Posts filed under Just look it up (284)

I’m not going to get into the question of whether the NZ minimum wage should be higher; inequality and poverty are problems in NZ, but whether a minimum wage increase would help more than, say,  tax and benefit changes is not my area of expertise.  However, the question of how much the minimum wage has gone up is a statistical issue, and also appears to be controversial.

From April 2008 to April 2013, the minimum wage increased 14.6%. Inflation (2008Q1 to 2013Q1) was 11%. So, the minimum wage increased faster than inflation, and the proposed change will keep it increasing faster than inflation.

From whole-year 2008 to whole-year 2013, per-capita GDP increased 9.7%.  Mean weekly income increased 21%. Median weekly income increased 18.8%. Average household consumption expenditure increased 7.8%.

Increasing the 2008 minimum wage by 18.8%, following median incomes, would give $14.26, so the proposed minimum wage is at least close to keeping up with median income, as well as keeping ahead of economic growth. An increase to $14.50 would have basically kept up with mean income as well.

An important concern in using CPI is that housing might be a larger component of expenditure for people on minimum wage. However, since 2008 the CPI component for housing has increased more slowly than total CPI, so at least on a national basis and for this specific time frame that doesn’t change the conclusion.

[Sources: GDP at StatsNZ for GDP, household consumption expenditure. NZ Income Survey at StatsNZ for mean and median income. RBNZ for inflation]

As a final footnote: the story also mentions the Prime Minister’s salary. There really isn’t an objective way to compare changes in this to changes in the minimum wage. The PM’s salary has increased by a smaller percentage than the minimum wage since 2008, but the absolute increase is more than ten times that of a full-time minimum wage job.

From Stuff

But Tertiary Education Minister Steven Joyce has made it clear they are not going to get any more in this year’s Budget, and says students already have “one of the most generous support systems in the world”.

This is sufficiently vague that you can probably find a sense in which it’s true, and so could Mr Joyce’s counterparts in most other countries. For example, the Hong Kong system provides slightly larger loans and similar tuition subsidy, but charges (low) interest on the loans from day 1.  The US system allows much larger student loans and significant means-tested non-loan support, but provides much less public subsidy for tuition.  The UK system is more generous for students in low-income households but less generous for students in high-income households. It must be hard to find criteria where the NZ system is more generous than Germany or some other Western European countries, though.

What’s a bit more surprising is that the story treats inflation as basically a matter of opinion

From January 1999 to December 2008, they could borrow up to $150 a week. The limit has risen slowly since, and now stands at $173.56, which Mr Joyce says is in line with the rise in inflation.

vs

But Victoria University third-year student Annabelle Nichols said she and many of her friends were left in the red at the end of each week, and disagreed with Mr Joyce that living costs had kept pace with inflation.

If you look at the RBNZ online inflation calculator, you find that $150 in the first quarter of 1999 translates to $212.06 in the first quarter of 2014 using overall CPI, $217.38 using the food category, $346.62 using the housing category, $221.11 in the transport category, and $155.72 in the clothing category. Unless students are expected to spend the majority of their money on clothing, this seems inconsistent with Mr Joyce’s claim.

It’s possible that the Treasury has done specific living-cost modelling for students and that they do face lower effective inflation rates than the rest of the population, but given the location of many universities in places with expensive housing, that’s a bit surprising and would have been worth mentioning explicitly.

[Update: Mr Joyce was talking about just the period since 2008 ,when the loan limit stopped declining in real terms. That doesn’t affect my main point, which is that reporters shouldn’t treat inflation adjustment as a matter of opinion — they should check. Also, while 2008 is a relevant starting point for Mr Joyce, it’s not clear that it is for anyone else]

US GDP, measured by locations of businesses, from Reddit user atrubetskoy

Now, GDP isn’t really well-defined at that sort of spatial scale — employees and businesses and customers need not all live in the same small census area — and the data are old, but it still looks striking.

However, in this map, the orange areas have 50% of the US population

and since I used whole cities/counties as units, the orange areas could be made a lot smaller with a bit of effort, giving a better approximation to the GDP map.

From XKCD 

Prompted by Siouxsie Wiles’s report of talking to an anti-vivisectionist demonstrator, here are two charts from the annual report of the National Animal Ethics Advisory Committee. These are the people who monitor the use of animals in research, testing, and teaching in New Zealand.

The first chart shows what types of animals are used and what happens to them afterwards

More than half are sheep and cattle, mostly cattle, and mostly subjected to things like breeding or eating different types of feed.  There are quite a lot of mice used in biological research, though the numbers are decreasing (down 24% last year) partly because they are being replaced by zebrafish. None are monkeys.

About half of the research is commercial, with about a quarter at universities

Some people will still be opposed to livestock research because they’re opposed to livestock farming. Some people still  disapprove of the use of mice in biomedical research. But anyone who wants to campaign on those issues should be clear that those are the issues.

