278 search results for "anova"

R 2.15.2 now available

October 26, 2012
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As promised, the source distribution for R 2.15.2 is now available for download from the master CRAN repository. (Binary distributions for Windows, MacOS and Linux will be available from the CRAN mirror network in the coming days.) This latest point-update — codenamed "Trick or Treat" — improves the performance of the R engine and adds a few minor but...

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R for Ecologists: Permutation Analysis – t-tests

October 24, 2012
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R for Ecologists: Permutation Analysis – t-tests

You’ve carefully designed your experiment, you’ve meticulously collected your data, and you have a hypothesis to test. Unfortunately, your data is typical of ecology data: small sample sizes, messy, and non-normal. Your ideal test, the t-test, won’t work because of the … Continue reading →

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Recoding Variables in R: Pedagogic Considerations

October 20, 2012
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I was creating a dataset this last week in which I had to partition the observed responses to show how the ANOVA model partitions the variability. I had the observed Y (in this case prices for 113 bottles of wine), … Continue reading →

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Power and Sample Size Analysis: Z test

October 17, 2012
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Power and Sample Size Analysis: Z test

This article provide a brief background about power and sample size analysis. Then, power and sample size analysis is computed for the Z test. Continue reading →

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Color Palettes in HCL Space

October 12, 2012
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Color Palettes in HCL Space

This is a quick follow-up to my previous post about Color Palettes in RGB Space. Achim Zeileis had commented that, perhaps, it would be more informative to evaluate the color palettes in HCL (polar LUV) space, as that spectrum more accurately describes how humans perceive color. Perhaps more clear trends would emerge in HCL space,

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Product revenue prediction with R – part 2

October 8, 2012
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Product revenue prediction with R – part 2

After development of predictive model for transactional product revenue -(Product revenue prediction with R – part 1), we can further improvise the model prediction by modifications in the model. In this post, we will see what are the steps required for model improvement. With the help of a set of model summary parameters, the data

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Two ways that correlation and stepwise regression can give different results

October 8, 2012
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In general, a correlation test is used to test the association between two variables (y and z). However, if there is a third variable (x) that might be related to z or y, it makes...

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Parse pdf files with R (on a Mac)

October 4, 2012
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Inspired by this blog post from theBioBucket, I created a script to parse all pdf files in a directory. Due to its reliance on the Terminal, it’s Mac specific, but modifications for other systems shouldn’t be too hard (as a start for Windows, see BioBucket’s script). First, you have to install the command line tool

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R 2.15.2 scheduled for October 26

October 2, 2012
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The next minor update to R — version 2.15.2 "Trick or Treat" — will be released on October 26, R-core member Peter Dalgaard announced today. You can find the planned updates in the current NEWS file (scroll down to the section 'CHANGES IN R VERSION 2.15.1 patched'; the changes at the top of the file are planned for the...

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Football, an ordinal model

September 30, 2012
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Football, an ordinal model

On September 19th, flo2speak remarked under a post that his/her experience is that ordinal models had better performance. That seems reason enough to try, so there we are. In examining this type of model it is found that more complex models can be...

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