Monday 22 December 2014

Scoring my political predictions

Earlier in the year I made a couple of political predictions just to give it a go, and now that we're at the tail end of the year it's time to do some scoring to see whether I should invest more in iPredict or just give up as a political pundit.

- National will win a third term, but barely (with the support of at least two minor parties).
True - National almost won by themselves, but they ended up taking Maori, ACT, and United Future along with them just to be safe.

- Labour will score less than 30%, with the Greens gaining ground and going past 15%.
Half-True - Labour scored 25.13% in the final count, but the Greens only scored 10.7%. I was really hopeful that the Green vote would grow, but it wasn't to be.

- ACT won't be back in Parliament in 2015. Peter Dunne will barely win his Ohariu seat again.
Half-True - Both of them got back in, and I guess I shouldn't doubt the insanity of Epsom. Peter Dunne won his seat by 710 votes.

- Colin Craig won't win his electorate seat, and the Conservatives won't get enough votes to get into Parliament.
True - If I may say so, thankfully. After analysing some of their policies, such as their tax reforms, I would be quite worried if they had any say in determining where our country goes.

- Another new minor party will capture the interest of the nation in 2014, not including Kim Doctom's party or The Civilian Party. There will be ridiculously huge support for Kim Dotcom's party, particularly among young people, even though Kim Doctom won't be standing himself (he'll just bankroll everything).
Partly True - can I call the New Zealand Independent Coalition a new minor party (that didn't really capture the interest of the nation but oh well)? Internet MANA collected 1.42% of the vote, which I wouldn't call ridiculously huge support, although 34,000 votes is still quite a lot.

- Winston Peters will continue to be alive and kicking... and New Zealand First will continue to be a thorn in the side of the government, whoever it happens to be.
True - After being earmarked by all news agencies as being a potential kingmaker, National ended up doing much better than most people expected, and Winston is doomed to harass the Speaker and be outraged at the government for another three years.

- Voter turnout will be above 75% again on the back of increased youth participation.
True - well, the voter turnout was reported at 77%, which is still kind of disappointing really. I was hoping it would be more than 80%.

- The media will keep stoking the fires of discussion about the National Party leader succession, but John Key will happily stay on for another three years.
True - the media discussed it for a little bit, throwing names around the mix but JK has said that he'd be happy to even stay on for a fourth term if the country wants him to.

- At least two more MPs will be out of Parliament before the general election.
True - I'll call Shane Jones and John Banks as the two MPs who quit.

- A rising star in the National Party will get relegated into obscurity for doing/saying something stupid while campaigning.
True - Judith Collins was a rising star right? She was being tipped for the National Party leadership and while most of the things she did were before the campaigning started, she was probably one of the people who suffered the most from the backlash of Dirty Politics.

- More cracks will appear in the Labour caucus as they are led by a guy that most of them don't support.
True - While to the public the caucus were all fully behind David Cunliffe, the election result and the subsequent leadership contest showed that even though Cunliffe may have had support from the unions and membership, at the end of the day he has to lead a team of MPs and candidates to effect action and change.

- A Green Party list reshuffle will lead to some discontent, and cause at least one current MP to be outside the top 15 (and therefore unlikely to return in 2015).
True - A reshuffle in May saw both good and bad, but unfortunately for Steffan Browning he moved from 10 to 16 and was left out of Parliament after the election.
[Edit: turns out I got this wrong because I used a list from just after the election - Steffen Browning did get in after specials were counted.]

- David Parker will not be the next Finance Minister. He's a nice guy, but no.
True - Nope. Sorry David (Parker).

- Genesis Energy will be floated and it'll be the last of the asset sales as National prays for the issue to go away before the election.
True - It was floated reasonably quietly and then no one talked about asset sales at the election.

- Paula Bennett and/or the Ministry of Social Development will be part of another major scandal in 2014.
Partly True - while it wasn't necessarily a scandal that attracted the attention of the national media like privacy infringements of the past, Bennett certainly made some aggressive and unhelpful calls this year, from saying that throwing money at those on welfare doesn't alleviate poverty to saying that we don't need to investigate historical sexual abuse to attacking beneficiaries such as Sarah Wilson for speaking out about the failures of our social welfare system. *sigh*

- Another major TPP leak will bring the issue to the forefront of the public's attention.
True - Wikileaks has continued to leak chapters of the TPP, and the sage just never seems to end. More protests occurred this year throughout the country but it never really became a heavy election topic, probably something to do with the timing of it all.

- Kim Dotcom will not be extradited to the US (in 2014).
True - While general sentiment was pro-Dotcom a few years ago, he's burnt a lot of bridges this year. Public sentiment shouldn't affect court cases, but I'd guess that a few more people would be happier to see him extradited now than at the beginning of the year.

- New Zealand will win a Security Council seat (yay!).
True - yay! Now we wait to see what impact we can have on the Security Council, as it continues to grapple with worsening crises around the world.

