Tag: Statistics

A Science for Everyone, Community, Demography

Statistically Remote Doesn’t Mean Impossible

michaelmccurryphd

My post-Uvalde thoughts move toward hardening our own little school.  School shootings are always statistically unlikely.  The timeline at Uvalde shows that at 11:27, a teacher props the door open. It remains open for 6 minutes before the crazy little bastard enters the school.  He doesn’t close it – the door remains open and is the access point for police.  A safety protocol broke down.  The crazy little bastard had a six-minute window of opportunity.  Twenty-one people died and 17 more were wounded.  Six minutes.

In demography, our phrase is “Malthus only has to be right once.”  I listened to a Fed describing terrorist attacks  – “They have to get lucky once.  We have to get it right every day.”  The exercise showed how hard that was.  A teacher, secure in the misbelief that a statistically unlikely event wouldn’t happen, propped a door open.  For 6 minutes.  The crazy got in.  The statistically unlikely event happened.  We play poker hoping for statistically unlikely events to occur. 

It’s easy to look at the police failures – but the initial failure was the teacher who wedged the door open . . . secure in the belief that there was no risk in violating that simple safety protocol.  Staying alert, maintaining security against something that does not occur, day after day, is difficult. 

I can think of many situations where a teacher wouldn’t want to keep unlocking the door.  It’s Spring – the time when contracts are, or are not renewed.  We’ve had that this year at Trego – and seen a bit of hostility over it.  It gives me a perspective that, in Uvalde, the shooter gained access not through police failure, but through a teacher’s carelessness.  I can understand both carelessness and resentment.

I have forgotten the name of the teacher who left his female engineering students to be killed at the Montreal Polytechnique Massacre.  I hope he came to some sort of grips with his failure – I know I could not have accepted that decision had it been mine.  Perhaps the Uvalde teacher who spent 20 lives for easier access to the door can come to grips with that conduct.  I would hate to have to rationalize it had it been my blunder.

It is difficult to stay constantly on the alert for the statistically unlikely occurrence.  Years of boredom are eventually interrupted by a few minutes of stark terror.  Uvalde’s police, like Parkland’s, made poor choices – but the timeline shows that a teacher who propped the door open had the best opportunity to eliminate the shooter’s opportunity.  Was it just casual carelessness?  Was it carelessness coupled with resentment?  I do not know – but I have read the pricetag, and it was too high.

A Science for Everyone, Demography

Wells-Barnett Becoming Barbie

michaelmccurryphd

I note that Mattel is making a Barbie doll that honors Ida Wells-Barnett.

They note that she was a journalist, suffragette, and had a role in founding the NAACP – to me, her unusual strength was the use of statistics in her research on lynchings.  She deserves mention in her early role in social research and reliance on statistics.  Still, the article doesn’t include the quote that I find easy to remember:

I’m a Montanan.  My state’s legal tradition begins with vigilantes hanging a crooked sheriff and his minions.  In 1884, Granville Stuart organized another vigilance committee – now known as Stuart’s Stranglers – to end rustling.  In a short time, Stuart’s Stranglers killed at least 20 rustlers, and numbers up to 100 are written in some accounts.  By the end of the Summer, Granville Stuart was president of the Stockman’s Association.  Stuart’s activities, despite the poor record keeping, made 1884 the highest year for lynching white men in the US. (My readings suggest that the first recorded use of the numbers 3-7-77 was by Stuart’s Stranglers and not by the Vigilantes of Montana 20 years earlier)

Douglas Linder has published the data series Ida Wells started (maintained at Tuskegee) on lynchings by state and race. Clicking the link will give you an idea of how solid the lady’s research was – and how racist it was in some areas.

I’ll be looking for the Barbie – but I want mine to be holding a lever action Winchester.  She may not have been granted a graduate degree – but her work was important in developing American Sociology.

A Science for Everyone, Community

Other Vaccine Effectiveness

michaelmccurryphd

I got the Covid vaccine as soon as I could.  I think I might have been vaccinated earlier but for the manner in which the local government picked folks to vaccinate – I wasn’t sitting by the phone when the call came in, and that healthy, outdoors behavior put me a couple weeks later than I wanted.

I’m one of the people who was in line for the polio vaccine – and it wasn’t far out of the experimental stage.  A classmate who is with you in kindergarten one day, then gone, and the dread word polio makes for a willingness to step up for vaccination.  As a kid, I didn’t know that the Salk vaccine was only 65% effective against one strain, and about 90% effective against the others.  Multiplication and division were still challenges back then – but I got the vaccine.

