4 September 2014

Sampling error and non-sampling error

The subject of statistics is rife with misleading terms. I have written about this before in such posts as Teaching Statistical Language and It is so random. But the terms sampling error and non-sampling error win the Dr Nic prize for counter-intuitivity and confusion generation. Confusion abounds To start with, the word error implies that a mistake has been made, so the term sampling error makes it sound as if we made a mistake while sampling. Well this is wrong. And the term non-sampling error (why is this even a term?) sounds as if it is the error we make from […]
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. […]
16 September 2013

How to learn statistics (Part 2)

Some more help (preaching?) for students of statistics Last week I outlined the first five principles to help people to learn and study statistics. They focussed on how you need to practise in order to be good at statistics and you should not wait until you understand it completely before you start applying. I sometimes call this suspending disbelief. Next I talked about the importance of context in a statistical investigation, which is one of the ways that statistics is different from pure mathematics. And finally I stressed the importance of technology as a tool, not only for doing the […]
13 May 2013

Teaching statistical report-writing

Teaching how to write statistical reports It is difficult to write statistical reports and it is difficult to teach how to write statistical reports. When statistics is taught in the traditional way, with emphasis on the underlying mathematics the process of statistics is truncated at both ends. When we concentrate on the sterile analysis, the messy “writing stuff” is avoided. Students do not devise their own investigative questions, and they do not write up the results. Here’s the thing though – in reality, the analysis step of a statistical investigation is a very small part of the whole, and performed […]
29 April 2013

The median outclasses the mean

The median suffers from poor marketing. All my time at school the “average” was always calculated as the arithmetic mean, by adding up all the scores and then dividing by the number of scores. When we were taught about the median, it seemed like an inferior version of the mean. It was the thing you worked out when you weren’t smart enough to add and divide. It was used for house prices, and that was about it. Of course the mean was the superior product! Why wouldn’t you use the mean? I’ve been preparing resources for teaching the fabulous new […]
4 March 2013

Shibboleth, Mixolydian, Heteroscedasticity – and Kipling

All areas of human endeavour have specific language. Cricket commentators, art critics and wines buff make this very obvious. Mixolydian My son, who is blind, autistic and plays the piano like an angel, is studying Jazz, and I’m helping him. You can see him on his YouTube channel . There is a specific language around Jazz, and I’m not talking about ‘scat’. (Hmm just realised the other meaning for that word!) In the Jazz course they use words like Mixolydian, Chromatisism, Quartal Harmony…  I nod and smile. This language expresses ideas clearly and uniquely and is outside my comprehension. (Mixolydian is […]
27 March 2012

Teaching statistical language

I received a phone call from the company that leases us our equipment. I got quite excited when the salesman told me they would waive the purchase price of a new iPad. Then I decided it was time to clarify things. “Ok,” I said, “You are using the term ‘purchase price’. To me that means the amount you pay for something when you buy it. You are telling me that if I get a new iPad on the same lease as the old iPad you will waive the purchase price. This sounds great to me, but I can’t imagine I’ve […]