r-sig-ecology-boun...@r-project.org wrote on 06/24/2009 10:25:25 PM:
> [image removed]
>
> Re: [R-sig-eco] Log transforming zero value data
>
> Nate Upham
>
> to:
>
> Ben Bolker
>
> 06/25/2009 06:39 AM
>
> Sent by:
>
> r-sig-ecology-boun
regression.
regards,
David
r-sig-ecology-boun...@r-project.org wrote on 06/24/2009 10:25:25 PM:
> [image removed]
>
> Re: [R-sig-eco] Log transforming zero value data
>
> Nate Upham
>
> to:
>
> Ben Bolker
>
> 06/25/2009 06:39 AM
>
> Sent by:
>
&
pecific impacts of the habitat variable on average densities in Y?
Thanks,
--Nate
Original message
>Date: Wed, 24 Jun 2009 21:25:36 -0400
>From: Ben Bolker
>Subject: Re: [R-sig-eco] Log transforming zero value data
>To: Nate Upham
>Cc: "r-sig-ecology@r-project.org
;Date: Wed, 24 Jun 2009 17:13:07 -0400
>From: Ben Bolker
>Subject: Re: [R-sig-eco] Log transforming zero value data
>To: Nate Upham
>Cc: Matthew Landis , "r-sig-ecology@r-project.org"
>
> If you have percentage abundances (i.e. you can specify the
>"denomi
Hi Nate,
Here is my 2 cents worth after coming in late to this discussion.
The fact that your data are proportions is important as it suggests how
the data may vary. Do you have the numerator and denominator used to
calculate the proportions? If so then I would suggest that you should be
perf
Thanks very much indeed Carsten and Philippe!
Lots to consider. I should have specified this before, but the
variable with zero values that I would like to log (ln) transform does
consist of many small values. The range is between 0.00 and 0.35,
since this variable is the percentage abundan
Many thanks to Carsten, Philippe, and Nate for a very informative and
entertaining discussion of something I have always wondered about,
having heard suggestions for both approaches. At least now I have a
better understanding of the rationale for each!
Matt
M
Dear Philippe,
while I don't like to quibble about rules-of-thumb (since they are, as
you rightly point out, without foundation in statistical theory), I
would like to correct the impression that you gave in your email.
Let's take an hypothetical example along the lines you proposed (or at
lea
Carsten Dormann wrote:
Dear Nate,
although I learned from Phillippe's response about the existence of
log1p, I don't think I will use it (for reasons below). Thierry's
response is true for Poisson data, but not for non-integer values.
Still, it points into an important direction: All too ofte
Dear Nate,
although I learned from Phillippe's response about the existence of
log1p, I don't think I will use it (for reasons below). Thierry's
response is true for Poisson data, but not for non-integer values.
Still, it points into an important direction: All too often zeros
emanate from a
Verzonden: woensdag 24 juni 2009 2:31
Aan: r-sig-ecology@r-project.org
Onderwerp: [R-sig-eco] Log transforming zero value data
I have a general stats question for you guys:
How does one normally deal with zero (0) values when log transforming
data?
I would like to log transform (natural log, ln
See ?log1p
Best,
Philippe Grosjean
..<°}))><
) ) ) ) )
( ( ( ( (Prof. Philippe Grosjean
) ) ) ) )
( ( ( ( (Numerical Ecology of Aquatic Systems
) ) ) ) ) Mons-Hainaut University, Belgium
( ( ( ( (
...
I have a general stats question for you guys:
How does one normally deal with zero (0) values when log transforming data?
I would like to log transform (natural log, ln) several response variables for
use in quantile
regression. But one of my variables includes several zero values. Since ln(
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