Posts filed under General (535)

August 30, 2014

Flying vs driving costs

To complement the Herald’s flying Air New Zealand vs driving costs for various NZ cities, I thought I’d work out similar comparisons for the Pacific Northwest, where I used to live.  It’s a reasonable comparison — both have relatively sparsely spaced cities, though the roads are better there.

I used Alaska Airlines for the flying costs; they are the main local airline in the region. The costs are the cheapest flight on a random weekday in September — there will be some days and seasons when it’s cheaper or more expensive.  The driving cost  is based on the actual driving distance, not the straight-line distance, and uses the cost per mile specified for business tax deductions.

from to distance (km) US$flying US$driving NZ$flying NZ$driving
1 Seattle Portland 278 368 97 438 116
2 Seattle Spokane 449 398 157 474 187
3 Seattle Calgary 1146 455 401 542 478
4 Seattle Kelowna 507 440 177 524 211
5 Portland Kelowna 785 487 275 580 327
6 Spokane Calgary 698 581 244 692 291

 

The results aren’t that different from NZ, except that the impact of competition is clearer: the Seattle–Calgary flight is much less expensive that you’d predict from the others, probably because there lots of one-stop alternatives via Vancouver.

August 28, 2014

Briefly

‘Dodgy use of data’ edition [Background: the Washington Post is the serious DC paper. The Washington Times, not so much]

  • From the Washington Post  “But really, is it possible that more than 1 in 6 people in France could “back” Islamic State? When you look at the numbers closely, something doesn’t add up.”
  • From journalism/editing blog HeadsUp: “Too bad a clear conscience and a pure heart can’t turn correlation into cause, no matter what your first named source says.”
  • From economics blog TVHE:  For example, [Tourism Industry Association New Zealand] claims that 15%of Upper Hutt residents’ jobs depend on the tourism industry, while only 9% of residents’ jobs in Queenstown-Lakes District depend on tourism.”

 

 

August 26, 2014

NRL Predictions for Round 25

Team Ratings for Round 25

The basic method is described on my Department home page. I have made some changes to the methodology this year, including shrinking the ratings between seasons.

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
Roosters 11.22 12.35 -1.10
Rabbitohs 10.50 5.82 4.70
Cowboys 10.23 6.01 4.20
Storm 7.48 7.64 -0.20
Sea Eagles 5.54 9.10 -3.60
Broncos 4.60 -4.69 9.30
Warriors 1.54 -0.72 2.30
Panthers 1.15 -2.48 3.60
Dragons 0.25 -7.57 7.80
Bulldogs -2.89 2.46 -5.40
Knights -4.94 5.23 -10.20
Eels -4.96 -18.45 13.50
Titans -6.12 1.45 -7.60
Raiders -9.08 -8.99 -0.10
Sharks -11.55 2.32 -13.90
Wests Tigers -14.75 -11.26 -3.50

 

Performance So Far

So far there have been 176 matches played, 99 of which were correctly predicted, a success rate of 56.2%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Bulldogs vs. Wests Tigers Aug 21 30 – 10 15.40 TRUE
2 Eels vs. Sea Eagles Aug 22 22 – 12 -9.50 FALSE
3 Broncos vs. Knights Aug 23 48 – 6 8.40 TRUE
4 Rabbitohs vs. Cowboys Aug 23 10 – 22 8.40 FALSE
5 Warriors vs. Roosters Aug 24 12 – 46 0.60 FALSE
6 Sharks vs. Raiders Aug 24 12 – 22 4.70 FALSE
7 Dragons vs. Titans Aug 24 34 – 6 7.20 TRUE
8 Panthers vs. Storm Aug 25 10 – 24 0.90 FALSE

 

Predictions for Round 25

Here are the predictions for Round 25. 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 Bulldogs vs. Rabbitohs Aug 28 Rabbitohs -8.90
2 Broncos vs. Dragons Aug 29 Broncos 8.90
3 Knights vs. Eels Aug 30 Knights 4.50
4 Raiders vs. Wests Tigers Aug 30 Raiders 10.20
5 Roosters vs. Storm Aug 30 Roosters 8.20
6 Warriors vs. Titans Aug 31 Warriors 12.20
7 Sea Eagles vs. Panthers Aug 31 Sea Eagles 8.90
8 Cowboys vs. Sharks Sep 01 Cowboys 26.30

 

ITM Cup Predictions for Round 3

Team Ratings for Round 3

Here are the team ratings prior to Round 3, along with the ratings at the start of the season. I have created a brief description of the method I use for predicting rugby games. Go to my Department home page to see this.

