July 19, 2016

Good news

Three pieces of statistical good news:

First, from the New York Times,  several serious diseases are getting less common, and we don’t really know why. Heart disease rates have been falling for my whole lifetime. More recently, rates of dementia have been going down (though the number of cases is going up, because there are more old people). Hip fractures are down. And now colon cancer is getting less common.  In all these cases there are well-understood contributing factors, but these aren’t enough to explain the decrease (except perhaps for heart disease).

Violence is also down: in the specific politically-relevant case, fewer US police officers have been shot during the Obama presidency than the equivalent periods of Clinton, Bush, or Reagan.

And finally, in US states where medical marijuana has been legalised, there are fewer prescriptions written for other competing drugs. (Washington Post, original research paper). This is most dramatic in prescriptions for painkillers: marijuana is competing successfully against opioid narcotics.

Polls over petitions

I mentioned in June that Generation Zero were trying to crowdfund an opinion poll on having a rail option in the Auckland’s new harbour crossing.

Obviously they’re doing this because they think they know what the answer will be, but it’s still a welcome step towards evidence-based lobbying.

The results are out, in a poll conducted by UMR. Well, a summary of the results is out, in a story at The Spinoffand we can hope the rest of the information turns up on Generation Zero’s website at some point. A rail crossing is popular, even when its cost is presented as part of the question:

HarbourCrossingGraph

The advantage of proper opinion polls over petitions or other sort of bogus polls is the representativeness.  If 50,000 people sign a petition, all you know is that the true number of supporters is at least 50,000 (and maybe not even that).  Sometimes there will be one or two silent supporters for each petition vote (as with Red Peak); sometimes many more; sometimes fewer.

Petitions do have the advantage that you feel as if you’re doing something when you sign, but we can cope without that: after all, we still have social media.

July 18, 2016

Briefly

  • Lovely rant about Aloe vera gel and sunburn: “Listen, you antiscience monster: These people who sell aloe vera are stealing from you. As of 2004, the market for finished aloe products was worth $110 billion. The aloe barons are taking your money and building gigantic aloe palaces and not helping your sunburn at all. They are probably taking long soaks in great big hot tubs for which you helped pay. And they’re probably wearing lots of sunscreen, too, because they know nothing in their cabinets can heal sunburn.”

Stat of the Week Competition: July 16 – 22 2016

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 22 2016.
  • Statistics can be bad, exemplary or fascinating.
  • The statistic must be in the NZ media during the period of July 16 – 22 2016 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…)

July 13, 2016

Super 18 Predictions for Round 17

Team Ratings for Round 17

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
Crusaders 11.21 9.84 1.40
Highlanders 8.31 6.80 1.50
Hurricanes 7.57 7.26 0.30
Chiefs 7.51 2.68 4.80
Lions 6.45 -1.80 8.30
Waratahs 5.75 4.88 0.90
Brumbies 3.42 3.15 0.30
Stormers 2.39 -0.62 3.00
Sharks 1.78 -1.64 3.40
Bulls -2.60 -0.74 -1.90
Blues -2.74 -5.51 2.80
Cheetahs -7.63 -9.27 1.60
Jaguares -8.76 -10.00 1.20
Rebels -9.82 -6.33 -3.50
Force -11.05 -8.43 -2.60
Reds -11.45 -9.81 -1.60
Sunwolves -21.76 -10.00 -11.80
Kings -21.82 -13.66 -8.20

 

Performance So Far

So far there have been 126 matches played, 93 of which were correctly predicted, a success rate of 73.8%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Blues vs. Brumbies Jul 08 40 – 15 -5.90 FALSE
2 Reds vs. Chiefs Jul 08 5 – 50 -10.90 TRUE
3 Lions vs. Kings Jul 08 57 – 21 31.20 TRUE
4 Crusaders vs. Rebels Jul 09 85 – 26 20.40 TRUE
5 Waratahs vs. Hurricanes Jul 09 17 – 28 4.00 FALSE
6 Force vs. Stormers Jul 09 3 – 22 -8.10 TRUE
7 Bulls vs. Sunwolves Jul 09 50 – 3 19.90 TRUE
8 Sharks vs. Cheetahs Jul 09 26 – 10 12.50 TRUE
9 Jaguares vs. Highlanders Jul 09 8 – 34 -11.30 TRUE

