Re: [R] ANOVA non-sphericity test and corrections (eg, Greenhouse-Geisser)

2007-06-25 Thread John Wilkinson

Darren,

Further to Peter Dalgaard's help;

Take a look at the example in ---

library(car)
?Anova  # note upper case 'A' 

The example in the Anova help page following the ---

## a multivariate linear model for repeated-measures data
## See ?OBrienKaiser for a description of the data set used in this example

gives a workings for --

## Greenhouse-Geisser and Huynh-Feldt Corrections
##  for Departure from Compound Symmetry

You might find that example helpful.

John

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Re: [R] extracting the mode of a vector

2007-04-23 Thread John Wilkinson


Beno?t L?t? wrote:
 Hello,

 I have an elementary question (for which I couldn't find the answer on the
 web or the help): how can I extract the mode (modal score) of a vector?

Assuming that your vector contains only integers:

  v - sample(1:5, size=20, replace=T)
  v
  [1] 1 1 1 1 2 3 5 1 1 5 2 4 1 3 1 1 5 4 1 5
  vt - table(v)
  as.numeric(names(vt[vt == max(vt)]))
[1] 1
 

Cheers,
Gad

#
or more succinctly,

 names(vt[which.max(vt)])
[1] 1

John

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Re: [R] ordering boxplots according to median

2006-03-22 Thread John Wilkinson (pipex)

Use reorder 

# boxplot with increasing order of medians
 
s2-with(InsectSprays,reorder(spray,count,median))
 with(InsectSprays,boxplot(count~s2))

# boxplot with decreasing order of medians

s2-with(InsectSprays,reorder(spray,-count,median))
 with(InsectSprays,boxplot(count~s2))

John

Talloen, Willem wrote--
Dear R-users,

Does anyone knows how I can order my serie of boxplots from lowest to
highest median (which is much better for visualization purposes).

thanks in advance,
willem



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Re: [R] How to find statistics like that.

2005-11-11 Thread John Wilkinson \(pipex\)
Adai,

I recently came across the following definition of a statistic
which may be relevent to the discussion.

John
-

Beran’s (2003) provocative definition of statistics as “the study of
algorithms for data analysis” elevates computational considerations to the
forefront of the field. It is apparent that the evolutionary success of
statistical methods is to a significant degree determined by considerations
of computational convenience. As a result,design and dissemination of
statistical software has become an integral part of statistical research.

from this it follows that a 'Statistic' is

  A mathematical function or  algorithm for data analysis



Duncan Murdoch wrote


On 11/9/2005 10:01 PM, Adaikalavan Ramasamy wrote:
 I think an alternative is to use a p-value from F distribution. Even
 tough it is not a statistics, it is much easier to explain and popular
 than 1/F. Better yet to report the confidence intervals.

Just curious about your usage:  why do you say a p-value is not a statistic?

Duncan Murdoch

Adaikalavan Ramasamy replied
-

If my usage is wrong please correct me. Thank you.

Here are my reason :

1. p-value is a (cumulative) probability and always ranges from 0 to 1.
A test statistic depending on its definition can wider range of possible
values.

2. A test statistics is one that is calculated from the data without the
need of assuming a null distribution. Whereas to calculate p-values, you
need to assume a null distribution or estimate it empirically using
permutation techniques.

3. The directionality of a test statistics may be ignored. For example a
t-statistics of -5 and 5 are equally interesting in a two-sided testing.
But the smaller the p-value, more evidence against the null hypothesis.

Regards, Adai

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Re: [R] Extracting Variance Components

2005-10-27 Thread John Wilkinson \(pipex\)
Mike,

use ---

VarCorr(lme.object)

or for a user friendly output use varcomp from the 'ape' package--

require(ape)
varcomp(lme.object)

varcomp also allows scaling of components to unity (*100 gives %)
and also allows for cumulative sum of components.

Note. varcomp doesn't work for lmer objects.