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
Canterbury 19.69 18.09 1.60
Tasman 9.09 5.78 3.30
Wellington 8.20 10.16 -2.00
Auckland 3.31 4.92 -1.60
Counties Manukau 2.19 2.40 -0.20
Hawke’s Bay 1.75 2.75 -1.00
Waikato 0.77 -1.20 2.00
Otago -1.29 -1.45 0.20
Taranaki -3.68 -3.89 0.20
Southland -5.25 -5.85 0.60
Bay of Plenty -8.38 -5.47 -2.90
Northland -9.09 -8.22 -0.90
Manawatu -9.45 -10.32 0.90
North Harbour -9.93 -9.77 -0.20

 

Performance So Far

So far there have been 14 matches played, 10 of which were correctly predicted, a success rate of 71.4%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 North Harbour vs. Southland Aug 21 21 – 25 -0.70 TRUE
2 Waikato vs. Canterbury Aug 22 27 – 58 -14.90 TRUE
3 Hawke’s Bay vs. Taranaki Aug 22 29 – 26 9.40 TRUE
4 Northland vs. Wellington Aug 23 35 – 5 -13.30 FALSE
5 Counties Manukau vs. Otago Aug 23 29 – 25 7.50 TRUE
6 Manawatu vs. Auckland Aug 24 7 – 35 -8.80 TRUE
7 Bay of Plenty vs. Tasman Aug 24 27 – 56 -8.90 TRUE

 

Predictions for Round 3

Here are the predictions for Round 3. 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 Waikato vs. Taranaki Aug 27 Waikato 8.50
2 Canterbury vs. Northland Aug 28 Canterbury 32.80
3 Wellington vs. Manawatu Aug 29 Wellington 21.60
4 Counties Manukau vs. Hawke’s Bay Aug 30 Counties Manukau 4.40
5 Southland vs. Otago Aug 30 Southland 0.00
6 North Harbour vs. Waikato Aug 30 Waikato -6.70
7 Taranaki vs. Bay of Plenty Aug 31 Taranaki 8.70
8 Auckland vs. Tasman Aug 31 Tasman -1.80

 

Currie Cup Predictions for Round 4

Team Ratings for Round 4

The basic method is described on my Department home page. I have made some changes to the methodology this year, including shrinking the ratings between seasons.

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
Western Province 5.29 3.43 1.90
Sharks 4.37 5.09 -0.70
Lions 2.37 0.07 2.30
Cheetahs -0.28 0.33 -0.60
Blue Bulls -3.43 -0.74 -2.70
Griquas -8.02 -7.49 -0.50
Pumas -8.15 -10.00 1.80
Kings -11.47 -10.00 -1.50

 

Performance So Far

So far there have been 12 matches played, 11 of which were correctly predicted, a success rate of 91.7%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Pumas vs. Griquas Aug 22 33 – 15 3.00 TRUE
2 Blue Bulls vs. Kings Aug 23 30 – 25 14.20 TRUE
3 Western Province vs. Lions Aug 23 27 – 14 7.10 TRUE
4 Sharks vs. Cheetahs Aug 23 19 – 16 10.60 TRUE

 

Predictions for Round 4

Here are the predictions for Round 4. 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 Pumas vs. Sharks Aug 29 Sharks -7.50
2 Griquas vs. Cheetahs Aug 30 Cheetahs -2.70
3 Blue Bulls vs. Western Province Aug 30 Western Province -3.70
4 Kings vs. Lions Aug 30 Lions -8.80

 

August 22, 2014

California drought visualisation

 

From XKCD. Both the data and the display technique are worth looking at

california

 

Presumably you could do something similar with New Zealand, which is roughly the same shape.

August 20, 2014

NRL Predictions for Round 24

Team Ratings for Round 24

The basic method is described on my Department home page. I have made some changes to the methodology this year, including shrinking the ratings between seasons.

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
Rabbitohs 12.31 5.82 6.50
Cowboys 8.42 6.01 2.40
Roosters 8.31 12.35 -4.00
Sea Eagles 7.28 9.10 -1.80
Storm 6.12 7.64 -1.50
Warriors 4.45 -0.72 5.20
Panthers 2.51 -2.48 5.00
Broncos 1.76 -4.69 6.40
Dragons -1.60 -7.57 6.00
Knights -2.10 5.23 -7.30
Bulldogs -3.37 2.46 -5.80
Titans -4.27 1.45 -5.70
Eels -6.70 -18.45 11.80
Sharks -10.20 2.32 -12.50
Raiders -10.43 -8.99 -1.40
Wests Tigers -14.28 -11.26 -3.00

 

Performance So Far

So far there have been 168 matches played, 96 of which were correctly predicted, a success rate of 57.1%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Rabbitohs vs. Broncos Aug 14 42 – 16 12.60 TRUE
2 Eels vs. Bulldogs Aug 15 16 – 18 2.00 FALSE
3 Raiders vs. Dragons Aug 16 16 – 34 -1.30 TRUE
4 Storm vs. Sharks Aug 16 48 – 6 16.40 TRUE
5 Wests Tigers vs. Roosters Aug 16 4 – 48 -12.80 TRUE
6 Knights vs. Warriors Aug 17 28 – 22 -4.00 FALSE
7 Titans vs. Sea Eagles Aug 17 12 – 15 -8.10 TRUE
8 Panthers vs. Cowboys Aug 18 23 – 22 -2.10 FALSE

