Posts from July 2017 (30)

July 25, 2017

Currie Cup Predictions for Round 2

Team Ratings for Round 2

The basic method is described on my Department home page.

Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Current Rating Rating at Season Start Difference
Lions 6.74 7.41 -0.70
Cheetahs 5.16 4.33 0.80
Western Province 3.30 3.30 0.00
Blue Bulls 2.05 2.32 -0.30
Sharks 1.32 2.15 -0.80
Pumas -9.97 -10.63 0.70
Griquas -11.34 -11.62 0.30

 

Performance So Far

So far there have been 3 matches played, 2 of which were correctly predicted, a success rate of 66.7%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Cheetahs vs. Sharks Jul 21 47 – 12 6.70 TRUE
2 Griquas vs. Blue Bulls Jul 22 45 – 51 -9.40 TRUE
3 Pumas vs. Lions Jul 23 43 – 36 -13.50 FALSE

 

Predictions for Round 2

Here are the predictions for Round 2. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Game Date Winner Prediction
1 Lions vs. Griquas Jul 28 Lions 22.60
2 Sharks vs. Pumas Jul 29 Sharks 15.80
3 Cheetahs vs. Western Province Jul 30 Cheetahs 6.40

 

July 24, 2017

Stat of the Week Competition: July 22 – 28 2017

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 July 28 2017.
  • Statistics can be bad, exemplary or fascinating.
  • The statistic must be in the NZ media during the period of July 22 – 28 2017 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…)

Stat of the Week Competition Discussion: July 22 – 28 2017

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

July 21, 2017

This time we might be number one

So, Radio NZ has a story based on a commentary at YaleGlobal on homelessness.

The point of the YaleGlobal piece is that homelessness is increasing as the world gets more urbanised, and that it’s really hard to measure because people define it differently and because some countries don’t want it measured accurately. Overall

Based on national reports, it’s estimated that no less than 150 million people, or about 2 percent of the world’s population, are homeless. However, about 1.6 billion, more than 20 percent of the world’s population, may lack adequate housing.

There’s obviously a lot of room for variation in definitions.

This report isn’t Yale research, really. It’s based on OECD figures, which are reported by governments: the OECD HC3-1 indicator (PDF).  The number for New Zealand is 41705, which we’ve seen last year in the NZ media. It comes from the 2013 census, and was estimated by researchers at Otago.  The NZ homelessness number is high for at least three reasons.  First, NZ uses a very broad definition of homelessness. Second, we’re pretty good at honest data collection. And, third, we’ve got a serious homelessness problem (and have had for a while).

The Government is right to say that the international figures aren’t all comparable. Some countries only count people who are sleeping rough. Others include people in shelters or emergency accomodation. We include a lot more. The Herald story from last year quotes an Otago researcher, Kate Amore

“If the homeless population were a hundred people, 70 are staying with extended family or friends in severely crowded houses, 20 are in a motel, boarding house or camping ground, and 10 are living on the street, in cars, or in other improvised dwellings.”

From that tally, a few countries don’t even count all of the 10; some don’t count all of the 20; many don’t count the 70 —  and some aren’t very good at counting.

Here’s a set of charts I made based on a crude classification of definitions from the OECD HC3-1 report. The numbers on the axis are in % of the population.

homeless

Even within the top panel, NZ, the Czech Republic, and Australia have the broadest definitions. The HC3-1 report says

Australia, the Czech Republic and New Zealand report a relatively large incidence of homelessness, and this is partly explained by the fact that these countries adopt a broad definition of homelessness. In Australia people are considered as homeless if they have “no other options to acquire safe and secure housing are without shelter, in temporary accommodation, sharing accommodation with a household or living in uninhabitable housing”. In the Czech Republic the term homeless covers “persons sleeping rough (roofless), people who are not able to procure any dwelling and hence live in accommodation for the homeless, and people living in insecure accommodation and people staying in conditions which do not fulfil the minimum standards of living […]”. In New Zealand homelessness is defined as “living situations where people with no other options to acquire safe and secure housing: are without shelter, in temporary accommodation, sharing accommodation with a household or living in uninhabitable housing.”

I think the New Zealand definition is a good one for measuring the housing deprivation problem, but it’s not good for international comparisons.

On the other hand, the comparison to Australia is pretty fair, and there’s at least no evidence that anywhere else has higher rates.  To some extent we have an apples vs oranges comparison, but that doesn’t stop us concluding it’s a bad apple.

July 20, 2017

Currie Cup Predictions for Round 1

Team Ratings for Round 1

The basic method is described on my Department home page.

Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Current Rating Rating at Season Start Difference
Lions 7.41 7.41 0.00
Cheetahs 4.33 4.33 -0.00
Western Province 3.30 3.30 0.00
Blue Bulls 2.32 2.32 -0.00
Sharks 2.15 2.15 0.00
Pumas -10.63 -10.63 -0.00
Griquas -11.62 -11.62 0.00

 

Predictions for Round 1

Here are the predictions for Round 1. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Game Date Winner Prediction
1 Cheetahs vs. Sharks Jul 21 Cheetahs 6.70
2 Griquas vs. Blue Bulls Jul 22 Blue Bulls -9.40
3 Pumas vs. Lions Jul 23 Lions -13.50

 

Avocado denominators

Time magazine’s website has had at least seven stories about avocado on toast since May. The most recent one says

Square, a tech company that helps businesses process credit card payments, crunched data from sellers around the U.S. and found that Americans are spending nearly $900,000 per month on crusty bread topped with mashed green fruit.