There are two basic sets of numbers related to unemployment: the number of people receiving unemployment benefit, which is easy to measure because the government knows who they are and makes them check in regularly; and the actual number of unemployed people, which is harder to measure and not perfectly well-defined.

Essentially everyone in the world uses the same definition of the unemployment rate: number of people looking for jobs divided by number of people who have jobs or are looking.  This isn’t ideal — it excludes people who’ve given up looking for jobs because there aren’t any — but it’s standard (and endorsed by, eg, the International Labour Organisation).  These numbers are estimated in two ways: by a survey of people (in New Zealand, the Household Labour Force Survey) and by data from businesses (LEED, and the Quarterly Employment Survey, in New Zealand)

In countries such as NZ, with well-run, independent national statistics agencies, the unemployment rate is hard to manipulate because the official statisticians won’t let you. The number on benefits is hard to manipulate because it’s easily measured.  So both numbers are trustworthy measurements of what they measure.  Sometimes, deliberately or accidentally, people confuse the two and say that unemployment has gone down when in fact it’s only the number on benefits that has gone down. If anyone sees examples of deliberate or reckless confusion of numbers on benefits and numbers unemployed, I’d welcome a note either to me or as a Stat-of-the-Week nomination, since it’s an important issue and an easy target for a post.

The current government is not, actually, particularly culpable in confusing these numbers; they prefer to take unjustified credit for the economic improvements following the global recession. For example, Paula Bennett has tended to talk about her ministry’s success in reducing the number of people on benefits (whether it’s true or  not, and whether it’s good or not).

So, I was surprised to see a column by Matt McCarten in the Herald accusing the Government of manipulating the unemployment statistics. He doesn’t mean that Stats New Zealand’s unemployment rate estimates have been manipulated — if he had evidence of that, it would be (minor) international news, not a local opinion column. He doesn’t mean that the published numbers on people receiving unemployment benefits are wrong, either. In fact, none of his accusations are really about manipulating the statistics. Mr McCarten is actually accusing the government of trying to push people off unemployment benefits. Since that’s one of the things Paula Bennett has publicly claimed credit for, it can hardly be viewed as a secret.

Personally, I’m in agreement with him on his actual point, but not on how it’s presented. Firstly, if the problem is the harassment of unemployed people to stop them claiming unemployment benefits, you should say that, not talk about manipulating statistics. And secondly, if there really is widespread public misunderstanding when politicians talk about the state of the economy, it’s hard to see who could be more to blame than the Herald.

The Herald (from the Daily Mail again, sigh) has a story about deadly mouthwash

Using mouthwash is a ‘disaster’ for health, increasing the risk of heart attacks and strokes, scientists are warning

In a small experimental study, 19 people who spent two weeks using a type of mouthwash not recommended for long-term use ended up with slightly higher blood pressure, by 2-3.5mmHg (or ‘mmgh’ as the story says). This was an uncontrolled study and everyone had the with-mouthwash and without-mouthwash experimental periods in the same order, so it could just have been a problem of experimental design, but it’s quite plausible that it’s true, and similar results have been found in the past.

What’s a bit surprising is that the story regards this as entirely a bad thing. The hypothesised reasons for the blood pressure difference is that the mouthwash kills bacteria in the mouth that make nitrite. You probably have heard of nitrite in previous Herald or Daily Mail stories.  It’s usually  described as a preservative for cured meats and is anathematised for its presumed potential to cause cancer. Even the introduction in the mouthwash research paper mentions that nitrite has traditionally been regarded as harmful and doesn’t give any of the recent evidence to the contrary.

There is also a widespread belief, though based on relatively weak evidence, that gum and mouth infections increase the risk of heart disease. Since the type of mouthwash being studied is recommended only for treatment, not for long-term use, it might easily decrease rather than increase the risk of heart disease if used as recommended.

It’s not obvious whether the benefits of mouthwash for chronic disease would outweigh the disadvantages, even if the research had studied the sorts of mouthwash (such as Listerine) intended for daily use. It is clear that the context, even context present in the abstract of the open-access research paper, is being ignored.

From Stuff, in a story about the new child-seat law not being broad enough

New Zealand has the third-highest child road death toll in the OECD, [a group of paediatric specialists] say in this month’s New Zealand Medical Journal.

This group are arguing for child restraints up to age 11, rather than age 7. As you know, I’m skeptical about claims like ‘third-highest’, so I looked at the NZ Medical Journal article. Its claim isn’t as strong

New Zealand compares unfavourably to other OECD countries for child traffic crash-related trauma[2]

And reference 2 is

2. New Zealand Transport Agency. Child Restraints Fact Sheet 07. Wellington: New Zealand Transport Agency, 2012

which, as you can see for yourself, doesn’t say anything at all about OECD comparisons. Presumably that’s just an editing error in the NZMJ paper, but as far as I can tell, none of the other references were OECD documents either.

