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May 18, 2018

Last week I gave a course about design of experiments at a major life science research institute. The audience was mainly young PhD students. There were hardly any post-docs or research leaders. I assume because post-docs and research leaders think they don’t need training in design of experiments anymore. Anyhow. I just want to give a picture of the audience to indicate that they are not at the top of the food chain. They need to struggle for a piece of a bench or a growth chamber. They get the poor corner of the greenhouse that nobody else wants to use. They have limited resources and are under time pressure. Unfortunately, they also seem t...

May 10, 2018

The difference test starts from a hypothesis that claims the absence of a difference and by rejecting it, you make inferences about the existence of the difference. But what to do if you actually would like to prove the absence of a difference or equivalence? Can we use the same procedures? No, we cannot...

The requirement of equivalence is not that uncommon. For instance a new wheat variety has a superior baking quality, but it is lower yielding than a reference wheat variety. By breeding efforts the yields of the new variety are improved. At a certain point, we compare two varieties in the hope they are equivalent in yield. Inversely, a high...

April 16, 2018

An experiment is carried out to learn something. Usually that experiment is not the only source of evidence. There may have been earlier experiments with similar goals. There is usually some prior knowledge about what is tested. The experiment itself provides additional information but that information is never standing on its own. In the context of biological research, the experiment is usually set up to learn about a certain hypothesis or to estimate a certain parameter.

In the case of a hypothesis that needs testing, the outcome of the analysis of the data will contain some statement about how much evidence there is for or against that hypo...

March 2, 2018

Any researcher active in the area of biology, agronomy, and other life sciences has some knowledge on experimental design and statistical analysis from their days in university and through their experience in their field of work. Statistical software is readily available which also allows them to apply this knowledge. The statistical issues seem surmountable and secondary to other issues they are confronted with. Pondering about statistics or seeking help from statisticians is therefor not often the highest priority.

This is a pity. As a practicing statistician I encountered many situations where research was poorly designed or wrong (or not e...

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Joris De Wolf

Hoogbos 15 A

9660 Brakel - Belgium

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