2 February 2012

Teaching Operations Research with food

What I like about Operations Research is its applied nature. It is mathematical and useful. We need to make sure that our students recognize that. As students have often had little experience in the world of business and manufacturing, it can be helpful to use examples based around food. Food is a universal topic. We all need food and most of us enjoy it and probably eat too much. For this reason food is a useful context to use in teaching. Linear programming diet problems The linear programming diet problem is an obvious starting place. For decades linear programs have […]
26 January 2012

Sampling Error Isn't

I hope you committed to a response in the box before reading this post. This is an important topic. Recently I read an amusing blog regarding poor sampling technique. The tweet that led to the link called it “a humorous look at sample error”. I’m hoping the person who tweeted meant bad sampling, because the problem is, the story was not about sampling error. And that is because sampling error isn’t. Isn’t what? It isn’t error. It doesn’t occur by mistake. It is not caused by bad procedures. There is nothing practical you can do when sampling to avoid sampling […]
20 January 2012

Textbooks and horseless carriages

Why do my students like me and the bookreps don’t? Because I do not require a textbook for either of my large entry level courses in Statistics and Operations Research. I have found that so few students use any prescribed text, that it is pointless prescribing one. I have found other ways to engage students and help them to learn the skills, attitudes and content that I believe are necessary. The other problem was that I never found a text that aimed to develop the same skills, attitudes and content that I wanted them to. Too many of them seemed […]
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 […]
6 January 2012
Five students

Should students calculate?

At an NCTM conference session on teaching statistics I suggested that there was no point in teaching how to calculate a standard deviation. It caused a somewhat heated response, mostly in opposition, but it did get us thinking. Similarly I have suggested that using the graphical method of Linear Programming is not helpful for most students, with similarly mixed response. The paper was rejected by reviewers. Each of those issues can have a post all of their own. What I want to discuss here is when calculation is useful, and when it isn’t. Type of student and purpose of the […]
3 January 2012

The meaning of the mean

Here is an exercise you might like to try on a class or individual, when introducing the mean. I have found it interesting and enlightening for all parties, especially those who think they know everything. Dr Nic: Tell me what a mean is, as if explaining it to someone who doesn’t know about statistics. Student: It’s an average. Dr Nic: Correct, however you haven’t really increased my understanding with that description. Student: It is what you get when you add all the numbers together and divide by the number of numbers. Dr Nic: That is a correct description of how to calculate a mean. Still […]
28 December 2011

Re Solutions

In this time of New Year resolutions I will post re solutions. ;)* In mathematics the solution is the answer. Examples: x=42. Theta is 57 degrees. The price has increased by 15%. In statistics a solution provides something we can be reasonably sure of. Examples: We are 95% confident that the price of a house increases by between $5,000 and $7,000 for each extra bathroom, all other things being equal. The margin of error is 3 percent. There is evidence that more men prefer milk chocolate than dark chocolate. What is called a solution in operations research could be called an […]
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 […]
21 December 2011
Understanding
Mathematical understanding is not the only kind of understanding. Cobb and Moore (1997)
20 December 2011

Statistics for all

Let’s start with a question. Please answer it now before you read any further! Statistics, like Operations Research, is a mathematical science. However people can be intelligent consumers of statistical analysis without having to use mathematics. The statement in the box above is false. Often statistics is taught by mathematics teachers, who understand the mathematical aspects of statistics, but may never have dirtied their hands with real data. They teach the mechanics of calculating the values of standard deviations and confidence intervals, intending that this will lead to understanding. Unfortunately many of their pupils do not gain understanding from the application […]