Thinking about the numbers
More students cheat in exams, and most are in Auckland, says the Herald.
This story combines two frequent StatsChat themes: denominators, and being careful about what was actually measured.
Auckland, as we have noted before, has a higher population than other regions. As you will recall, it’s about a third of the NZ population, so it looks like making up about 50% of those caught cheating is excessive. That’s the sort of work that the paper might do for you — as well as checking if 1/3 is still about right as the proportion of students sitting NCEA exams (it seems to be).
On similar lines, if you look just at the totals without denominators, you’ll miss some notable values. Northland had 25 students caught cheating, which is more than the much-larger Waikato and Canterbury regions. You’d expect about 10 at the national average rate and about 15 at the Auckland rate.
Much more important is the question of what proportion of those cheating were caught — to say things like
Again Central Plateau and the Cook Islands had no cheaters, and Wairarapa and Southland students were also honest
or to draw conclusions about trends over time assumes that you’re not missing many.
The story says
NZQA received 1,314,207 entries in NCEA and New Zealand Scholarship examinations from 145,464 students last year.
The 290 attempts at cheating that were caught come to just under 0.2% of students and just over 0.02% of exams. Maybe I’m just cynical, but I’d be surprised if the real rate was as low as one exam in a thousand, let alone five times lower.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »
Going further along with the question of “what was actually measured,” this is actually measuring enforcement, not behavior. E.g., perhaps it’s not that students are especially “honest” in the Central Plateau or Cook Islands. Maybe those students are more clever about their cheating; or maybe they have a low proctor:student ratio; or maybe the proctors there are less attentive.
8 years ago
Yes, exactly the point I was trying to make. Though in those cases the small numbers will also contribute to the lack of people being caught.
8 years ago
For a lot of kids these exams aren’t high stakes. They already have enough (or near enough) credits to pass NCEA level X before taking the exams. It means the incentive to cheat isn’t that high (compared to uni students where every exam pretty much matters).
And the kids who find exams tough, and are more likely to resort to cheating, have probably been directed into courses with more internal assessments anyway.
8 years ago