336 search results for "Anova"

Evaluating Logistic Regression Models

August 17, 2015
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Evaluating Logistic Regression Models

Logistic regression is a technique that is well suited for examining the relationship between a categorical response variable and one or more categorical or continuous predictor variables. The model is generally presented in the following format, where β refers to the parameters and x represents the independent variables. log(odds)=β0+β1∗x1+...+βn∗xn The log(odds), or log-odds ratio, is defined

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Count data: To Log or Not To Log

July 22, 2015
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Count data: To Log or Not To Log

Count data are widely collected in ecology, for example when one count the number of birds or the number of flowers. These data follow naturally a Poisson or negative binomial distribution and are therefore sometime tricky to fit with standard LMs. A traditional approach has been to log-transform such data and then fit LMs to

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Count data: To Log or Not To Log

July 22, 2015
By
Count data: To Log or Not To Log

Count data are widely collected in ecology, for example when one count the number of birds or the number of flowers. These data follow naturally a Poisson or negative binomial distribution and are therefore sometime tricky to fit with standard LMs. A traditional approach has been to log-transform such data and then fit LMs to

Read more »

Connecting R to Everything with IFTTT

June 18, 2015
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Connecting R to Everything with IFTTT

IFTTT ("if this then that") is one of my favorite tools. I use it to keep and share articles, turn on my home's lights at sundown, alert me when certain keywords are mentioned on Twitter/Reddit/etc., and many other things. Recently, the great people at IFTTT announced the Maker Channel, which allows recipes to make and receive web requests. This...

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Connecting R to Everything with IFTTT

June 18, 2015
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Connecting R to Everything with IFTTT

IFTTT (“if this then that”) is one of my favorite tools. I use it to keep and share articles, turn on my home’s lights at sundown, alert me when certain keywords are mentioned on Twitter/Reddit/etc., and many other things. Recently, the great people at IFTTT announced the Maker Channel, which allows recipes to make and receive...

Read more »

Connecting R to Everything with IFTTT

June 18, 2015
By
Connecting R to Everything with IFTTT

IFTTT (“if this then that”) is one of my favorite tools. I use it to keep and share articles, turn on my home’s lights at sundown, alert me when certain keywords are mentioned on Twitter/Reddit/etc., and many other things. Recently, the great people at IFTTT announced the Maker Channel, which allows recipes to make and receive...

Read more »

advanced.procD.lm for pairwise tests and model comparisons

June 9, 2015
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In geomorph 2.1.5, we decided to deprecate the functions, pairwiseD.test and pairwise.slope.test.   Our reason for this was two-fold.  First, recent updates by CRAN rendered these functions unstable.  These functions depended on the mode...

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Paper Helicopter Experiment, part III

May 31, 2015
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Paper Helicopter Experiment, part III

As final part of my paper helicopter experiment analysis (part I, part II) I do a reanalysis for one more data set. In 2002 Erik Erhardt and Hantao Mai did an extensive experiment, see The Search for the Optimal Paper Helicopter. They did a number of s...

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An R Enthusiast Goes Pythonic!

May 28, 2015
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An R Enthusiast Goes Pythonic!

I’ve spent so many years using and broadcasting my love for R and using Python quite minimally. Having read recently about machine learning in Python, I decided to take on a fun little ML project using Python from start to … Continue reading →

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Simulation-based power analysis using proportional odds logistic regression

May 22, 2015
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Simulation-based power analysis using proportional odds logistic regression

Consider planning a clinicial trial where patients are randomized in permuted blocks of size four to either a 'control' or 'treatment' group. The outcome is measured on an 11-point ordinal scale (e.g., the numerical rating scale for pain). It may be reasonable to evaluate the results of this trial using a proportional odds cumulative logit

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