Displaying 20 results from an estimated 10000 matches similar to: ""non-sample" standard-deviation"
2009 Nov 09
4
prcomp - principal components in R
Hello, not understanding the output of prcomp, I reduce the number of
components and the output continues to show cumulative 100% of the
variance explained, which can't be the case dropping from 8 components
to 3.
How do i get the output in terms of the cumulative % of the total
variance, so when i go from total solution of 8 (8 variables in the data
set), to a reduced number of
2009 Jul 14
5
plotting confidence intervals
Hi R People:
If I have a fitted values from a model, how do I plot the
(1-alpha)100% confidence intervals along with the fitted values,
please?
Also, if the intervals are "shaded" gray, that would be nice too, please?
I check confint, but that doesn't seem to do what I want.
Thanks in advance,
Sincerely,
Erin
--
Erin Hodgess
Associate Professor
Department of Computer and
2009 Jul 09
9
Population pyramids
Hi, I hope somebody can help me with this issue: I am doing population pyramids using the barplot command, so in the left side I have male age structure and in the right side the female age structure. To plot the male age structure I put the data in negative numbers. Now, I want to change the sign in the bar plot in such way that I have no-sign numbers, both in left and right side of the graph. I
2008 Feb 26
3
OLS standard errors
Hi,
the standard errors of the coefficients in two regressions that I computed
by hand and using lm() differ by about 1%. Can somebody help me to identify
the source of this difference? The coefficient estimates are the same, but
the standard errors differ.
####Simulate data
happiness=0
income=0
gender=(rep(c(0,1,1,0),25))
for(i in 1:100){
happiness[i]=1000+i+rnorm(1,0,40)
2009 Oct 02
2
how to fill out the empty spots when using rbind or cbind?
I have uneven vectors I want to use cbind or rbind to combine them into a matrix. Is there a way to make it so that R would not return error msg saying they're uneven?
Thanks.
Edward Chen
Email: tkedch@msn.com
Cell Phone: 510-371-4717
[[alternative HTML version deleted]]
2009 Jul 24
4
CI wiskers
I have a matrix containing means and CIs (lower and upper in two columns, so
three columns for every data point) for several points. I have to build a
graph of these means accompained by the CIs (as wiskers). No problems with
making the graph of means, but I don't know how to introduce CIs.
Can anybody advise?
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2008 Jul 08
1
aggregate() function and na.rm = TRUE
All,
I've been using aggregate() to compute means and standard deviations at
time/treatment combinations for a longitudinal dataset, using na.rm = TRUE
for missing data.
This was working fine before, but now when I re-run some old code it isn't.
I've backtracked my steps and can't seem to find out why it was working
before but not now. In any event, below is a reproducible
2008 Sep 02
2
Help with nonlinear regressional
Dear All,
I am doing experiments in live plant tissue using a laser confocal
microscope. The method is called "fluorescence recovery after
photo-bleaching" (FRAP) and here follows a short summary:
1. Record/ measure fluorescence intensity in a defined, round region of
interest (ROI, in this case a small spot) to determine the initial intensity
value before the bleaching. This
2008 Feb 27
4
Error in cor.default(x1, x2) : missing observations in cov/cor
Hello,
I'm trying to do cor(x1,x2) and I get the following error:
Error in cor.default(x1, x2) : missing observations in cov/cor
A few things:
1. I've used cor() many times and have never encountered this error.
2. length(x1) = length(x2)
3. is.numeric(x1) = is.numeric(x2) = TRUE
4. which(is.na(x1)) = which(is.na(x2)) = integer(0) {the same goes for
is.nan()}
5. I also try
2009 Feb 19
4
problem with comparing a part of string with whole string
Hi all,
I got one problem with comparing strings like if any string is like
"*RIGHT, EPICARDIUM: FOCUS, GRAY-WHITE, SINGLE, APPROX 0.6 CM IN DIAMETER*."
and i have to compare "*GRAY-WHITE*" with the above string
or otherwise i have to compare " *TUMOR BENIGN*" this string
with
"*MEDULLRY TUMOR BENIGN,TYP PHEOCHROMOCYTOMA*"
i
2009 Jul 26
1
Assessing standard errors of polynomial contrasts
Hi, using polynomial contrasts for the ordered factors in an experiment
leads to much nicer covariance structure than using treatment contrasts. It
is easy to assess the mean effect for each of the experimental groups.
