Displaying 20 results from an estimated 70000 matches similar to: "calculate effect size from p-value?"
2011 Aug 05
1
Main-effect of categorical variables in meta-analysis (metafor)
Dear R-experts!
In a meta-analysis (metafor) I would like to assess the effect of two
categorical covariates (A & B) whereas they both have 4 levels.
Is my understanding correct that this would require to dummy-code (0,1) each
level of each covariate (A & B)?
However I am interested in the main-effects and the interaction of these two
covariates and the dummy-coding would only allow to
2011 Jul 18
1
Extract confidence intervals from rma object (metafor package)
Dear R-experts!
I am working on some meta-analysis using the metafor package. I would like
to extract values of the confidence intervals of the effect sizes of the
single studies from an rma object. Those values are printed out when
plotting a forest plot using the forest function on the rma object, however
I was not able to locate them.
Many thanks for your help!
Jokel
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2011 Jul 27
1
Converting F-value from ANOVA to cohen's d in meta-analysis (metafor-package)
Dear R-experts!
Running a meta-analysis (using the magnificent metafor-package), I use
cohen's d as a main outcome measure in a random-effects model.
For most of the samples cohen's d is derived form a comparison of two groups
(A & B). However some studies report results from an ANOVA (one-factor with
three levels: C,D,E) whereas two groups (C,D) correspond to one group in the
other
2013 Mar 03
2
Kolmogorov-Smirnov: calculate p value given as input the test statistic
Dear all,
I calculate the test statistic for the KS test outside R, and wish to use R
only to calculate the corresponding p-value.
Is there a way for doing this? (as far as I see, ks.test() requires raw
data as input). Alternatively, is there a way to provide the ks.test() the
two CDFs (two samples test) rather than the (x, y) data vectors?
Thanks in advance,
Rani
2009 Sep 04
0
Large p, small n. Impossible to calculate the p-value
Hello,
I have I problem and I hope someone can help me.
I have a data set with 66 variables and 30 values for each variable. I need
to calculate the Pearson correlation and the p-values among variables. I
have the ?large p, small n? problem so I used a shrinkage process to obtain
the r values. My problem is that I can?t calculate the p-values because the
degree of freedom of the t-student
2011 Jan 26
1
How to calculate p-value for Kolmogorov Smirnov test statistics?
Although I saw this issue being discussed many times before, I still
did not find the answer to:
why does R can not calculate p-values for data with ties (i.e. -
sample with two or more values the same)?
Can anyone elaborate some details about how does R calculate the p-
values for the Kolmogorov Smirnov test statistics?
I can understand the theoretical problem that continuous distributions
do
2011 Aug 17
1
How would you calculate this type of p-value using R?
Let's say you want to compare "one observation" with a sample, how would you
use R to get a p-value for that single observation itself?
To clarify what I'm asking: We know you use a one-sample t test to compare
an actual sample to a hypothetical value, and a Wilcoxon test if it's not
normally distributed, in R either "t.test( )" or "wilcox.test( )".
2010 Aug 25
1
Estimate average standard deviation of mean of two dependent groups
Dear R-experts!
I am currently running a meta-analysis with the help of the great metafor
package. However I have some difficulties setting up my raw data to enter it
to the meta-analysis models.
I have a group of subjects that have been measured in two continuous
variables (A & B). I have the information about the mean of the two
variables, the group size (n) and the standard deviations of
2012 Apr 25
1
calculate correlation effect size using contrast analysis for an omnibus Chi-square test statistic
I am looking for an R package with which one can calculate an effect size for a set of contrasts given an omnibus chi-square test statistic (more than 1 degree of freedom). Is there such a package? Presumably, it would implement the procedure (or something like it) described by Roznow and Rosenthal 1996 Psychological Methods 1: 331-340.
many thanks!
