear Spencer,
> 
> Okay. Many thanks. My next query is how do I use qqline?
> 
> When I try
> 
>> qqline(rbinom(n=100,size=100,p=.05))
> 
> I don't get the line in the right place.
> 
> Best Regards,
> Ashim
> 
> On Mon, Apr 17, 2017 at 6:31 PM, Spencer Graves <
> spencer.graves at effectivedefense.org> wrote:
> 
>> 
>> 
>> On 2017-04-17 7:58 AM, Ashim Kapoor wrote:
>> 
>>> Dear All,
>>> 
>>> set.seed(123)
>>> qqplot(rbinom(n=100,size=100,p=.05), rbinom(n=100,size=100,p=.05) )
>>> 
>>> I expect to see 1 clear line,but I don't. What am I misunderstanding?
>>> 
>> 
>> 
>>      The distribution is discrete, and points are superimposed. Try the
>> following:
>> 
>> 
>> set.seed(123)
>> qqplot(jitter(rbinom(n=100,size=100,p=.05)),
>>       jitter(rbinom(n=100,size=100,p=.05) ))
>> 
>> 
>>      Spencer Graves
>> 
>>> 
>>> Best Regards,
>>> Ashim
>>> 
>>>        [[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/posti
>>> ng-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>> 
>> 
>> ______________________________________________
>> 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/posti
>> ng-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>> 
> 
> 	[[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.