I don’t need a perfect vaccine – the vaccine is to improve my odds.  I get flu vaccinations, and the table from CDC https://www.cdc.gov/flu/vaccines-work/past-seasons-estimates.html shows how that works.   The important part is “Adjusted Overall VE (%)

Table. Adjusted vaccine effectiveness estimates for influenza seasons from 2004-2018

CDC calculates vaccine effectiveness estimates through the U.S. VE Network

Influenza SeasonReferenceStudy Site(s)No. of PatientsAdjusted Overall VE (%)95% CI
2018-19Flannery 2020 WI, MI, PA, TX, WA3,2542921, 35
2017-18Rolfes 2019 WI, MI, PA, TX, WA8,4363831, 43
2016-17Flannery 2019 WI, MI, PA, TX, WA74104032, 46
2015-16Jackson 2017 WI, MI, PA, TX, WA68794841, 55
2014-15Zimmerman 2016 WI, MI, PA, TX, WA93111910, 27
2013-14Gaglani 2016 WI, MI, PA, TX, WA59995244, 59
2012-13McLean 2014 WI, MI, PA, TX, WA64524943, 55
2011-12Ohmit 2014 WI, MI, PA, TX, WA47714736, 56
2010-11Treanor 2011 WI, MI, NY, TN47576053, 66
2009-10Griffin 2011 WI, MI, NY, TN67575623, 75
2008-09UnpublishedWI, MI, NY, TN67134130, 50
2007-08Belongia 2011 WI19143722, 49
2006-07Belongia 2009 WI8715222, 70
2005-06Belongia 2009 WI34621-52, 59
2004-05Belongia 2009 WI76210-36, 40

The important thing is that, in 15 years of data, the best record the vaccine had was 60% effectiveness.  The worst was down to 10% effectiveness.  If I’m playing blackjack, and I can get a 10% edge, that’s good.  If I can get a 60% edge, that’s great.  I don’t expect a vaccine -particularly one that had a rushed development-  to be 100%.

Smallpox was ended with a vaccine that was about 95% effective – “Effective smallpox vaccines have a vaccinia titer of approximately 108 pock-forming units per mL, and more than 95% of individuals develop a ‘take’ with neutralizing antibodies after primary vaccination. “ It’s worth remembering that it took several centuries to develop that vaccine.

Vaccines are more a statisticians game, or a gambler’s science.  Today’s polio vaccine is about as close to 100% effective as you can get.  The vaccines aren’t magic bullets – but they are better bullets.  It may take a while – but I’m betting the Coronavirus vaccines will become increasingly effective.  The problem is that the scientists are working on better vaccines, and politicians and administrators are working on press releases.

Demography

Standard Deviation and Stable Genius

michaelmccurryphd

About three thoughts came together and gelled last week.  One was a headline that explained voter turnout in Wisconsin was 5 standard deviations from the mean.  The other was looking at Trump assessing himself as a “stable genius” and Biden’s frequent challenge of having a high IQ.  I realized that I don’t have to explain how to calculate a standard deviation – there is a chart that shows it all in terms of IQ, and it really simplifies matters. 

If you look at the linked table, on the scale that accepts 15 points as the standard deviation, an IQ score of 175 is 5 standard deviations above the norm.  To make that statement understandable, that’s one person out of 3,483,046.  Chances are that I have never met one, despite a career in science and the academy. 

Nasim Taleb writes “IQ” is a stale test meant to measure mental capacity but in fact mostly measures extreme unintelligence”, so let’s look at the IQ 25 – whom I also haven’t met.  0.0000287105% of the population would score below this mark.

Tierman’s classification for genius (based on a standard deviation of 16) was 140 and over – so if you check the chart, that’s one out of every 161 people.  Statistically, we should have four or five living within the Trego school district boundaries.  I don’t know what it takes to be a stable genius – maybe a horse?

IQ RangeClassification
140 and overGenius or near genius
120-140Very superior intelligence
110-120Superior intelligence
90-110Normal or average intelligence
80-90Dullness
70-80Borderline deficiency
Below 70Definite feeble-mindedness
Table developed by Tierman, source: IQ Comparison

When we look at Biden’s quote, “I think I probably have a much higher IQ than you do, I suspect.” and look at the chart in Talib’s paper, toward the bottom we see the range for “legal professions”.  Talib’s comment at the bottom is just as valid for attorneys as college professors.  It does add a bit of perspective.

Community, Demography

Covid’s Mask and Pascal’s Wager

michaelmccurryphd

According to the Internet Encyclopedia of Philosophy, “Blaise Pascal (1623-1662) offers a pragmatic reason for believing in God: even under the assumption that God’s existence is unlikely, the potential benefits of believing are so vast as to make betting on theism rational.” As a stats guy, I could write this from memory, as a scientist, I need to cite a source.

Pascal’s statistical argument is a gambler’s view of the universe – the cost of believing, of the ante, is so small compared to the infinite reward (the size of the pot).  I worked with an accountant who had a system for buying lottery tickets – his break from understanding Pascal was that both cost and reward in the statistics of lottery cards are finite – the odds really can be calculated.  Lotteries are a tax on people who don’t want to do the math.

Covid is also a game for statisticians.  It’s still at a point where we have a bunch of unknowns, but there are fewer unknowns than there were 6 months ago.  Then the Diamond Princess was a horrifying news story – now it is data, as taken from statista.com: “A total of 712 people were infected with COVID-19 on the Diamond Princess cruise ship – 567 passengers and 145 crew members. The cruise ship, which had more than 3,500 people on board, was quarantined for around two weeks. All passengers and crew members had finally disembarked the ship by March 1, 2020.”

