Author Archives: gmcdavid

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About gmcdavid

Retired IT professional with a wide range of interests. Married. Three sons, two with autistic-spectrum disorders and the third being transgender with Ehlers-Danlos syndrome. From Chicago but now living in the Twin Cities metro, Minnesota. Episcopalian. Carleton College (BA 1972, physics) and Stanford University (MS 1974, Applied Physics; MS 1976 Statistics).

Monday Night Irish Class, April 15, 2013

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Irish Class, April 15, 2013

Rang Gaeilge, 15ú lá mí Aibreáin 2013

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Fadas: áéíóúÁÉÍÓÚ

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Seamróg: D’fhéadfadh sé a bheith níos measa

Is féidir go mbeadh an Taoiseach buidéal uisce beatha a thabhairt don Uachtarán. Ní fadhb é inniu. Ach bhí
George W. Bush Uachtaran SAM cúig bliana ó shin. Ní dhóladh Uachtaran Bush deochanna alcólacha.
Má thug an Taoiseach dó uisce beatha, bheadh ​​scéalta grinn faoi Uachtaran Bush. Cuimhin linn go raibh
scéalta grinn go leor Bush cheana. Bheadh ​​sé bronntanas breá do Jay Leno agus David Letterman.

Cuir deireadh leis an náire a bhaineann le bronnadh seamróige (2/2)

Léigh tuilleadh

Monday Night Irish Class, April 8, 2013

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Irish Class, April 8, 2013

Rang Gaeilge, 8ú lá mí Aibreáin 2013

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Fadas: áéíóúÁÉÍÓÚ

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craiceann skin
go mall slowly
foireann staff, team
cul an tí back of the house
easna rib f4

Will was back, so we went over the first part òf the homework from last time. Corrected notes follow.

Cuir deireadh leis an náire a bhaineann le bronnadh seamróige

Léigh tuilleadh

Thomas Bayes and O.J. Simpson

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After posting about The Prosecutor’s Fallacy I recalled a similar case with the Defense in the O.J. Simpson trial. The issue was summarized in What is your favorite problem for an introduction to probability?:

… one of Simpson’s lawyers, Alan Dershowitz, noted that even though Simpson beat
his wife, that hardly mattered, because in the United States, four million women are
battered every year by their male partners, yet only one in 2,500 is ultimately
murdered by her partner (1 in 1000), so, by the ‘reasonable doubt’ criterion, this is
irrelevant. The jury found that argument persuasive, but it’s spurious. The relevant
question was what percentage of all battered women who are murdered are killed by
their abusers, which ain’t 1 in 1000, but rather 9 in 10.

For a clear explanation of the details see Chances Are, by Steven Strogatz, which is reprinted in his excellent book, The Joy of x: A Guided Tour of Math, from One to Infinity.

The Language of Space

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Want to be an Astronaut? Learn How to Speak Russian

You may wonder: “Shouldn’t Cosmonauts have to speak English?” I expect most of them learned it long before joining the space program.

In fact the situation is not symmetric. American astronauts as well as Russian Cosmonauts fly to space from a Russian-speaking site (the Baikonur Cosmodrome) in a Russian vehicle (the Soyuz).

The Prosecutor’s Fallacy

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Bayes’ Theorem … A Simple Example

Notation: Prob(A) means “the probability of event A” and Prob(A|B) is “the probability of event A, given that event B has happened.”

Bayes’ Theorem: Prob(A|B)xProb(B) = Prob(B|A)xProb(A)

Now, Prob(A|B) and Prob(B|A) are often confused by even the most intelligent of people. The confusion often appears in legal cases and is sometimes called the Prosecutor’s Fallacy. Bayes’ Theorem relates these two distinct conditional probabilities.

Followed by a straightforward example of why this really matters.