What’s impressive about that number is how unimpressive it is.  The US is a big place. Even if we only count millennials, there are 80 million of them, so we’re talking about an average of 1 cent each per month.

But it gets worse from there. The story talks about the 50-fold increase since 2014. That’s an increase in sales handled by Square, an expanding business. Neither Time nor Square seems to have made any attempt to look at sales from comparable businesses over time, which Square could have done easily.

The whole avocado-toast thing only makes sense as a synecdoche for an eating-out lifestyle, so accurate data about avocado on toast isn’t really going to be very helpful for anything important. Even so, it’s possible for innumerate presentations of inaccurate data to be less helpful.

July 19, 2017

Super 18 Predictions for the Qualifiers

Team Ratings for the Qualifiers

The basic method is described on my Department home page.

Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Current Rating Rating at Season Start Difference
Hurricanes 17.12 13.22 3.90
Lions 14.57 7.64 6.90
Crusaders 13.83 8.75 5.10
Highlanders 11.28 9.17 2.10
Chiefs 9.88 9.75 0.10
Brumbies 2.30 3.83 -1.50
Stormers 1.48 1.51 -0.00
Blues -0.22 -1.07 0.90
Sharks -0.26 0.42 -0.70
Waratahs -3.81 5.81 -9.60
Bulls -4.96 0.29 -5.20
Jaguares -5.03 -4.36 -0.70
Force -6.97 -9.45 2.50
Cheetahs -9.63 -7.36 -2.30
Reds -9.92 -10.28 0.40
Kings -12.08 -19.02 6.90
Rebels -15.29 -8.17 -7.10
Sunwolves -19.38 -17.76 -1.60

 

Performance So Far

So far there have been 135 matches played, 101 of which were correctly predicted, a success rate of 74.8%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Highlanders vs. Reds Jul 14 40 – 17 25.50 TRUE
2 Rebels vs. Jaguares Jul 14 29 – 32 -6.70 TRUE
3 Kings vs. Cheetahs Jul 14 20 – 21 1.30 FALSE
4 Sunwolves vs. Blues Jul 15 48 – 21 -20.90 FALSE
5 Chiefs vs. Brumbies Jul 15 28 – 10 10.70 TRUE
6 Hurricanes vs. Crusaders Jul 15 31 – 22 6.50 TRUE
7 Force vs. Waratahs Jul 15 40 – 11 -3.60 FALSE
8 Sharks vs. Lions Jul 15 10 – 27 -10.60 TRUE
9 Bulls vs. Stormers Jul 15 33 – 41 -2.20 TRUE

 

Predictions for the Qualifiers

Here are the predictions for the Qualifiers. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Game Date Winner Prediction
1 Brumbies vs. Hurricanes Jul 21 Hurricanes -10.80
2 Crusaders vs. Highlanders Jul 22 Crusaders 6.10
3 Lions vs. Sharks Jul 22 Lions 18.30
4 Stormers vs. Chiefs Jul 22 Chiefs -4.40

 

NRL Predictions for Round 20

Team Ratings for Round 20

The basic method is described on my Department home page.

Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Current Rating Rating at Season Start Difference
Storm 7.40 8.49 -1.10
Cowboys 6.45 6.90 -0.50
Broncos 3.58 4.36 -0.80
Panthers 2.97 6.08 -3.10
Sea Eagles 2.87 -2.98 5.80
Sharks 2.76 5.84 -3.10
Raiders 2.21 9.94 -7.70
Roosters 1.07 -1.17 2.20
Eels -0.41 -0.81 0.40
Rabbitohs -1.22 -1.82 0.60
Titans -1.60 -0.98 -0.60
Warriors -2.42 -6.02 3.60
Dragons -2.63 -7.74 5.10
Bulldogs -4.36 -1.34 -3.00
Wests Tigers -6.78 -3.89 -2.90
Knights -11.93 -16.94 5.00

 

Performance So Far

So far there have been 136 matches played, 81 of which were correctly predicted, a success rate of 59.6%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Warriors vs. Panthers Jul 14 22 – 34 0.60 FALSE
2 Raiders vs. Dragons Jul 14 18 – 14 9.20 TRUE
3 Knights vs. Broncos Jul 15 22 – 34 -12.00 TRUE
4 Titans vs. Sharks Jul 15 30 – 10 -4.60 FALSE
5 Sea Eagles vs. Wests Tigers Jul 16 28 – 16 13.40 TRUE
6 Rabbitohs vs. Cowboys Jul 16 10 – 23 -2.50 TRUE

 

Predictions for Round 20

Here are the predictions for Round 20. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Game Date Winner Prediction
1 Broncos vs. Bulldogs Jul 20 Broncos 11.40
2 Roosters vs. Knights Jul 21 Roosters 16.50
3 Sharks vs. Rabbitohs Jul 21 Sharks 7.50
4 Panthers vs. Titans Jul 22 Panthers 8.10
5 Raiders vs. Storm Jul 22 Storm -1.70
6 Cowboys vs. Warriors Jul 22 Cowboys 12.90
7 Dragons vs. Sea Eagles Jul 23 Sea Eagles -2.00
8 Wests Tigers vs. Eels Jul 23 Eels -2.90

 

July 17, 2017

Stat of the Week Competition: July 15 – 21 2017

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 July 21 2017.
  • Statistics can be bad, exemplary or fascinating.
  • The statistic must be in the NZ media during the period of July 15 – 21 2017 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…)

Stat of the Week Competition Discussion: July 15 – 21 2017

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