HTH,

John
--

Michel Friesenhahn wrote-
 
Dear List,

Is there a way to extract variance components from lmeObjects or 
summary.lme objects without using intervals()?  For my purposes I don't 
need the confidence intervals which I'm obtaining using parametric 
bootstrap.

Thanks,

Mike

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Re: [R] lme and lmer syntax

2005-10-26 Thread John Wilkinson \(pipex\)
Ronaldo,

According to Douglas Bates's paper in 'R' News, It would seem that the
correct model for nested split plot random effects with lmer , in your
example ,with x2 nested within x1, would be --

lmer(y~x1 + x2 +(1|x1)+(1|x1:x2))

Try it with your model any see how it compares with your aov and lme models,

John


m Seg 24 Out 2005 18:08, Doran, Harold escreveu:
 Ronaldo

 See the article on lmer pasted below for syntax. It is the only current
 source documenting the code. In lmer(), the nesting structure for the
 ranmdom effects is handled in a slightly different way. If your
 observations are nested as you note, then you can use

  lmer(y~x1 + x2 +(1|x1) + (1|x2), data)

 @Article{Rnews:Bates:2005,
   author   = {Douglas Bates},
   title  = {Fitting Linear Mixed Models in {R}},
   journal  = {R News},
   year   = 2005,
   volume   = 5,
   number   = 1,
   pages  = {27--30},
   month  = {May},
   url= {http://CRAN.R-project.org/doc/Rnews/},
 }


Hi,

I try this with a splitsplitplot example.

I make the correct model with aov, lme do compare with lmer.

But I cant make a correct model in lmer. Look that the aov and lme results
are
similars, but very different from lmer. In aov and lme is used the correct
DF
for each variable, in lmer it use a same DF for all? Denom=54.

What is my mistake?

Thanks
Ronaldo

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Re: [R] Subsetting a list

2005-10-19 Thread John Wilkinson \(pipex\)
Dennis 

Try 

  TEST[-3]
[[1]]
[1] A1 A2

[[2]]
[1] B1 B2

for removing more than one element from the list (say 2  3) --

 TEST[-c(2,3)]
[[1]]
[1] A1 A2

HTH

John

Dennis Fisher wrote---

Colleagues,

I have created a list in the following manner:
 TEST- list(c(A1, A2), c(B1, B2), c(C1, C2))

I now want to delete one element from the list, e.g., the third.  The  
command
 TEST[[3]]
yields (as expected):
 [1] C1 C2

The command
 TEST[[-3]]
yields:
 Error: attempt to select more than one element

How can I accomplish delete one or more elements from this list?

I am running R2.2.0 on a Linux platform.

Dennis

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Re: [R] Sorting a data frame by one of the variables

2005-10-16 Thread John Wilkinson \(pipex\)
Leaf,

using your example data as 'dat' below --

 dat-read.table(clipboard,header=T)
 dat
 XYZ
1 22.0 24.0  4.3
2  2.3  3.4  5.3
3 57.2 23.4 34.0

#to order the data frame by say X (for column 1)--

dat1-dat[order(dat[,1]),]
 dat1
 XYZ
2  2.3  3.4  5.3
1 22.0 24.0  4.3
3 57.2 23.4 34.0


By way of interest if you wanted to order EVERY  column
in ascending order then you could do a loop ---

# to order  all cols of dat by rows (ascending)

dat2-dat
 for (i in 1:3) dat2[,i]-dat[order(dat[,i]),i]
 dat2
 XYZ
1  2.3  3.4  4.3
2 22.0 23.4  5.3
3 57.2 24.0 34.0


I hope that helps,

John


=
Leaf Sun wrote---

Dear all,

I have a date frame like this:

X   Y   Z
22  24  4.3
2.3 3.4 5.3
.

57.223.434

What my purpose is: to sort the data frame by either X, Y or Z.
sample output is (sorted by X) :

X   Y   Z
2.3  3.4  5.3
.
..
22 24  4.3
...
57.2  23.4  34

I have no idea how to use sort, order or rank functions. Please help me out.
Thanks!