 

Predictions for Round 17

Here are the predictions for Round 17. 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 Blues vs. Waratahs Jul 15 Waratahs -4.50
2 Reds vs. Rebels Jul 15 Reds 1.90
3 Sharks vs. Sunwolves Jul 15 Sharks 27.50
4 Crusaders vs. Hurricanes Jul 16 Crusaders 7.10
5 Highlanders vs. Chiefs Jul 16 Highlanders 4.30
6 Brumbies vs. Force Jul 16 Brumbies 18.00
7 Stormers vs. Kings Jul 16 Stormers 27.70
8 Cheetahs vs. Bulls Jul 16 Bulls -1.50
9 Jaguares vs. Lions Jul 16 Lions -11.20

 

NRL Predictions for Round 19

Team Ratings for Round 19

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 11.41 4.41 7.00
Cowboys 8.96 10.29 -1.30
Sharks 6.75 -1.06 7.80
Bulldogs 5.05 1.50 3.60
Broncos 3.55 9.81 -6.30
Raiders 2.95 -0.55 3.50
Eels 0.91 -4.62 5.50
Sea Eagles -0.31 0.36 -0.70
Roosters -1.29 11.20 -12.50
Panthers -2.11 -3.06 0.90
Warriors -2.22 -7.47 5.20
Titans -3.70 -8.39 4.70
Dragons -3.94 -0.10 -3.80
Rabbitohs -3.95 -1.20 -2.70
Wests Tigers -4.57 -4.06 -0.50
Knights -15.81 -5.41 -10.40

 

Performance So Far

So far there have been 130 matches played, 80 of which were correctly predicted, a success rate of 61.5%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Eels vs. Roosters Jul 08 22 – 18 5.40 TRUE
2 Bulldogs vs. Wests Tigers Jul 09 32 – 22 9.60 TRUE
3 Panthers vs. Sharks Jul 10 10 – 26 -4.20 TRUE
4 Raiders vs. Cowboys Jul 11 26 – 12 -5.70 FALSE

 

Predictions for Round 19

Here are the predictions for Round 19. 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 Dragons vs. Titans Jul 15 Dragons 2.80
2 Sea Eagles vs. Warriors Jul 16 Sea Eagles 1.90
3 Rabbitohs vs. Broncos Jul 16 Broncos -4.50
4 Knights vs. Storm Jul 17 Storm -24.20
5 Panthers vs. Eels Jul 17 Eels -0.00
6 Roosters vs. Sharks Jul 18 Sharks -5.00

 

July 11, 2016

Stat of the Week Competition: July 9 – 15 2016

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 15 2016.
  • Statistics can be bad, exemplary or fascinating.
  • The statistic must be in the NZ media during the period of July 9 – 15 2016 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…)

July 6, 2016

Super 18 Predictions for Round 16

Team Ratings for Round 16

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
Crusaders 8.89 9.84 -0.90
Highlanders 7.43 6.80 0.60
Hurricanes 6.67 7.26 -0.60
Waratahs 6.65 4.88 1.80
Lions 6.17 -1.80 8.00
Chiefs 5.46 2.68 2.80
Brumbies 5.27 3.15 2.10
Stormers 1.74 -0.62 2.40
Sharks 1.57 -1.64 3.20
Bulls -4.23 -0.74 -3.50
Blues -4.59 -5.51 0.90
Cheetahs -7.42 -9.27 1.90
Rebels -7.50 -6.33 -1.20
Jaguares -7.88 -10.00 2.10
Reds -9.40 -9.81 0.40
Force -10.40 -8.43 -2.00
Sunwolves -20.13 -10.00 -10.10
Kings -21.54 -13.66 -7.90

 

Performance So Far

So far there have been 117 matches played, 86 of which were correctly predicted, a success rate of 73.5%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Chiefs vs. Crusaders Jul 01 23 – 13 -5.30 FALSE
2 Brumbies vs. Reds Jul 01 43 – 24 18.10 TRUE
3 Sunwolves vs. Waratahs Jul 02 12 – 57 -19.70 TRUE
4 Hurricanes vs. Blues Jul 02 37 – 27 15.40 TRUE
5 Rebels vs. Stormers Jul 02 31 – 57 -2.40 TRUE
6 Cheetahs vs. Force Jul 02 30 – 29 7.80 TRUE
7 Kings vs. Highlanders Jul 02 18 – 48 -24.30 TRUE
8 Lions vs. Sharks Jul 02 37 – 10 5.50 TRUE
9 Jaguares vs. Bulls Jul 02 29 – 11 -2.10 FALSE