Steven Orzack
Fresh Pond Research Institute
2012 Jul 24
1
Annotate forest plot 'forest.rma()' for meta-analysis with metafor package
Dear R-experts,
The forest.rma() function from the metafor package creates nice forest
plots for presenting the results of a meta-analysis. These plots can be
annotated for e.g. giving names to the columns. E.g. as in the
documentation of the package:
data(dat.bcg)
### meta-analysis of the log relative risks using a random-effects model
res <- rma(ai=tpos, bi=tneg, ci=cpos, di=cneg,
2008 Sep 02
1
aov or lme effect size calculation
(A repost of this request with a bit more detail)
Hi, All. I'd like to calculate effect sizes for aov or lme and seem
to have a bit of a problem. partial-eta squared would be my first
choice, but I'm open to suggestions.
I have a completely within design with 2 conditions (condition and
palette).
Here is the aov version:
> fit.aov <- (aov(correct ~ cond * palette +
2008 Aug 30
0
calculating effect size for aov or lme
Hi, All. I'd like to calculate effect sizes for aov or lme and seem
to have a bit of problems. partial-eta squared would be my first
choice, but I'm open to suggestions.
Here is the aov version:
> fit.aov <- (aov(correct ~ cond * palette + Error(subject),
data=data))
> summary(fit.aov)
Error: subject
Df Sum Sq Mean Sq F value Pr(>F)
Residuals 15 0.17326
2004 Oct 18
1
meta.summaries and se's of effect sizes
Hi All,
I would like to use meta.summaries from package rmeta to do a meta-analysis.
I have available effect sizes as r's (which could be easily transformed to
effect sizes in terms of d's).
My problem is that I'm not sure what the se's of these r's should be ...
The r-values are themselves computed from F-tests and t-tests for various
studies.
Are there R-functions that
2010 Mar 26
4
How to calculate per_page value based on browser window size for will_paginate
def self.per_page
20
end
Any suggestion on how I can calculate this value base on the size of
the browser window?
Thanks
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2012 Jun 24
2
Power calculation using pwr.t.test()
Dear R experts,
I have conducted a power calculation in order to estimate the number of
subjects needed to detect an effect size of d=0.28 (cohen's d) for a
difference between two independent groups (alpha level should be 0.05 and
the effect should be detected with 80% probability).
The results from the code below indicates that I would need n=400 subjects
(200 in each group). This is seems
2011 Aug 19
3
Calculating p-value for 1-tailed test in a linear model
Hello,
I'm having trouble figuring out how to calculate a p-value for a 1-tailed
test of beta_1 in a linear model fit using command lm. My model has only 1
continuous, predictor variable. I want to test the null hypothesis beta_1
is >= 0. I can calculate the p-value for a 2-tailed test using the code
"2*pt(-abs(t-value), df=degrees.freedom)", where t-value and degrees.freedom
2008 Feb 03
1
Effect size of comparison of two levels of a factor in multiple linear regression
Dear R users,
I have a linear model of the kind
outcome ~ treatment + covariate
where 'treatment' is a factor with three levels ("0", "1", and "2"),
and the covariate is continuous. Treatments "1" and "2" both have
regression coefficients significantly different from 0 when using
treatment contrasts with treatment "0" as the
2010 Jul 22
2
p-VALUE calculation
Here is my dataframe with 1000 rows:
employee_id weigth p-value
100 150
101 200
102 300
103 180
.....
My question:
how can I calculate the p-value in R for each employee? the
distribution of the weigth will be established from the above 1000 samples.
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2003 Sep 16
1
calculation of the p value in ks.test()
Hi,
I'm working with the ks.test() function and I have also implemented
the test using Conover as the reference. My D value matches that
produced by R. However to calculate the p value I am using the code
described in Numerical Recipes in C++ (2nd Ed.) pg 631.
The p value produced by the NRC code is generally larger than that
produced by R by a factor of 10. Currently I am not in a position
2005 May 19
1
Calculation of Durbin-Watson p-value
Sir,
I am unable to get the source code for Durbin-Watson test, as I want to calculate the p-value for Durbin Watson statistic using interpolation method. I sent this mail to r-help, but it was rejected, please suggest me some way. I will be highly greatful to you.
Thanks in advance
Ramesh
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