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Re: [R] Doubt about nested aov output

2005-09-07 Thread John Wilkinson \(pipex\)
Ronaldo ,

It looks as though you have specified you model incorrectly.

In the Rats example ,the Treatment is the only fixed effect,Rat and Liver
are random effects

In aov testing for sig of 'Means' of Random Effects is pointless and that is
why 'p' values are not given.Further more the interaction between a Random
Effect and a Fixed Effect is also a Random Effect. The 'aov' with error
structure terms output reflects this by only giving 'p' values to
Fixed Effects and their interactions.



Note That the Fixed Effects of Block, Variety and their interaction
Block:Variety are given p values while the Field'Random Effects have not.



  model - aov(Glycogen~Treatment+Error(Rat/Liver))
 summary(model)

Error: Rat
  Df Sum Sq Mean Sq F value Pr(F) #Rat is random effect
Residuals  1 413.44  413.44

Error: Rat:Liver  #Rat:Liver is Random 
effect
  Df  Sum Sq Mean Sq F value Pr(F)
Residuals  4 164.444  41.111

Error: Within
  Df  Sum Sq Mean Sq F valuePr(F)
Treatment  2 1557.56  778.78  18.251 8.437e-06 *** #Fixed effect
Residuals 28 1194.78   42.67
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1



I hope that this is of help.

John

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[R] FW: Re: Doubt about nested aov output

2005-09-07 Thread John Wilkinson \(pipex\)
Ronaldo,

Further to my previous posting  on your Glycogen nested aov model.

Having read Douglas Bates' response and  Reflected on his lmer analysis
output of your aov nested model example as given.The Glycogen treatment has
to be a Fixed Effect.If a 'treatment' isn't a Fixed Effect what is ? If
Douglas Bates' lmer model is modified to treat Glycogen Treatment as a
purely Fixed Effect,with Rat and the interaction Rat:Liver as random effects
then--

 model.lmer-lmer(Glycogen~Treatment+(1|Rat)+(1|Rat:Liver))
 summary(model.lmer)
Linear mixed-effects model fit by REML
Formula: Glycogen ~ Treatment + (1 | Rat) + (1 | Rat:Liver)
 AIC  BIClogLik MLdeviance REMLdeviance
 239.095 248.5961 -113.5475   238.5439  227.095
Random effects:
 GroupsNameVariance   Std.Dev.
 Rat:Liver (Intercept) 2.1238e-08 0.00014573
 Rat   (Intercept) 2.0609e+01 4.53976242
 Residual  4.2476e+01 6.51733769
# of obs: 36, groups: Rat:Liver, 6; Rat, 2

Fixed effects:
Estimate Std. Error DF t value  Pr(|t|)
(Intercept) 140.5000 3.7208 33 37.7607  2.2e-16 ***
Treatment2   10.5000 2.6607 33  3.9463 0.0003917 ***
Treatment3   -5. 2.6607 33 -2.0045 0.0532798 .
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Correlation of Fixed Effects:
   (Intr) Trtmn2
Treatment2 -0.358
Treatment3 -0.358  0.500

 anova(model.lmer)
Analysis of Variance Table
  Df  Sum Sq Mean Sq   Denom F valuePr(F)
Treatment  2 1557.56  778.78   33.00  18.335 4.419e-06 ***
 
which agrees with the aov model below.

  model - aov(Glycogen~Treatment+Error(Rat/Liver))
 summary(model)


John

-Original Message-
From: John Wilkinson (pipex) [mailto:[EMAIL PROTECTED]
Sent: 07 September 2005 12:04 PM
To: Ronaldo Reis-Jr.
Cc: r-help
Subject: Re: [R] Doubt about nested aov output


Ronaldo ,

It looks as though you have specified your model incorrectly.

