[R] threshold distribution

[Mike Lawrence]

You didn't properly specify the x-axis coordinates in your call to lines():

plot(density(x))
lines(x,dlnorm(x, -.1348, .1911), col='red')
points(x,dlnorm(x, -.1348, .1911), col='blue')
curve(dlnorm(x, -.1348, .1911), col='green',add=T)


On Sun, Apr 5, 2009 at 6:40 AM, Bernardo Rangel Tura
<tura at centroin.com.br> wrote:
> On Sun, 2009-04-05 at 01:13 -0400, jim holtman wrote:
>> Here is what I get from using 'fitdistr' in R to fit to a lognormal.
>> The resulting density plot from the distribution seems to be a reason
>> match to the data.
>>
>> > x <- scan()
>> 1: 0.80010 0.72299 0.69893 0.99597 0.89200 0.69312 0.73613 1.13559
>> 9: 0.85009 0.85804 0.73324 1.04826 0.84002
>> 14: 1.76330 0.71980 0.89416 0.89450 0.98670 0.83571 0.73833 0.66549
>> 22: 0.93641 0.80418 0.95285 0.76876 0.82588
>> 27: 1.09394 1.00195 1.14976 0.80008 1.11947 1.09484 0.81494 0.68696
>> 35: 0.82364 0.84390 0.71402 0.80293 1.02873
>> 40:
>> Read 39 items
>> > plot(density(x))
>> > library(MASS)
>> > fitdistr(x, 'lognormal')
>>      meanlog        sdlog
>>   -0.13480636    0.19118861
>>  ( 0.03061468) ( 0.02164785)
>> > lines(dlnorm(x, -.1348, .1911), col='red')
>
> Hi Jim
>
> I agree with your solution but my plot result not fine.
> I obtain same result.
>> fitdistr(x, 'lognormal')
>     meanlog        sdlog
>  -0.13480636    0.19118861
>  ( 0.03061468) ( 0.02164785)
>
> In plot when I use points (blue) and curve (green) the fit o lognormal
> and density(data) is fine but when I use lines (red) the fit is bad (in
> attach I send a PDF of my output)
>
> Do you know why this  happen?
>
> Thanks in advance
>
> --
> Bernardo Rangel Tura, M.D,MPH,Ph.D
> National Institute of Cardiology
> Brazil
>
> P.S. my script is
>
> x <- scan()
> 0.80010 0.72299 0.69893 0.99597 0.89200 0.69312 0.73613 1.13559
> 0.85009 0.85804 0.73324 1.04826 0.84002
> 1.76330 0.71980 0.89416 0.89450 0.98670 0.83571 0.73833 0.66549
> 0.93641 0.80418 0.95285 0.76876 0.82588
> 1.09394 1.00195 1.14976 0.80008 1.11947 1.09484 0.81494 0.68696
> 0.82364 0.84390 0.71402 0.80293 1.02873
>
> require(MASS)
> fitdistr(x, 'lognormal')
> pdf("adj.pdf")
> plot(density(x))
> lines(dlnorm(x, -.1348, .1911), col='red')
> points(x,dlnorm(x, -.1348, .1911), col='blue')
> curve(dlnorm(x, -.1348, .1911), col='green',add=T)
> dev.off()
>
>
>
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>
>



-- 
Mike Lawrence
Graduate Student
Department of Psychology
Dalhousie University

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