However, standard errors are provided only for the components of the
orthogonal contrasts. I wonder how to assess the standard errors not of the
components, but of the respective
2007 Sep 12
2
Nested anova with unbalanced design and corrected sample size for spatial autocorrelation
Hello all,
This may be a simple question to answer, but I'm a little bit stumped with
respect to the calculation of the F statistics in nested anovas with
unbalanced design in R.
In my case, I have 11 vegetation transects (with 1000 10cmx10cm squares),
where we estimated shrub cover. We have two different treatments: wildfire
(4 transects) and prescribed burning (7 transects) and we want to
2009 Dec 11
1
random effects in mixed model not that 'random'
Hi,
I have the following conceptual / interpretative question regarding
random effects:
A mixed effects model was fit on biological data, with observations
coming from different species. There is a clear overall effect of
certain predictors (entering the model as fixed effect), but as
different species react slightly differently, the predictor also enters
the model as random effect and with
2009 Sep 20
3
statistics
The myoglobin sequence, with reference number NM_005368 in Gen bank, has the
following
frequencies of DNA nucleotides:
A C G T
237 278 309 242
Do these data provide sufficient evidence, at the 1% level of significance,
that the DNA nucleotides
have an unequal distribution, that is the DNA nucleotides are not evenly
utilised?
Clearly state your hypothesis, test statistic and conclusion.
2010 Apr 08
2
Problem using elements in a vector
Hi
So my particular problem is this:
I have a row vector of length 5200 elements - specifically created by
x<-rbinom(5200,1,0.5)
y<-matrix(x,nrow=1,ncol=5200)
y
now, each element is either a 0 or a 1 - e.g. it could be
(0,1,1,1,1,0,0,0,1,1,1) e.t.c.
when the element is a 1, i need to multiply a number (say 1000) by 1.005,
and if it is 1 again, multiply it _again_ by 1.005.
so for
2009 Nov 11
3
how to use # in a rd doc in url address
I am writing a rd doc, and need to use "#" in a url adress. This would make:
\url{http://www.xxxx.org/myfolder/#myanchor}
Of course, I suppose this will not work because # is a special character
starting a comment line in the rd dialect. I did not found a similar
example in "Writing R exentions". I am not sure bout using \dQuote{a
quotation}), and use \sQuote and \dQuote
2008 Mar 31
2
Finding a mean value of a variable holding a dummy variable fixed
I have time-series data on approval ratings of British Prime Ministers. The
prime ministers dating from MacMillan onward till today are coded as dummy
variables and the approval ratings are entered for each month. I want to
know the mean value of the approval rating of each Prime Minister in the
dataset and the approval rating during his/her first month and last month as
PM. What R code should
2003 Aug 06
1
Standard error of standard deviation: bootstrap or theoretical results?
Dear R users,
This is more a statistical question rather than an R question. I'd
appreciate it if you can give me some suggestions.
I have a sample of a time series (sample size 500, fat tail in density). I
am trying to calculate the Standard error of standard deviation of a
sub-block-sample (sample size 250). I take 100 this kind of
sub-block-sample, randomly. For these 100 subsamples, I
2008 Oct 15
3
Standard deviation for rows
Hi everyone,
I have just started using R, and I have a simple question.
How can I get the Standard deviation for rows. basically I am looking for
something like "rowMeans()"
but for Standard deviation (I tried "rowSds()" didn't exist)
Thanks,
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2012 Aug 25
2
Standard deviation from MANOVA??
Hi,
I have problem getting the standard deviation from the manova output.
I have used the manova function: myfit <- manova(cbind(y1, y2) ~ x1
+ x2 + x3, data=mydata) .
I tried to get the predicted values and their standard deviation by using:
predict(myfit, type="response", se.fit=TRUE)
But the problem is that I don't get the standard deviation values, I only