In the Rats example ,the Treatment is the only fixed effect,Rat and Liver
are random effects

In aov testing for sig of 'Means' of Random Effects is pointless and that is
why 'p' values are not given.Further more the interaction between a Random
Effect and a Fixed Effect is also a Random Effect. The 'aov' with error
structure terms output reflects this by only giving 'p' values to
Fixed Effects and their interactions

  model - aov(Glycogen~Treatment+Error(Rat/Liver))
 summary(model)

Error: Rat
  Df Sum Sq Mean Sq F value Pr(F) #Rat is random effect
Residuals  1 413.44  413.44

Error: Rat:Liver  #Rat:Liver is Random 
effect
  Df  Sum Sq Mean Sq F value Pr(F)
Residuals  4 164.444  41.111

Error: Within
  Df  Sum Sq Mean Sq F valuePr(F)
Treatment  2 1557.56  778.78  18.251 8.437e-06 *** #Fixed effect
Residuals 28 1194.78   42.67
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1



I hope that this is of help.

John

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[R] stepAIC invalid scope argument

2005-08-16 Thread John Wilkinson \(pipex\)

Adai,

The following works.Perhaps you should define your 'upper' and 'lower'
in the list as aov's, as you have done with your lo,hi and mid.

John

  stepAIC( mid, scope=list(upper = mid , lower = lo) )
Start:  AIC= -594.66 
 y ~ x2 + x3 

   Df Sum of Sq RSS AIC
- x21  0.11  548.56 -596.45
- x31  0.95  549.40 -594.93
none   548.45 -594.66

Step:  AIC= -596.45 
 y ~ x3 

Adaikalavan Ramasamy wrote ---

I am trying to replicate the first example from stepAIC from the MASS
package with my own dataset but am running into error. If someone can
point where I have gone wrong, I would appreciate it very much. 

Here is an example :

 set.seed(1)
 df   - data.frame( x1=rnorm(1000), x2=rnorm(1000), x3=rnorm(1000) )
 df$y - 0.5*df$x1 + rnorm(1000, mean=8, sd=0.5)
 # pairs(df); head(df)

 lo  - aov( y ~ 1, data=df )
 hi  - aov( y ~ .^2, data=df )
 mid - aov( y ~ x2 + x3, data=df )

Running any of the following commands

 stepAIC( mid, scope=list(upper = ~x1 + x2 + x3 , lower = ~1) )
 stepAIC( mid, scope=list(upper = hi , lower = lo) )
 addterm( mid, ~ x1 + x2 + x3 )
 addterm( lo, hi )

gives the same error message : 
  Error in eval(expr, envir, enclos) : invalid second argumen

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Re: [R] Question about 'text'

2005-07-24 Thread John Wilkinson
Dan,

Another tweak  !

If you want the 'legend' to look pretty you can resize it by adding,say,

'cex=0.6' into the legend code; try---

legend(topleft, #inset=-1,
  legend = do.call(expression, L),
  bg='white',
  ncol = 2,
  pch=c('','','',':',':',':'),
  x.intersp = 0.4,
  title=Yay! Thank You!,
cex=0.6
  )


John

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Re: [R] plot question

2005-07-03 Thread John Wilkinson \(pipex\)

a.d.

I refer you to ?title and its given examples.

try this --

plot(rnorm(10),rnorm(10),xlab= ,ylab= )
title(xlab=year,
ylab=expression(paste('M x'*10^{3},)),font=2)

note that 'title()' will alos accept a list for x and y labs,
for additional parameters,e.g., 'col' and 'cex'


John

a.d wrote---

dear list:

in the following plot:

plot(rnorm(10),rnorm(10),xlab=year,ylab=expression
(paste('M x'*10^{3},)),font.lab=2)

font.lab=2, but xlab and ylab are different. I want 
both labels in the same way. help?

a.d.