So overall I think I did pretty well, even if some of the predictions were, to be frank, a bit of a cop out given that they were kinda obvious to any political observer. 2014 has been a bit of a tumultuous year in politics, and personally I wish a lot of it hadn't happened. We could have had a nice interesting (for me) election based on policy and how the parties wanted to improve the country, but instead we got stuck in a vicious cycle of dirty politics and political scandal. The optimist hopes that it will be better in the future; the realist knows that it'll probably be more of the same.

Thursday 18 December 2014

School Deciles and Wealth

Firstly, apologies for the lack of posting recently. Between exams and my self-imposed holiday after the end of undergraduate university, I've tried to stay away from spending too much time writing for the blog. However, the Ministry of Education released new decile rankings a few weeks ago. Almost 1,500 out of 2,600-odd schools experienced changes to their decile, with funding implications in 2015. There were a couple of interesting changes, such as Carmel College, Auckland Grammar School, and Macleans College, some of the best (public) schools in Auckland, dropping from decile 10 to decile 9. This sparked a thought that I couldn't help but investigate.

School deciles are often conflated with the wealth of the area surrounding the school. It commonly presents in the form of assumptions such as "That school in [suburb x] is decile 10, therefore [suburb x] is really well off." This assumption isn't necessarily unfounded or wrong. Public schools are zoned, meaning that each school has a surrounding geographic area where the majority of students come from. Parents generally want their kids to have the best education possible, pushing up demand (and therefore prices) for property in zones with schools that are perceived to be good. The people who can afford the more expensive homes tend to have more wealth and higher incomes. Deciles for schools are based on the socio-economic status of the area surrounding the school. Therefore, high deciles = wealthier families in the area, and statements like "All the kids that go to [good school] are rich" seem reasonable.

This common chain of logic is almost correct except for when it comes to how the deciles are calculated - the Ministry of Education explains here that the process of assigning deciles is a lot more complicated than just figuring out how rich the area surrounding each school is.

Firstly, the decile isn't based on the immediate geographic area surrounding the school - schools are required to provide the MoE with a list of addresses of their students, which makes sense since we probably want the decile calculation to be based on the students who are actually attending the school, whether they are in-zone or not. Since data on individual houses cannot be provided by Statistics NZ for privacy reasons, the MoE uses the finest data granularity possible - the meshblock, which is a group of roughly 50 households.

Secondly, the socio-economic indicator used by the Ministry of Education is based on more than just household income - there are actually five factors, including the occupation of the parents, household crowding, educational qualifications of adults, and percentage of adults on government income support such as unemployment or sickness benefits. While some of these factors influence each other (leading to co-correlation), these other factors play a part in influencing school deciles.

Thirdly, the definition of deciles means that they're relative - each decile from 1 to 10 represents 10% of the schools in the country. The MoE ranks all of the schools based on the socio-economic indicator from before, and divides it into 10 groups to assign the deciles. This means that the bottom of decile 10 is not all that dissimilar to the top of decile 9. The discrete levels used in deciles subconsciously imply step changes between the deciles, but the schools actually exist on a spectrum rather that at individual steps. I should note here that the MoE does divide the deciles even further into smaller steps when determining the funding per student for each school.

What does this all mean? Well it begins to suggest that the assumption of "high decile = wealthy geographical area" may not be true. The data that is used to build the deciles is much broader than that, and the discrete nature of deciles makes them poor measures of something as continuous as wealth anyway. But how bad is this assumption? To find out, I pulled school decile data for 2014 and census data for 2013, and tried to analyse how well school decile predicts median household income of the surrounding area. A different way of stating this hypothesis would be "given the decile for a particular school, how likely is it that the area surrounding that school is rich or poor?"

I did this for three different granularities of geographic area - Territorial Local Authority or Local Board (TLA), Ward, and Census Area Unit (CAU). Each of these areas is smaller (and thus a finer granularity) than the previous one. I used a regression analysis to determine how much the income variation was explained by the decile variation.

In all three cases, the decile only explains a relatively small amount of the variation in the household median income. There certainly is a statistical relationship at each granularity, but it is weakly positive. Since there's only one variable on each axis the strength of relationship would be the same if we flipped the axes around. We can therefore also say that household median income only explains a small amount of the variation in the school deciles. The rest of the variation is explained by the other factors used by the Ministry of Education as well as some contribution from the discrete nature of deciles.

Even just a cursory look at the graphs without the statistical analysis shows that there is a lot of overlap in median household income inbetween the deciles. While outliers are to be expected, the wide spread of median household income within each decile surprised me a little, and without the statistical analysis it would be easy to conclude that the household income makeup of each decile is the same.

So what does this all mean? The upshot is that school deciles are a poor indicator of the wealth or richness of the people who live in the geographic vicinity of the school. Just because a school is decile 10 does not mean that the people living near it are rich, and just because a school is decile 1 does not mean that the people living near it are poor.

Of course, median household income itself cannot 100% accurately predict overall socio-economic status of the area, and when people say "rich" or "poor" they may not just be meaning income. Median is also probably a bad measure of the overall rich/poor-ness of an area given the potential income spread/range, but it's what Statistics NZ provided. However, this analysis gives a brief insight into just how bad some of our assumptions around school deciles are. That's all I really wanted to know - can we say with confidence that a high decile school has high income families around it? No.