25 June 2014

It is so random! Or is it? The meaning of randomness

The concept of “random” is a tough one. First there is the problem of lexical ambiguity. There are colloquial meanings for random that don’t totally tie in with the technical or domain-specific meanings for random. Then there is the fact that people can’t actually be random. Then there is the problem of equal chance vs displaying a long-term distribution. And there is the problem that there are several conflicting ideas associated with the word “random”. In this post I will look at these issues, and ask some questions about how we can better teach students about randomness and random sampling. […]
20 January 2014

The Myth of Random Sampling

I feel a slight quiver of trepidation as I begin this post – a little like the boy who pointed out that the emperor has no clothes. Random sampling is a myth. Practical researchers know this and deal with it. Theoretical statisticians live in a theoretical world where random sampling is possible and ubiquitous – which is just as well really. But teachers of statistics live in a strange half-real-half-theoretical world, where no one likes to point out that real-life samples are seldom random. The problem in general In order for most inferential statistical conclusions to be valid, the sample […]