 

Predictions for Round 16

Here are the predictions for Round 16. 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 Blues vs. Brumbies Jul 08 Brumbies -5.90
2 Reds vs. Chiefs Jul 08 Chiefs -10.90
3 Lions vs. Kings Jul 08 Lions 31.20
4 Crusaders vs. Rebels Jul 09 Crusaders 20.40
5 Waratahs vs. Hurricanes Jul 09 Waratahs 4.00
6 Force vs. Stormers Jul 09 Stormers -8.10
7 Bulls vs. Sunwolves Jul 09 Bulls 19.90
8 Sharks vs. Cheetahs Jul 09 Sharks 12.50
9 Jaguares vs. Highlanders Jul 09 Highlanders -11.30

 

NRL Predictions for Round 18

Team Ratings for Round 18

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 11.41 4.41 7.00
Cowboys 10.32 10.29 0.00
Sharks 5.92 -1.06 7.00
Bulldogs 5.02 1.50 3.50
Broncos 3.55 9.81 -6.30
Raiders 1.59 -0.55 2.10
Eels 1.03 -4.62 5.70
Sea Eagles -0.31 0.36 -0.70
Panthers -1.28 -3.06 1.80
Roosters -1.41 11.20 -12.60
Warriors -2.22 -7.47 5.20
Titans -3.70 -8.39 4.70
Dragons -3.94 -0.10 -3.80
Rabbitohs -3.95 -1.20 -2.70
Wests Tigers -4.54 -4.06 -0.50
Knights -15.81 -5.41 -10.40

 

Performance So Far

So far there have been 126 matches played, 77 of which were correctly predicted, a success rate of 61.1%.
Here are the predictions for last week’s games.

Game Date Score Prediction Correct
1 Roosters vs. Bulldogs Jun 30 20 – 24 -3.30 TRUE
2 Broncos vs. Storm Jul 01 6 – 48 0.80 FALSE
3 Warriors vs. Titans Jul 02 27 – 18 4.80 TRUE
4 Wests Tigers vs. Panthers Jul 02 34 – 26 -1.60 FALSE
5 Sharks vs. Eels Jul 02 34 – 24 7.50 TRUE
6 Raiders vs. Knights Jul 03 29 – 25 23.00 TRUE
7 Rabbitohs vs. Cowboys Jul 03 0 – 20 -9.80 TRUE
8 Sea Eagles vs. Dragons Jul 04 36 – 6 3.00 TRUE

 

Predictions for Round 18

Here are the predictions for Round 18. 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 Eels vs. Roosters Jul 08 Eels 5.40
2 Bulldogs vs. Wests Tigers Jul 09 Bulldogs 9.60
3 Panthers vs. Sharks Jul 10 Sharks -4.20
4 Raiders vs. Cowboys Jul 11 Cowboys -5.70

 

July 4, 2016

Run away

There’s a piece in the Herald, from The Conversation (with attribution, and links intact, yay!), on the supposed brain benefits of running.  There’s an interesting evolutionary speculation that humans, specifically, might benefit from running because of our pre-history of long-distance running to hunt

The growth of new brain cells in the hippocampus and the enhancement of spatial memory that is brought on by endurance running is basically an evolutionary safety net for when you have outrun your knowledge, when you have run so far that you no longer know where you are and you need to learn, fast. It is a mechanism that makes information uptake easiest when historically you might have been tired, lost, and at your most vulnerable.

There’s also some actual evidence on brain cell growth

What the new research tells us is that it is not just any exercise that will create new brain cells for you. In the study by Finnish researchers, they discovered that only certain kinds of exercise are likely to result in the growth of new brain cells in adults.

As you will find if you follow the link (but not from reading the story), that research is in rats. Unless their ancestors, too, pursued their prey across miles of African savannah, it rather tends to undermine the evolutionary argument.