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Re: [R] plot question

2005-07-03 Thread John Wilkinson \(pipex\)

Gabor,

I thought that I had worked around the 'expression' format problem,
but if the x-y labels are to be bold, then using,say, cex.lab=1.25in the
title(), appears to simulate 'bold' font very well, both for the ylab maths
expression and xlab text.

Your solution is the rigorous one!

John

for example --

plot(rnorm(10),rnorm(10),xlab= ,ylab= )
title(xlab=year,
ylab=expression(paste(M x*10^{3})),font.lab=1,col.lab=4,
cex.lab=1.25)


Gabor Grothendieck wrote ---

Trying characters and expressions variously it seems that font.lab applies
to character strings but not to expressions so if you want to use an
expression
just use bold (or whatever) explicitly on the expression.  One gotcha is
that
bold will not work as one might have expected on numbers so they must
be represented as character strings -- which is why we have used 3 rather
than 3 below.

plot(rnorm(10),rnorm(10),xlab=quote(bold(year)),ylab=quote(bold(Mx10^3))
)

On 7/2/05, alex diaz [EMAIL PROTECTED] wrote:
 dear list:

 in the following plot:

 plot(rnorm(10),rnorm(10),xlab=year,ylab=expression
 (paste('M x'*10^{3},)),font.lab=2)

 font.lab=2, but xlab and ylab are different. I want
 both labels in the same way. help?

 a.d.


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[R] Re Components of variance

2005-06-26 Thread John Wilkinson \(pipex\)

John,

In addition to 'VarCorr(nlme) and VarCorr(Matrix)', you could also try
'varcomp' function in the 'ape' package.This requires an 'lme' class of
file, from the 'nlme package as input.It additionally gives the options to
scale the components by normalizing them (both cumulatively and in total).

I hope this helps,

John

John Sorkin Wrote-


Could someone identify a function that I might use to perform a
components of variance analysis? In addition to the variance
attributable to each factor, I would also like to obtain the SE of the
variances.
Thank you,
John

John Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
Baltimore VA Medical Center GRECC and
University of Maryland School of Medicine Claude Pepper OAIC

University of Maryland School of Medicine
Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524

410-605-7119
-- NOTE NEW EMAIL ADDRESS:
[EMAIL PROTECTED]

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Re: [R] extracting components of a list

2005-06-14 Thread John Wilkinson \(pipex\)
Dimitris,

wouldn't this be more precise ---

 sapply(jj,function(x) which(x$b[1]==4))

[[1]]
[1] 1

[[2]]
numeric(0)

[[3]]
[1] 1

 John

Dimitris wrote ---


maybe something like this:

jj - list(list(a = 1, b = 4:7), list(a = 5, b = 3:6), list(a = 10, b 
= 4:5))
###
jj[sapply(jj,  function(x) x$b[1] == 4)]


I hope it helps.

Best,
Dimitris


Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.ac.be/biostat/
 http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm



- Original Message - 
From: Robin Hankin [EMAIL PROTECTED]
To: r-help R-help@stat.math.ethz.ch
Sent: Monday, June 13, 2005 4:23 PM
Subject: [R] extracting components of a list


 Hi

 how do I extract those components of a list that satisfy a certain
 requirement?  If

 jj - list(list(a=1,b=4:7),list(a=5,b=3:6),list(a=10,b=4:5))


 I want just the components of jj that have b[1] ==4 which in this 
 case
 would be the first and
 third of jj, vizlist (jj[[1]],jj[[3]]).

 How to do this efficiently?

 My only idea was to loop through jj, and set unwanted components to
 NULL, but
 FAQ 7.1 warns against this.




