Re: [R] Histogram to KDE

2012-09-06 Thread Tim Hesterberg
To bootstrap from a histogram, use
  sample(bins, replace = TRUE, prob = counts)

Note that a kernel density estimate is biased, so some bootstrap
confidence intervals have poor coverage properties.
Furthermore, if the kernel bandwidth is data-driven then the estimate
is not functional, so some bootstrap and jackknife methods won't work right.

Tim Hesterberg
http://www.timhesterberg.net
New:  Mathematical Statistics with Resampling and R, Chihara  Hesterberg

On Fri, Aug 31, 2012 at 12:15 PM, David L Carlson dcarl...@tamu.edu wrote:

 Using a data.frame x with columns bins and counts:

 x - structure(list(bins = c(3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, 10.5,
 11.5, 12.5, 13.5, 14.5, 15.5), counts = c(1, 1, 2, 3, 6, 18,
 19, 23, 8, 10, 6, 2, 1)), .Names = c(bins, counts), row.names =
 4:16,
 class = data.frame)

 This will give you a plot of the kde estimate:


Thanks.


 xkde - density(rep(bins, counts), bw=SJ)
 plot(xkde)

 As for the standard error or the confidence interval, you would probably
 need to use bootstrapping.



 On a similar note - is there a way in R to directly resample /
cross-validate from a histogram of a data-set without recreating the
original data-set ?


   -Original Message-
 
  Hello,
  I wanted to know if there was way to convert a histogram of a data-set
  to a
  kernel density estimate directly in R ?
 
  Specifically, I have a histogram [bins, counts] of samples {X1 ...
  XN} of a quantized variable X where there is one bin for each level of
  X,
  and I'ld like to directly get a kde estimate of the pdf of X from the
  histogram. Therefore, there is no additional quantization of X in the
  histogram. Most KDE methods in R seem to require the original sample
  set   - and I would like to avoid re-creating the samples from the
  histogram. Is there some quick way of doing this using one of the
  standard
  kde methods in R ?
 
  Also, a general statistical question - is there some measure of the
  standard error or confidence interval or similar of a KDE of a data-set
  ?
 
  Thanks,
  -fj
 


   [[alternative HTML version deleted]]

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Re: [R] Histogram to KDE

2012-09-05 Thread firdaus.janoos
On Fri, Aug 31, 2012 at 12:15 PM, David L Carlson dcarl...@tamu.edu wrote:

 Using a data.frame x with columns bins and counts:

 x - structure(list(bins = c(3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, 10.5,
 11.5, 12.5, 13.5, 14.5, 15.5), counts = c(1, 1, 2, 3, 6, 18,
 19, 23, 8, 10, 6, 2, 1)), .Names = c(bins, counts), row.names =
 4:16,
 class = data.frame)

 This will give you a plot of the kde estimate:


Thanks.


 xkde - density(rep(bins, counts), bw=SJ)
 plot(xkde)

 As for the standard error or the confidence interval, you would probably
 need to use bootstrapping.



 On a similar note - is there a way in R to directly resample /
cross-validate from a histogram of a data-set without recreating the
original data-set ?


   -Original Message-
 
  Hello,
  I wanted to know if there was way to convert a histogram of a data-set
  to a
  kernel density estimate directly in R ?
 
  Specifically, I have a histogram [bins, counts] of samples {X1 ...
  XN} of a quantized variable X where there is one bin for each level of
  X,
  and I'ld like to directly get a kde estimate of the pdf of X from the
  histogram. Therefore, there is no additional quantization of X in the
  histogram. Most KDE methods in R seem to require the original sample
  set   - and I would like to avoid re-creating the samples from the
  histogram. Is there some quick way of doing this using one of the
  standard
  kde methods in R ?
 
  Also, a general statistical question - is there some measure of the
  standard error or confidence interval or similar of a KDE of a data-set
  ?
 
  Thanks,
  -fj
 


[[alternative HTML version deleted]]

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[R] Histogram to KDE

2012-08-31 Thread firdaus.janoos
Hello,
I wanted to know if there was way to convert a histogram of a data-set to a
kernel density estimate directly in R ?

Specifically, I have a histogram [bins, counts] of samples {X1 ...
XN} of a quantized variable X where there is one bin for each level of X,
and I'ld like to directly get a kde estimate of the pdf of X from the
histogram. Therefore, there is no additional quantization of X in the
histogram. Most KDE methods in R seem to require the original sample
set   - and I would like to avoid re-creating the samples from the
histogram. Is there some quick way of doing this using one of the standard
kde methods in R ?

Also, a general statistical question - is there some measure of the
standard error or confidence interval or similar of a KDE of a data-set ?

Thanks,
-fj

[[alternative HTML version deleted]]

__
R-help@r-project.org mailing list
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and provide commented, minimal, self-contained, reproducible code.


Re: [R] Histogram to KDE

2012-08-31 Thread David L Carlson
Using a data.frame x with columns bins and counts:

x - structure(list(bins = c(3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, 10.5, 
11.5, 12.5, 13.5, 14.5, 15.5), counts = c(1, 1, 2, 3, 6, 18, 
19, 23, 8, 10, 6, 2, 1)), .Names = c(bins, counts), row.names =
4:16,
class = data.frame)

This will give you a plot of the kde estimate:

xkde - density(rep(bins, counts), bw=SJ)
plot(xkde)

As for the standard error or the confidence interval, you would probably
need to use bootstrapping. 

--
David L Carlson
Associate Professor of Anthropology
Texas AM University
College Station, TX 77843-4352

 -Original Message-
 From: r-help-boun...@r-project.org [mailto:r-help-bounces@r-
 project.org] On Behalf Of firdaus.janoos
 Sent: Friday, August 31, 2012 9:52 AM
 To: r-help@r-project.org
 Subject: [R] Histogram to KDE
 
 Hello,
 I wanted to know if there was way to convert a histogram of a data-set
 to a
 kernel density estimate directly in R ?
 
 Specifically, I have a histogram [bins, counts] of samples {X1 ...
 XN} of a quantized variable X where there is one bin for each level of
 X,
 and I'ld like to directly get a kde estimate of the pdf of X from the
 histogram. Therefore, there is no additional quantization of X in the
 histogram. Most KDE methods in R seem to require the original sample
 set   - and I would like to avoid re-creating the samples from the
 histogram. Is there some quick way of doing this using one of the
 standard
 kde methods in R ?
 
 Also, a general statistical question - is there some measure of the
 standard error or confidence interval or similar of a KDE of a data-set
 ?
 
 Thanks,
 -fj
 
   [[alternative HTML version deleted]]
 
 __
 R-help@r-project.org mailing list
 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.

__
R-help@r-project.org mailing list
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.