 

Predictions for Round 24

Here are the predictions for Round 24. 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 Bulldogs vs. Wests Tigers Aug 21 Bulldogs 15.40
2 Eels vs. Sea Eagles Aug 22 Sea Eagles -9.50
3 Broncos vs. Knights Aug 23 Broncos 8.40
4 Rabbitohs vs. Cowboys Aug 23 Rabbitohs 8.40
5 Warriors vs. Roosters Aug 24 Warriors 0.60
6 Sharks vs. Raiders Aug 24 Sharks 4.70
7 Dragons vs. Titans Aug 24 Dragons 7.20
8 Panthers vs. Storm Aug 25 Panthers 0.90

 

ITM Cup Predictions for Round 2

Team Ratings for Round 2

Here are the team ratings prior to Round 2, along with the ratings at the start of the season. I have created a brief description of the method I use for predicting rugby games. Go to my Department home page to see this.

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
Canterbury 19.69 18.09 1.60
Wellington 8.20 10.16 -2.00
Tasman 6.79 5.78 1.00
Auckland 3.31 4.92 -1.60
Counties Manukau 2.19 2.40 -0.20
Hawke’s Bay 1.75 2.75 -1.00
Waikato 0.77 -1.20 2.00
Otago -1.29 -1.45 0.20
Taranaki -3.68 -3.89 0.20
Southland -5.25 -5.85 0.60
Bay of Plenty -6.08 -5.47 -0.60
Northland -9.09 -8.22 -0.90
Manawatu -9.45 -10.32 0.90
North Harbour -9.93 -9.77 -0.20

 

Performance So Far

So far there have been 7 matches played, 4 of which were correctly predicted, a success rate of 57.1%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Taranaki vs. Counties Manukau Aug 14 9 – 9 -2.30 FALSE
2 Southland vs. Bay of Plenty Aug 15 34 – 23 3.60 TRUE
3 Otago vs. North Harbour Aug 16 28 – 14 12.30 TRUE
4 Canterbury vs. Auckland Aug 16 48 – 9 17.20 TRUE
5 Wellington vs. Waikato Aug 16 25 – 37 15.40 FALSE
6 Tasman vs. Hawke’s Bay Aug 17 35 – 15 7.00 TRUE
7 Northland vs. Manawatu Aug 17 23 – 28 6.10 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 North Harbour vs. Southland Aug 21 Southland -0.70
2 Waikato vs. Canterbury Aug 22 Canterbury -14.90
3 Hawke’s Bay vs. Taranaki Aug 22 Hawke’s Bay 9.40
4 Northland vs. Wellington Aug 23 Wellington -13.30
5 Counties Manukau vs. Otago Aug 23 Counties Manukau 7.50
6 Manawatu vs. Auckland Aug 24 Auckland -8.80
7 Bay of Plenty vs. Tasman Aug 24 Tasman -8.90

 

Currie Cup Predictions for Round 3

Team Ratings for Round 3

The basic method is described on my Department home page. I have made some changes to the methodology this year, including shrinking the ratings between seasons.

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
Western Province 4.90 3.43 1.50
Sharks 4.87 5.09 -0.20
Lions 2.77 0.07 2.70
Cheetahs -0.78 0.33 -1.10
Blue Bulls -2.84 -0.74 -2.10
Griquas -7.10 -7.49 0.40
Pumas -9.07 -10.00 0.90
Kings -12.06 -10.00 -2.10

 

Performance So Far

So far there have been 8 matches played, 7 of which were correctly predicted, a success rate of 87.5%.

Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Sharks vs. Pumas Aug 15 34 – 17 19.30 TRUE
2 Western Province vs. Blue Bulls Aug 16 41 – 17 11.10 TRUE
3 Lions vs. Kings Aug 16 60 – 19 17.00 TRUE
4 Cheetahs vs. Griquas Aug 16 34 – 27 12.00 TRUE

 

Predictions for Round 3

Here are the predictions for Round 3. 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 Pumas vs. Griquas Aug 22 Pumas 3.00
2 Blue Bulls vs. Kings Aug 23 Blue Bulls 14.20
3 Western Province vs. Lions Aug 23 Western Province 7.10
4 Sharks vs. Cheetahs Aug 23 Sharks 10.60

 

August 17, 2014

“Evidence”-based sentencing

Predictive risk scores for re-offending are increasingly used in the US. An opinion piece in the New York Times argues this is bad

The basic problem is that the risk scores are not based on the defendant’s crime. They are primarily or wholly based on prior characteristics: criminal history (a legitimate criterion), but also factors unrelated to conduct. Specifics vary across states, but common factors include unemployment, marital status, age, education, finances, neighborhood, and family background, including family members’ criminal history.