Posts from August 2012 (64)

Those are the basic questions you need to ask when reading, for example, that “almost half of Australian workers would rather quit a job than deal with office tension.”

Unfortunately, in the case the media release doesn’t answer the first question, and its answer to the second and third questions is

The 2012 R U OK? Australian Workplace Relationships Survey was developed in partnership with the Centre for Corporate Health, one of Australia’s leading workplace mental health service providers. 

Now, workplace mental health is an important issue, and for all I know it may be seriously neglected in Australia (I last worked there in 1995, but it was in a medical research centre, which probably isn’t typical).   That doesn’t mean mental-health advocates get a free pass on data quality — good facts matter more for important issues than for, say, whether we should wear pyjamas in the street.

The Centre for Corporate Health isn’t that enthusiastic about telling us how the survey was done: you need to subscribe to their research news to get in, and even then all they say is

The survey was distributed via online and paper-based to people across a wide range of Australian workplaces including both public and private sectors with all industry groups being represented.  The survey was open for a four week period. The total number of survey respondents was 1554.

which is not encouraging either in what it says or what it omits.  As far as I can tell, there’s no reason to believe the numbers are good estimates of anything about Australian employees as a whole.

The reason that organizations do these surveys seems to largely be marketing: having things that look (from the right angle, in poor light) like statistics makes it easier to get media coverage.  It shouldn’t: if we’re covering West Island business or health news, “R U OK Day” is important enough to be in the papers without needing unconvincing numerical camouflage to get it past the gate.

Wherever it wants.

Apparently, if the next Auckland volcano is in the worst possible location, 500000 people might need to be evacuated.  Even in a better location it will be no fun at all, with the only redeeming feature being that even Peter Thompson will have to concede that it’s not the best time to buy a house.   It’s good that research and planning is underway, so the mayor’s office will have a set of contingency plans filed under “V” for when the next eruption happens, but the need for public panic awareness is perhaps less than for the Alpine Fault.

From a statistical viewpoint, there are two factors that go into how much you should do to prepare for an emergency: how likely it is, and how much the preparation will help.   The earthquake wins on both of these: it’s about ten times as likely in the next 50 years, and we can do a lot more to reduce the damage.  With the Alpine Fault, we need to decide how much to spend on strengthening roads, bridges, and houses, and making water and sewer systems less likely to break.  Public discussion and pressure on the government are important.  On the other hand, if a river of molten rock heads south from One Tree Hill, or a chunk of tuff the size of a refrigerator lands on my roof, my house isn’t going to survive no matter how good the building standards are.

In terms of things we can actually influence, we might want to worry more about which bits of Auckland will be under water in 50-100 years, not which bits will be under lava.

Stuff has a story on today’s Big Wednesday lotto that doesn’t say anything obviously untrue or misleading.  I’m sure this isn’t a first, but it is rare enough to be notable.

The story doesn’t say anything about the odds, but in a sense that’s not the point: you don’t play the lottery to win, you play it to imagine winning.  To quote another statistician

The benefit to playing the lottery comes entirely between buying the ticket, and when the winner is revealed. During this interval, someone who has bought the ticket can entertain the idea that they might win, and pleasantly imagine how much better their life could be with the money, what they would do with it, etc. … If a $1 lottery ticket licenses even one hour of imagining a different life, I don’t see how people who spend $12 for two or three hours of such imagining at a movie theater, or $25 for ten hours at a bookstore, are in any position to talk.

The Herald has a good story today about attitudes to depression (unfortunately, only in Australia, but you can’t have everything).

Judging from the information on the beyondblue website about the 2001-2 survey, this is a real survey using random telephone sampling.  It’s asking important questions, and the Herald’s story summarises the worrying level of ignorance about depression among Aussies.  Notably, “62 per cent wrongly believe antidepressant medication is addictive” — the problem is the reverse, these medications are often difficult to keep taking for the necessary extended periods of time.

I said that I was judging from the information about the 2001-2 survey.  The webpage was last updated in 2006, and it says they are looking to do a second survey in 2004. Some more Googling suggests that they did a second survey in 2007-8, but I can’t find any results.  The media releases page doesn’t say anything, and the most recent release listed is from a month ago.

In the modern world it’s a pity that organisations can’t be more consistent about posting for the rest of us the information that they send out to the media. Then we might even have more success in persuading the media to link to it.

The Herald is reporting on Auckland Transport’s monthly report (you can find the reports here).  One of the recurring surprises in these reports is how high the punctuality figures are, and the Herald comments on these for some of the train services.

The bus punctuality statistics are even shinier

As a regular bus commuter it’s hard to imagine how these could be correct — and if they were, there would be no need for the real-time bus predictions, since the timetables would be more accurate than the predictions.

The solution is in the fine print: “Service punctuality for July 2012 was 99.24%, measured by the percentage of services which commence the journey within 5 minutes of the timetabled start time and reach their destination“.

Or, to quote Lewis Carroll’s Humpty Dumpty “When I use a word it means just what I choose it to mean — neither more nor less”

There’s an interesting story in the New York Times about queueing, a subject dear to the hearts of some of my colleagues.  In one sense queueing is a topic in probability theory, where you work out how long people might have to wait under various circumstances, leading to surprising but useful techniques such as metered on-ramps to motorways.  But it’s also a topic in applied psychology: if you get off your plane ten minutes before your bags arrive at the carousel, you’ll notice the wait less if you spend most of it walking. So that’s what the airports make you do.

As Alan Keegan points out in his Stat of the Week nomination, the Stats Department Facebook page was sporting a graph whose only redeeming feature is that it doesn’t even pretend to convey information.

To decide what to do with the graph, we are hosting a bogus poll:

Each week, we would like to invite readers of Stats Chat to submit nominations for our Stat of the Week competition and be in with the chance to win an iTunes voucher.

Here’s how it works:

• Anyone may add a comment on this post to nominate their Stat of the Week candidate before midday Friday August 24 2012.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of August 18 – 24 2012 inclusive.
• Quote the statistic, when and where it was published and tell us why it should be our Stat of the Week.

Next Monday at midday we’ll announce the winner of this week’s Stat of the Week competition, and start a new one.

(more…)

If you’d like to comment on or debate any of this week’s Stat of the Week nominations, please do so below!

From Stuff, under the headline “Public transport ‘good for your health'”

Waiting for public transport may seem dull, but new research shows daydreaming at the bus stop may be good for your mental health.

Wouldn’t it be nice to think so? Unfortunately, what the research actually found is a bit different:

Also, the ‘good for your health’ in the headline is claiming to be a quote, but the quote doesn’t appear in the story.