Articles by R on Fixing the bridge between biologists and statisticians

Dealing with correlation in designed field experiments: part II

February 9, 2025 | R on Fixing the bridge between biologists and statisticians

With field experiments, studying the correlation between the observed traits may not be an easy task. For example, we can consider a genotype experiment, laid out in randomised complete blocks, with 27 wheat genotypes and three replicates, where sev... [Read more...]

A trip from variance-covariance to correlation and back

January 23, 2025 | R on Fixing the bridge between biologists and statisticians

The variance-covariance and the correlation matrices are two entities that describe the association between the columns of a two-way data matrix. They are very much used, e.g., in agriculture, biology and ecology and they can be easily calculated wi...

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How do we combine errors? The linear case

November 21, 2024 | R on Fixing the bridge between biologists and statisticians

In our research work, we usually fit models to experimental data. Our aim is to estimate some biologically relevant parameters, together with their standard errors. Very often, these parameters are interesting in themselves, as they represent means,... [Read more...]

How do we combine errors, in biology? The delta method

November 21, 2024 | R on Fixing the bridge between biologists and statisticians

In a recent post I have shown that we can build linear combinations of model parameters (see here ). For example, if we have two parameter estimates, say Q and W, with standard errors respectively equal to \(\sigma_Q\) and \(\sigma_W\), we can build...

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Plotting weather data with ggplot()

May 23, 2024 | R on Fixing the bridge between biologists and statisticians

Very often, we agronomists have to deal with weather data, e.g., to evaluate and explain the behaviour of genotypes in different environments. We are very much used to representing temperature and rainfall data in one single graph with two y-axis, w...

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Here is why I don’t care about the Levene’s test

March 14, 2024 | R on Fixing the bridge between biologists and statisticians

During my stat courses, I never give my students any information about the Levene’s test (Levene and Howard, 1960), or other similar tests for homoscedasticity, unless I am specifically prompted to do so. It is not that I intend to underrate the tre...

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Articles by R on Fixing the bridge between biologists and statisticians

Dealing with correlation in designed field experiments: part II

A trip from variance-covariance to correlation and back

How do we combine errors? The linear case

How do we combine errors, in biology? The delta method

Plotting weather data with ggplot()

Here is why I don’t care about the Levene’s test