David Bain’s guilt isn’t important

Is David Bain guilty of murder? No. That’s what a jury of our peers said on far better information than we now have. Did he kill people? Possibly. Does it matter? No.

Our justice system is designed to acquit people when we cannot be sure of their guilt. In its design there is an implicit judgment that errors of wrongful conviction are worse than errors of incorrect acquittal. Let’s think about that judgment. If you acquit someone who committed an offence then the cost to society is only the cost of their recidivism. Given uncertainty about their guilt, the cost is P(guilty) x P(reoffend) x (damage from reoffending). If you wrongfully convicted someone then the cost is P(not guilty) x (damage from imprisonment).

Suppose P(guilt) > P(not guilty) by a little, so the person is not convicted but we think they probably did it. Given that P(reoffend) is probably ~30%, that means that the damage from re-offending would have to be a lot higher than the damage from imprisonment to make it right to imprison the person. Most murderers do not reoffend by committing another homicide so we can class that outcome as highly unlikely. Given the cost to a person of imprisonment it does not seem unreasonable to make the value judgment that we have implicitly made in the design of our justice system.

On the basis of this approach, the question of whether Bain killed his family is only a curiousity. It has little bearing on whether he should be in jail, since any normal person’s answer to that question is based on a ‘balance of probabilities’ approach. It is commendable that the jury took their responsibilities seriously and did not fall into the trap of going with their gut.

Judith Tizzard down but not out?

I saw this in the Herald today and it got me thinking:

If Ms Lee wins the byelection, the next person on National’s list, Cam Calder, will enter Parliament.

Correct me if I’m wrong, but electorate seats aren’t supposed to change the total number of seats a party gets (unless you win more than your party vote like the Maori party did). Labour avoided the “Vote Twyford, get Tizard” dilemma when Phil Tyford stepped aside. But the fact that the Greens will split Labours vote and give the fresh face of Melissa Lea a chance raises an interesting possibility.

If Melissa Lea wins the seat then her title will change from list MP to MP for Mt Albert, but National won’t get any extra seats in parliament. This will leave a vacant seat that Labour will have to fill by taking the next person on their list.

So is it “vote Lea get Tizzard” after all?

Update: Seems that if National wins they do get another seat – so a byelection can change the proportionality of parliament. Seems weird!

John Key: big government conservatism?

Yesterday Nick Smith was thinking of taxing plastic bags. Today John Key threatened legislative intervention in an employment dispute. Now the government’s planning to spend $1.5b on telecommunications infrastructure. Now I’m not necessarily opposed to what they’re doing, but they do seem awfully interventionist for a right wing government.

How do people that voted for limited government and a retreat from the recent years of big government feel about all this? Is John Key living up to his promise to pull back from the days of the government ‘meddling’ in people’s lives?

Earth Hour

Earth Hour came and went over the weekend. There has been a lot of debate on the blogs over its merits: some support it, but many think it’s a waste of time. The goal of Earth Hour isn’t to save the world in one hour by reducing emissions from lighting; it’s to raise awareness of climate change. Given the amount of discussion about it that’s been generated I can only imagine that it’s been a huge success, regardless of whether everyone turned their lights off. I haven’t seen so much discussion of the best way to save power across the blogs and news media in ages!

Of course, any major environmental cause causes some crazies to come out of the woodwork. A few obtuse people have promoted the alternative Edison Hour, where people celebrate technology by turning their lights on. Read more

Cramer v Stewart: a bit disappointing

I just watched the Jim Cramer vs Jon Stewart showdown on The Daily Show and I’m just not as impressed as some others. Stewart’s real problem with Cramer seems to be that he should have known that the meltdown was coming and told his viewers. By advising them to buy stock that he should have known was bad he is jointly responsible for the fomentation that led to the stockmarket crash. There are two reasons why I’m not convinced: Read more

Aborting crime

Garth George at The Herald reckons that the root cause of all abuse and domestic violence is abortion. His position seems largely religious in nature so I can’t argue the point on his grounds. However, I was surprised to see reasonable-sounding commentators at Kiwiblog unsure whether George might be correct. This topic isn’t a new one and the most recent stab at it has been by the famous economist Steven Levitt and his co-author, John Donohue. In their paper they use statistical techniques to show that the drop in US crime in the ’90s was correlated with states’ legalisation of abortion. Read more