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ERIC Number: EJ906685
Record Type: Journal
Publication Date: 2010
Pages: 7
Abstractor: ERIC
Reference Count: 7
ISSN: ISSN-0819-4564
Model Fitting for Predicted Precipitation in Darwin: Some Issues with Model Choice
Farmer, Jim
Australian Senior Mathematics Journal, v24 n2 p6-12 2010
In Volume 23(2) of the "Australian Senior Mathematics Journal," Boncek and Harden present an exercise in fitting a Markov chain model to rainfall data for Darwin Airport (Boncek & Harden, 2009). Days are subdivided into those with precipitation and precipitation-free days. The author abbreviates these labels to wet days and dry days. It is suggested that a 2 state Markov chain model may be suitable for modelling the pattern of wet and dry days. In this article, the author discusses the Markov chain model and the relevance of this model to Australian high school curriculum. In their "What went wrong?" section, Boncek and Harden suggest that their first attempt at fitting the model failed because the transition probabilities were not constant, with 2008 being a particularly dry year. They then refit the model using 2007-2008 data, giving parameters that more closely match the 10 year average, and conclude this Markov chain model is appropriate. This misses the major reason that the Markov chain model is not appropriate, which is that the transition probabilities vary enormously "within" each year. The author explains the inappropriateness of the Markov chain model and presents two perspectives on what really went wrong with the model. He also examines the type of calculations that could justify a Markov chain model.
Australian Association of Mathematics Teachers (AAMT). GPO Box 1729, Adelaide 5001, South Australia. Tel: +61-8-8363-0288; Fax: +61-8-8362-9288; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Evaluative
Education Level: High Schools
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Identifiers - Location: Australia