19 November 2012

The Sound of Music meets Linear Programming

“Let’s start at the very beginning – a very good place to start. When you read you begin with A, B,C!” When you do statistics you begin with…probability? the mean? graphs? Begin at the end But really, is the beginning a very good place to start? Sometimes, we need to begin at the end. And sometimes we need to go back before the beginning. Always we need to think about where to begin, because it is seldom obvious, and copying what other teachers and textbooks have done is often a bad idea. Linear programming Take Linear Programming, the flagship technique […]
26 June 2012

All models are wrong

In my title I quote George Box, who wrote,  “Essentially, all models are wrong, but some are useful“. I wish economists would remember this more often. Statistics and Operations Research (and many other sciences) are based on the concept of a mathematical model. Aspects of a “real world” problem are quantified, analysed, explored, experimented with, sometimes even optimised, and the results are linked back to the original problem. This idea of a model is one we have tried to teach our students. It is a surprisingly difficult idea, and one that needs frequent revisiting. The following diagram is more complex […]
30 April 2012

Embrace Change

I love graduations. At the University of Canterbury the academic staff act as marshals, helping the graduands to be in the right place at the right time in the right order wearing the right clothes and doing the right things. I have acted as a marshal for some years and love helping people to have a good experience. I love graduations because of the accomplishment they represent, and the efforts the student, the parents and the staff have made for these young people to complete their qualifications. This graduation was pretty special, as it was the class that had to […]
10 April 2012

Statistics Textbooks suck out all the fun.

In 1987 George Cobb published a paper evaluating statistics textbooks. I am very grateful for it, as it alerted me to the problems with textbooks, and introduced me to the man himself, whose work I greatly admire. Cobb explains that statistics is an inherently interesting and practical subject, but that many textbooks seem to have missed that, or concealed it from the students. The discipline of statistics is inherently fascinating, applied and important. So why do so many textbooks make it seem mechanistic and abstract? I have been examining textbooks, and wonder if the writers even like their subject matter, […]
8 March 2012

You’re teaching it wrong!

“Every year I teach them this and every year they get it wrong!”. This is a phrase I’ve heard from colleagues and from my own mouth. Then it dawned on me – if the students keep getting it wrong, maybe I’m teaching it wrong! Example of Linear regression analysis Here’s an example. In linear regression I found that students often had trouble interpreting the slope. They would get it the wrong way around, or just not get it. Every year it was the same and I repeatedly groaned at incorrect interpretations in their work. Then it struck me that maybe […]
13 January 2012
Titles Tell All

The Importance of Titles

My colleague has an obsession about titles – and it is starting to rub off on me. Any time our graduate students present their work, the first thing that grabs her (and now my) attention is the title – the opening slide on the Powerpoint presentation. She declares that clarity of title indicates clarity of thought. It tells us whether they have mastered what they are talking about themselves. A woolly title indicates woolly thinking. As a result of her indoctrination I have included as part of a regression write-up, that students are required to provide a suitable title. They […]
27 December 2011

Templates for statistical reports – spoon-feeding?

Here is the poll for today. Indicate what you think, then read what I think. Reporting the outputs of statistical analysis is tricky. It is not easy to be both correct and readable. There are so many nuances that can make a seemingly correct statement incorrect. For example when reporting the R-sq value from a regression analysis, I have seen it written that “temperature explains 63% of sales.” This is almost correct, but should read “temperature explains 63% of the variation in sales.” There is a subtle but important difference (which can be the subject of another post!) For many […]