The TRIPSE - example problem Next Page | TOC | Home

Leading Causes

Marnie, a graduate student in Behavioural Sciences, uses a well validated rating scale to assess the prevalence of antisocial behaviour amongst Grade 3 students in all 5 elementary schools in the city. She finds that 27 out of 246 can be labelled "antisocial". Closer attention to the data shows that 7 out of the 27 students come from the same private school (The Vanguard).

Millicent, who is Marnie's roommate, suggests that she approach the problem epidemiologically by listing the school as a "risk factor" for the production of antisocial behaviour. She shows Marnie how to tabulate the data to estimate an odds-ratio. 

  Antisocial behaviour Normal behaviour
The Vanguard 7 18
All other schools 20 201

The estimated odds-ratio is large enough to cause concern. At Millicent's urging, Marnie decides to explore the issues further.

She finds that the school is a private one, run by a Society dedicated to improving the lot of women. Many of the mothers who send their children to the school are adamant about self-reliance. To that end they not only promote self-medications with herbals rather than prescription drugs, but also advocate that women undertake training in using firearms. A large number of them are practising artists and craftspeople. Marnie is also intrigued to find that 5 of the 7 students on her list live in the same large house — an older building which had been extensively remodelled several years ago by the parents themselves. The house not only has several pottery studios but also an attached indoor shooting range.


Next Page | TOC | Home