Wikipedia shows 14 deaths among the 712 infected people on the Diamond Princess.  Somewhere right around 2%.  About the same as Texas and California, and lower than New York, New Jersey, and Massachusetts.

We’re still looking at less than perfect representative numbers – but Diamond Princess has provided some data:  roughly 20% of those exposed between January 20 and February 19 wound up infected.  In March, we had estimated R0 values from 1.5 to 3.5.  Now, we have Rt values (Average number of people who become infected by an infectious person with COVID-19 in the U.S. as of October 17, 2020).  Those numbers vary from 0.91 in Mississippi to 1.31 in New Mexico.  Montana scored 1.2. 

Generally speaking, in the absence of data, we have a tendency to assume the worst.  We have data now.  The actual infectivity is lower than the initial data – perhaps because the precautions have been effective, perhaps it is related to the fact that 80% of the people on Diamond Princess did not catch covid.  Correlation is not causation.  Causation is inferred from statistics, not proven.

This week, an article from the American Society of Hematology stated: “Blood type O may offer some protection against COVID-19 infection, according to a retrospective study. Researchers compared Danish health registry data from more than 473,000 individuals tested for COVID-19 to data from a control group of more than 2.2 million people from the general population. Among the COVID-19 positive, they found fewer people with blood type O and more people with A, B, and AB types.”

Making statistics personal is a challenge – data suggests that my risk factors are increased by age (70), height (6’3”), asthma, and diabetes.  How much we don’t know – for neither my asthma nor the diabetes scores particularly high.  My risk factors are reduced by my blood type.  So let’s look at masking.

My mask is like Pascal’s wager – it seems logical that any level of masking will reduce transmission.  The question is: “How much?”  I don’t have that answer.  Does my mask protect me significantly?  When I have been in surgery, the surgeons and medical staff were masked to protect me.  Similarly, is my mask to protect others?   Business Insider offers an article comparing mask effectiveness, but cautions that “Mask studies should be taken with a grain of salt.”  My mask is like Pascal’s wager – and I hope wearing it adds a sense of security. It costs me little to wear it.

Demography

Talking about Risk

michaelmccurryphd

A headline read, “What if we could live for a million years?”  My casual answer was “not a chance.”  Even if we could eliminate aging and disease, we still have to consider risk.  The National Safety Council reports 1.25 deaths for every 100 million miles of highway travel.  Assume 10,000 miles per year of highway travel, in the first thousand years of life, you’re up to 10 million miles.  That turns out to be a 1 out of 8 chance of dying – just from highway transportation.  The National Geographic gives odds of being struck by lightning as 1 in 700,000 each year, and one in 3,000 over a lifetime.  Increase the lifetime to that same 1,000 years, and the odds go up.  We live in a risk society, and often ignore that fact. 

I know a guy who survived a grizzly mauling, and I’ve known one who died from wasp stings.  Even in Trego, I encounter more wasps than bears.  CDC stats show 89 people who died from bee stings in 2017.  It isn’t a large risk – but 80% of the fatalities are male.  Bee stings are a greater risk to the male half of the population. 

Just about every endeavor includes misunderstood risks.  In 2018, the police fatality rate was 13.7 per 100,000 (bureau of labor and statistics).  CDC shows the 2017 fatality rate for farmers was 20.4 per 100,000.  BLS shows a rate of 132.7 per 100,000 loggers in 2015.  CDC shows bartenders have a higher on job fatality rate than police.  In some places policing is a relatively risky job – but in farm country and logging country it seems fairly safe.  Here’s the link to more data if this interests you.

When we started looking a Covid-19, we didn’t have the statistical data to calculate risk.  Now, we do have some data – and we’re seeing disagreements, mostly because folks see risks differently.  As I write, RealClearPolitics shows 5,746,272 confirmed cases in the US, and 177,424 deaths, yielding a 3.09% confirmed case fatality rate.  Still, that number goes from 8.25% in New Jersey to 0.79% in Utah.  We have solid numbers – but not numbers that allow us to calculate risk.  When we look at the charts that include age, we can begin to calculate risk – 70 is higher risk than 40.  80 is even higher.  New York numbers suggest that dense populations and public transportation increase risk – but not enough to calculate. 

The numbers let us develop ordinal data about covid risk – ranking things as more or less, rather than develop statistical data.  At 70, I’m at more risk than someone who is 50. The age data is good enough to develop some statistics – but the comorbidities that make it covid fatal mask that. Riding mass transportation is more dangerous than driving a car alone.  The virus doesn’t differentiate between bars and churches – open spaces are safer than crowded enclosed spaces.  So far we know that Covid is a bit more infectious than flu, and less infectious than measles.  Ordinal data. Buzz Hollander, a physician in Hawaii, has a good, readable article on covid at this site.