Talking with Obama supporters

They say that at social gatherings one should avoid politics and religion to avoid disharmony. But this rule is frequently broken when people feel that they are with like-minded people where they can say things without fear of being contradicted. My social circle consists of self-described liberals who are all Obama and Democratic party supporters. They are people who view themselves as politically conscious and they raise issues of politics all the time and, at least in the US, politics is closely intertwined with religion, so that supposedly taboo topic comes up too.

During the period leading up to the elections of 2008, these social gatherings were pretty much a love fest, with all of us hoping that Obama would win and [Read more…]

The haves and have-soons

John Hodgman of The Daily Show tells the 99% to be patient, that soon they too will be in the 1%.

To get suggestions on how to view clips on The Daily Show and The Colbert Report outside the US, please see this earlier post. This clip appeared on February 2, 2012.

The answer is 17

I think that most people are familiar with Sudoku puzzles. There are some interesting questions that can be asked such as what is the minimum number of the 81 boxes in the grid that need to be filled in initially (the ‘clues’) in order to be able to obtain a unique solution?

It is known that for at least some puzzles one can obtain a unique solution with 17 clues, and no one had found any puzzles with 16 clues that had unique solutions. But is 17 the minimum number required? If you [Read more…]

Why randomness doesn’t always look random

I got the lightning puzzle that I posed yesterday from the latest book by Steven Pinker The Better Angels of Our Nature: Why Violence Has Declined that I reviewed in December. He uses it to illustrate that our intuitive notions of randomness and probability can easily lead us astray.

Here is the problem again.

Suppose you live in a place that has a constant chance of being struck by lightning at any time throughout the year. Suppose that the strikes are random: every day the chance of a strike is the same, and the rate works out to one strike a month. Your house is hit by lightning today, Monday. What is the most likely day for the next bolt to strike your house?

Here is his answer followed by [Read more…]

When is lightning most likely to strike again?

Since I have been taking about probabilities recently, here is a little puzzle for people to ponder overnight.

Suppose you live in a place that has a constant chance of being struck by lightning at any time through the year. Suppose that the strikes are random: every day the chance of a strike is the same, and the rate works out to one strike a month. Your house is hit by lightning today, Monday. What is the most likely day for the next bolt to strike your house?

Feel free to post your answers in the comments. I will give the answer tomorrow along with a discussion.

Blogs with homework. Now there’s a novel concept!

Update: The solution and discussion are posted here.

Probabilities and false positives

In response to my post on random drug testing in Florida, commenter Scott mentioned the danger of false positives and said that a second test in his case cleared him of having taken drugs. My advice to anyone is that whenever you take a high-stakes test for anything that has a small incidence in the general population (drugs, diseases, whatever) and it comes out positive, always consider asking for a second test.

Here’s why. [Read more…]