Stats Chat

There are stories on Stuff and the Herald about early studies of a potential Alzheimer’s drug. There was also a story on One News last night, but the video doesn’t seem to be up, and there’s one on Newshub.

The drug, adacanumab, reduced amyloid plaque buildup in people with early-stage disease. According to the most widely believed theory about Alzheimer’s, that could slow or even stop the progression of disease. And, as the stories say, if the treatment turns out to be successful in future trials, it will be a game changer.

We’ve never had an successful treatment that modifies the disease process in Alzheimer’s, but we’ve had a range of promising candidates that failed as soon the test went beyond biochemistry to improvements in memory or the ability to handle daily life.  Adacanumab might be different. Let’s hope so.

Auckland Transport released new patronage data, and FigureNZ tidied it up to make it easily computer-readable, so I thought I’d look at some of it.  What I’m going to show is a decomposition of the data into overall trends, seasonal variation, and random stuff just happening. As usual, click to embiggen the pictures.

First, the trends: rides are up.

It’s hard to see the trend in ferry use, so here’s a version on a log scale — meaning that the same proportional trend would look the same for all three modes of transport

Train use is increasing (relatively) faster than bus or ferry use.  There’s also an interesting bump in the middle that we’ll get back to.

Now, the seasonal patterns. Again, these are on a logarithmic scale, so they show relative variation

The clearest signal is that ferry use peaks in summer, when the other modes are at their minimum. Also, the Christmas minimum is a bit lower for trains: to see this, we can combine the two graphs:

It’s not surprising that train use falls by more: they turn the trains off for a lot of the holiday period.

Finally, what’s left when you subtract the seasonal and trend components:

The highest extra variation in both train and ferry rides was in September and October 2011: the Rugby World Cup.

From the Herald (from the Daily Mail)

Patients should be warned about the dangers of chemotherapy after research showed that cancer drugs are killing up to 50 per cent of patients in some UK hospitals.

That’s almost completely untrue.

Firstly, the research looked at deaths from any cause within 30 days of starting treatment, and did not claim these were all due to chemotherapy. Secondly,  the 50% figure was in one hospital. Thirdly, it was for a subset of one particular type of cancer.  And, the conclusion from the news story cannot be found anywhere in the research paper.

The researchers do think that chemotherapy is probably being used suboptimally in some of the hospitals, including the one where about 5 out of 10 of the patients being treated ‘with curative intent’ for lung cancer died within 30 days. That hospital stood out, despite the tiny numbers, because the average death rate across all hospitals for similar patients was about 3%.

As the researchers say

The identification of hospitals with significantly higher 30-day mortality rates will promote review of clinical decision making in these hospitals.

It probably will, but that doesn’t tell us much about risks here on the other side of the world

Team Ratings for Round 26

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.

Performance So Far

So far there have been 184 matches played, 117 of which were correctly predicted, a success rate of 63.6%.
Here are the predictions for last week’s games.

Predictions for Round 26

Here are the predictions for Round 26. 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.

Team Ratings for Round 3

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.

Performance So Far

So far there have been 14 matches played, 12 of which were correctly predicted, a success rate of 85.7%.
Here are the predictions for last week’s games.

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.

Team Ratings for Round 5

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.

Performance So Far

So far there have been 15 matches played, 9 of which were correctly predicted, a success rate of 60.0%.
Here are the predictions for last week’s games.

Predictions for Round 5

Here are the predictions for Round 5. 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.

From the Northern Advocate

An unprecedented run of success in selling winning Lotto second division winning tickets has a Whangarei store on tenterhooks expecting an even bigger win soon.

Now, in one sense this is rubbish: lotto is drawn randomly. Previous wins can’t function as an outward and visible sign of a inward propensity to sell lucky tickets, because there is no such thing.

On the other hand, statistically, you would expect a store that has sold a lot of winning tickets in the past to sell a lot of winning tickets in the future. That’s because a store that has sold a lot of winning tickets has probably just sold a lot of tickets.

A ‘lucky’ lotto vendor will usually be one that’s made a lot of profits for Lotto New Zealand. As to whether its customers are lucky, well, you don’t tend to see stories like this set in Herne Bay or Thorndon.

• 538 has a new Twitter bot, censusAmericans, which tweets little descriptions of individuals from what I think must be the American Community Survey, though they describe it as the census.

• “Relaxing Privacy Vow, WhatsApp Will Share Some Data With Facebook” (NY Times). “Relaxing” is such a nice way to put that, but as various people have pointed out, this is what happens when companies build up volumes of data.

• A nice app for exploring how differences in some measurement (‘biomarker’) between groups of people (fail to) translate into reliable tests

• Our introductory statistics online course is starting up again: October 3

• The Spinoff and Figure.NZ are launching a “Chart of the Week” feature

• I’ve mentioned this before, but since it was mesmerising visitors to our Courses and Careers Day this weekend, Nathan Yau’s animation of what people do all day is worth linking again

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 September 2 2016.
• Statistics can be bad, exemplary or fascinating.
• The statistic must be in the NZ media during the period of August 27 – September 2 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.

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Team Ratings for Round 25

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.

Performance So Far

So far there have been 176 matches played, 111 of which were correctly predicted, a success rate of 63.1%.
Here are the predictions for last week’s games.

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.