 --
 Robin Hankin
 Uncertainty Analyst
 National Oceanography Centre, Southampton
 European Way, Southampton SO14 3ZH, UK
  tel  023-8059-7743


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[R] identify label format problem

2005-06-13 Thread John Wilkinson \(pipex\)
Hi ,

I am attempting to format the 'identify' function labels.
I can format the colour but the 'cex' parameter appears not to work
for me.

example--

 x-1:5
 y-1:5
 plot(x,y)
 identify(x,y,cex=0.5,col=2)
[1] 3

The label is coloured red but the 'cex=0.5' does not reduce 
the label size. Why not,, am I doing it wrong ?


 version
 _  
platform i386-pc-mingw32
arch i386   
os   mingw32
system   i386, mingw32  
status  
major2  
minor1.0
year 2005   
month04 
day  18 
language R 

Thanks for any help,

John

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[R] two line plot title with expression problem

2005-02-25 Thread John Wilkinson (pipex)
Dear R-users,

I am having a problem formatting a two line plot title with the first line
text and the second line an expression. I can’t get the second line
expression to line up with the first by starting at the LHS of the line.

A simple example illustrates the situation.

x-seq(-5,5,length=100)
f-function(x) x^2-x-1


For a one line title the following works fine—

plot(x,f(x),type=l)
title(expression(paste(Golden Section  ,fn:(phi^2-phi-1)),sep=))

but when attempting a two line title as follows--

plot(x,f(x),type=l)
title(expression(paste(Golden Section\n  ,fn:(phi^2-phi-1)),sep=))

the second line containing the expression for phi is indented,
to the right, starting immediately after the position of the end
letter of the first line.

If the second line were to be text, this would not be a problem.

How can I format the title so that the expression starts immediately under
the first line?

Thanks for help.


John.

[John Wilkinson : [EMAIL PROTECTED]

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[R] Re:how to compute a mode of a distribution

2004-08-26 Thread John Wilkinson
On 08/24/04 13:50, Paolo Tommasini wrote:

Hi my name is Paolo Tommasini does anyone know how to compute a mode
( most frequent element ) for a distribution ?

try

median(density(my.vector))


John

John Wilknson

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Re: [R] Re:how to compute a mode of a distribution

2004-08-26 Thread John Wilkinson
you are quite right  ,I forgot to insert $x,

I should have written

median(density(my.vector)$x)

that gives a median result but it is still  not the proper result.

density(my.vector)$y)

gives the probabilites y of each x value
The correst answer would be the value of x corresponding to

y=max(density(my.vector)$y)

see
summary(density(my.vector)

of course a

plot(density(my.vector))

would reveal the mode easily by inspection.

John





- Original Message - 
From: Kjetil Brinchmann Halvorsen [EMAIL PROTECTED]
To: John Wilkinson [EMAIL PROTECTED]
Cc: Paolo Tommasini [EMAIL PROTECTED]; [EMAIL PROTECTED]
Sent: Thursday, August 26, 2004 1:49 PM
Subject: Re: [R] Re:how to compute a mode of a distribution


 John Wilkinson wrote:

 On 08/24/04 13:50, Paolo Tommasini wrote:
 
 
 
 Hi my name is Paolo Tommasini does anyone know how to compute a mode
 ( most frequent element ) for a distribution ?
 
 
 
 try
 
 median(density(my.vector))
 
 
 
 That cannot be right. Try:

   test - rnorm(1000)
   d - density(test)
   median(d)
 Error in median(d) : need numeric data
   str(d)
 List of 7
  $ x: num [1:512] -3.64 -3.63 -3.62 -3.60 -3.59 ...
  $ y: num [1:512] 2.16e-05 2.60e-05 3.11e-05 3.71e-05 4.43e-05 ...
  $ bw   : num 0.221
  $ n: int 1000
  $ call : language density(x = test)
  $ data.name: chr test
  $ has.na   : logi FALSE
  - attr(*, class)= chr density
   i - which.max(d$y)
   d$x[i]
 [1] 0.05625893


 Kjetil halvorsen



 John
 
 John Wilknson
 
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[R] Unloading packages

2003-11-11 Thread John Wilkinson
In order to update the packages from Cran, it is first necessary
to unload all packages from the R Console.

Can anyone, please, inform me, how to unload all loaded packages with one
command?

Thanks for any help,

John Wilkinson

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