Articles by grumble10

Importing 100 years of climate change into R

May 5, 2014 | grumble10

This is a flashback post, I was working on species distribution shifts over the last 40 years last summer and recently Rémi Genevest contacted me asking me how I managed to import the CRU TS 1.2 dataset into R. As always a more readable version of the code can be found ... [Read more...]

Checking (G)LM model assumptions in R

April 16, 2014 | grumble10

(Generalized) Linear models make some strong assumptions concerning the data structure: Independance of each data points Correct distribution of the residuals Correct specification of the variance structure Linear relationship between the response and the linear predictor For simple lm 2-4) means that the residuals should be normally distributed, the variance ... [Read more...]

Interpreting interaction coefficient in R (Part1 lm)

April 8, 2014 | grumble10

Interaction are the funny interesting part of ecology, the most fun during data analysis is when you try to understand and to derive explanations from the estimated coefficients of your model. However you do need to know what is behind these estimate, there is a mathematical foundation between them that ... [Read more...]

Generalized Linear Mixed Models in Ecology and in R

March 12, 2014 | grumble10

I had a nice workshop two weeks ago in Tübingen (south-germany) concerning Generalized Linear Mixed Models (GLMM) in R. The course was given by two ecologist: Dr. Pius and Fränzi Korner-Nievergelt  that spend now half of their time doing statistical consulting ( ... [Read more...]

Computing R square for Generalized Linear Mixed Models in R

March 2, 2014 | grumble10

R square is a widely used measure of model fitness, in General Linear Models (GLM) it can be interpreted as the percent of variance in the response variable explained by the model. This measure is unitless which makes it useful to compare model between studies in meta-analysis analysis. Generalized Linear ... [Read more...]

Adding color to R plot: a function

February 24, 2014 | grumble10

A friend of mine told me that she was spending her day colouring R plot because she never understood how to put color in them. This triggered a nerdy reaction in me that I had to put in a basic function. This was actually a funny exercise for two reasons: ... [Read more...]

Simulating dice throws in R

December 20, 2013 | grumble10

I am currently following a course on probability theory in coursera ( and I’ve seen some graphs concerning the outcome of some dice throws. Being an R-nerd I wrote a little function to do this in R. This is nothing fancy just I find ... [Read more...]

Non-linear regression in R

August 25, 2013 | grumble10

Here is the link to the article: There you will discover how to simulate and fit: power function, Michaelis-Menten equation and sigmoid curves in R, the fit is done by least-square using the ‘nls’ function.Filed under: R and Stat Tagged: NLS, R [Read more...]

Generalized Linear Modelling in R (part 1)

July 20, 2013 | grumble10

In classical linear modelling we are assuming that the response variable (Y) is normally distributed, however for certain type of data like count data or presence/absence data this is not the case. There is in statistic an ensemble of technique called Generalized Linear Modelling (GLM in short) where the ... [Read more...]
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