Talk:Kumaraswamy distribution

Latest comment: 5 years ago by 124.179.235.21 in topic Errors in PDF & CDF given.


Max likelihood estimates of a and b

edit

Can anyone get the log likelihood estimates of a & b? b as a function of a is pretty easy, but a doesn't seem to have a closed form solution. Martin (talk) 11 November 2006

I think you are right - about the best I can do is this - Define

 
 

Then the likelihood function is

 

and the log likelihood function is

 

The maximum occurs at

 
 

Eliminating b we get

 

Integrating, we get

 

where K is some constant (I think it can be determined). That equation cannot be analytically solved for f(a). If it could, we would still have to substitute that into the defining equation for f(a) and solve for a. PAR 16:57, 11 November 2006 (UTC)Reply

Actually, the best way would be to forget the integration, and match the derivatives instead. The derivative at maximum would be

 

and you would equate that to the derivative of the defining equation for f(a) and solve numerically for a. PAR 23:49, 11 November 2006 (UTC)Reply

the moments

edit

I tried to find the variance of this distribution from the moments given in this paper, but it became negative! Can someone check their accuracy? --Pejman47 (talk) 15:38, 29 June 2008 (UTC)Reply

An example of motivation?

edit

The example lacks any detail that would give it any meaning. — Preceding unsigned comment added by 123.24.215.138 (talk) 01:17, 7 October 2014 (UTC)Reply

Agreed, and more generally, the article needs a description of the process that would give rise to data having a Kumaraswamy distribution. Isambard Kingdom (talk) 02:04, 17 July 2015 (UTC)Reply

Errors in PDF & CDF given.

edit

The pdf and cdf look wrong (even to a casual glance). Not sure what was going on I looked up other references and it seems other sources have a different equation.

eg: [1]

It seems the expression (x − c)/(b − c) occurs often in the pdf/cdf and is given as z = (x − c)/(b − c) for many explanations. This article seems to have erroneously put x instead of z and left out the formula for z.

Anyway, I have no idea how to fix this in wikipedia, so I report the issue here.

124.179.235.21 (talk) 06:58, 20 January 2019 (UTC) What is "Sign your posts on talk pages"Reply

References