# linear programming

16 December 2013

## Deterministic and Probabilistic models and thinking

The way we understand and make sense of variation in the world affects decisions we make. Part of understanding variation is understanding the difference between deterministic and probabilistic (stochastic) models. The NZ curriculum specifies the following learning outcome: “Selects and uses appropriate methods to investigate probability situations including experiments, simulations, and theoretical probability, distinguishing between deterministic and probabilistic models.” This is at level 8 of the curriculum, the highest level of secondary schooling. Deterministic and probabilistic models are not familiar to all teachers of mathematics and statistics, so I’m writing about it today. Model The term, model, is itself challenging. […]
17 December 2012

## Organising the toolbox in statistics and operations research

Don’t bury students in tools      In our statistics courses and textbooks there is a tendency to hand our students tool after tool, wanting to teach them all they need to know. However students can feel buried under these tools and unable to decide which to use for which task. This is also true in beginning Operations Research or Management Science courses. To the instructors, it is obvious whether to use the test for paired or independent samples or whether to use multicriteria decision making or a decision tree.  But it is just another source of confusion for the […]
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 […]
15 October 2012

## Optimal instruction in Statistics and Operations Research

Optimise everything! I had a colleague who believed that everything could and should be optimised. He had a diet Linear Program which he used to plan his meals to provide optimal nutrition. Unfortunately the Linear Program didn’t seem to have a constraint to ensure the food was palatable, and he would eat combinations like sardines, broccoli and sunflower seeds for lunch. My colleague also believed that there must be an optimal way to teach, that would maximise the learning outcome. I am doubtful that there is such a thing, bearing in mind the diversity of human experience. However I like […]
8 October 2012

## Judgment Calls in Statistics and O.R.

The one-armed operations researcher My mentor, Hans Daellenbach told me a story about a client asking for a one-armed Operations Researcher. The client was sick of getting answers that went, “On the one hand, the best decision would be to proceed, but on the other hand…” People like the correct answer. They like certainty. They like to know they got it right. I tease my husband that he has to find the best picnic spot or the best parking place, which involves us driving around considerably longer than I (or the children) were happy with. To be fair, we do […]
15 May 2012

## Excel in Statistics and Operations Research

I love spreadsheets The spreadsheet package is a wondrous thing. It has revolutionized a great many processes in the office, home and scientific research. It has affected the way we think and teach. It has enabled many more people to program and to build models, without even knowing it (and sometimes very badly). And, for better or worse, Excel has become the default spreadsheet package. I love spreadsheets and I love Excel.  I first became acquainted with Multiplan and Lotus-123 in 1984 as part of my graduate degree. It was amazing to see how versatile these spreadsheets were. Since then […]
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 […]
30 March 2012

## Operations Research and Statistics: BFF

As they say on Twitter: That silence after you tell someone you teach Operations Research (or Statistics). Those in the OR and Statistics communities know what conversation stoppers our disciplines are. When asked what subject I teach I take a punt and respond with “Operations Research”, “Management Science” or “Statistics”. “Operations Research” is met with incomprehension, “Management Science” with miscomprehension, and “Statistics” with thinly disguised antipathy. Apart from being undervalued, what the disciplines have in common is that we do practical stuff with numbers. The pedagogies of these disciplines have much in common. Operations Research and Management Science (which for […]
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 […]
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 […]