The closest thing to OECD statistics I can find on the internets is this 2004 report, based on data from 1996-2000. It does show NZ third out of the set of countries with good enough data to be in the table, so I suspect it’s the source of the statistic. It’s a bit out of date, is nowhere near all of the current OECD, and is for all children 0-14, when the story is about needing child restraints for children 7-11.

The NZ data in the NZMJ article are more up-to-date (2000-2009), but are only for infants 0-4, who have been required to been in proper child seats for the last twenty years, so those data are irrelevant to the point being made.

So in this case the ‘3rd worse’ statistic is true(ish), but you can’t find it where Stuff attributes it, and you can’t find it where the NZMJ paper attributes it. And it’s based on data from a time when the overall NZ road toll (per capita) was twice what it is now, and the number of deaths in children under 14 was three times what it is now.

It’s a good thing the statistic isn’t really relevant to the campaign.

[update: in comments, Glen Koorey has found up-to-date information. New Zealand is currently 10th out of 29 countries in 0-14 road deaths]

Stuff has a story saying NZ is the worst in the world for bowel cancer, according to new World Health Organisation statistics. We’ve looked recently at claims that NZ was 2nd worst and 3rd worst in the world on various measures. They weren’t true. This one isn’t true either, though as with the previous stories, the truth is that NZ is still pretty bad.

The Herald story is more accurate, saying that Australia and New Zealand are the highest; that’s still a bit misleading because it just means the highest among regions, not countries, and because the region is dominated by the Australian data.

Since the stories are calling for more screening, it doesn’t really make sense to look at rates of diagnosis (‘incidence’). Incidence rates can only go up with increased screening, not down — the whole point of screening is to increase diagnosis. It makes more sense to looks at rates of death from bowel cancer (though the claims aren’t actually true for incidence, either).

If we use the new World Health Organisation statistics that both stories mention, and compare deaths from bowel cancer (as a fraction of the whole population, standardised for age) to all the countries for which the World Health Organisation has data, we find that NZ is second-worst in women (the gray line) and the rate of death is almost twice that for Australia.

In men, New Zealand is 25th-worst, and about 50% higher than Australia

Going for the ‘worst in the world’ title has led to missing a real public-health fact from the new statistics: NZ fatal bowel cancer rates compare much less favorably in women than in men, whether the comparison is to the whole world or to Australia.

The Council on Foreign Relations has built an interactive map showing outbreaks of the major vaccine-preventable diseases since mid-2008, based on news stories. Here’s the local map

The red circles are measles; the green are pertussis; blue are rubella.

There are two big limitations to the use of news stories as the source. The first is obvious from the map. That outbreak of 3500 pertussis cases in Western Australia wasn’t actually among the Ngaanyatjarra people of the Western Desert, where the circle is. It was mostly in Perth, but the story didn’t say that, just “Western Australia”.

The second limitation is that not everything gets reported. Here’s a map of more of the world

The small orange circles are  polio, and probably include every polio case diagnosed in the world. The larger, yellow circles include cholera and typhoid, and are just big outbreaks. The brown circles are mumps, which only seems to make the news in Europe and the Middle East. And there’s basically no pertussis reported in Africa or South Asia, because it’s underdiagnosed and not really news.

From the Herald

Log exports to China are driving an increase in the value of New Zealand’s forestry products – which has more than doubled in the past 20 years, according to figures from Statistics New Zealand.

and from Stats NZ, this infographic (click to embiggen, as usual)

In both the infographic and the Herald story there’s interesting information about changes in the makeup of NZ forestry exports (more logs, more to China), but in both cases the headline number is a bit misleading.

The change is from $1.9 billion in 1992 dollars to $4.5 billion in 2012 dollars. It’s not explicit that the dollar values are nominal, but they are — if I were a newspaper I’d say “evidence obtained by StatsChat under the Official Information Act”, which is to say I asked the always-helpful @StatisticsNZ twitter account.

My general view is that comparing nominal dollars twenty years apart is Not Even Wrong, but I have to admit it’s not obvious what the ideal adjustment would be. Consumer Price Index? Producer Price Index? Something that involves exchange rates? For that reason, here’s a selection of adjustments

• CPI: $1.9 billion in 1992 is $2.97 billion now, using the Reserve Bank’s calculator, which all journalists should have bookmarked
• PPI (outputs, all industries) $1.9b in 1992 is $3 billion now
• PPI (inputs, all industries) $1.9b in 1992 is $3.1 billion now
• As a proportion of GDP, forestry has fallen from 2.5% to 2.1%
• As a proportion of all exports, forestry has fallen from 10.4% to 9.4%

So, there’s a reasonable degree of agreement between measures that forestry has increased in value about 50% and has fallen slightly as a fraction of the economy. “More than doubled” doesn’t seem defensible.

(via @kiwieric)