January 23, 2013

Where denominators don’t help

There’s a report saying that NZ smartphone users are the 7th most at risk for attacks by cybercriminals.  We could ask the usual questions about whether this survey is worth the paper it’s not written on, but this time those are left as an exercise for the reader [as is often the case, the last sentence of the Herald’s story is especially informative].

An unusual problem with the ranking is

The ranking was based on the percentage of Android apps rated as high-risk over the total number of apps scanned per country.

The use of a percentage rather than a total here seems to make no sense.  If you have a high-risk app on your phone, it doesn’t become low-risk just because you also have lots of other apps.

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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 »