Maxima, Minima, and Mixtures – Probably Overthinking It


I’m exhausting at work on the second version of Suppose Bayes, presently engaged on Chapter 6, which is about computing distributions of minima, maxima and mixtures of different distributions.

Of all of the adjustments within the second version, I’m notably happy with the workouts. I current three new workouts from Chapter 6 beneath. If you wish to work on them, you need to use this notebook, which incorporates the fabric you will want from the chapter and a few code to get you began.

Train 1

Henri Poincaré was a French mathematician who taught on the Sorbonne round 1900. The next anecdote about him might be fabricated, but it surely makes an attention-grabbing likelihood downside.

Supposedly Poincaré suspected that his native bakery was promoting loaves of bread that had been lighter than the marketed weight of 1 kg, so daily for a 12 months he purchased a loaf of bread, introduced it residence and weighed it. On the finish of the 12 months, he plotted the distribution of his measurements and confirmed that it match a standard distribution with imply 950 g and customary deviation 50 g. He introduced this proof to the bread police, who gave the baker a warning.

For the subsequent 12 months, Poincaré continued the follow of weighing his bread daily. On the finish of the 12 months, he discovered that the typical weight was 1000 g, simply accurately, however once more he complained to the bread police, and this time they fined the baker.

Why? As a result of the form of the distribution was uneven. In contrast to the traditional distribution, it was skewed to the best, which is in step with the speculation that the baker was nonetheless making 950 g loaves, however intentionally giving Poincaré the heavier ones.

To see whether or not this anecdote is believable, let’s suppose that when the baker sees Poincaré coming, he hefts n loaves of bread and offers Poincaré the heaviest one. What number of loaves would the baker need to heft to make the typical of the utmost 1000 g?

Train 2

Two medical doctors contemporary out of medical faculty are arguing about whose hospital delivers extra infants. The primary physician says, “I’ve been at Hospital A for 2 weeks, and already we’ve had a day once we delivered 20 infants.”

The second physician says, “I’ve solely been at Hospital B for one week, however already there’s been a 19-baby day.”

Which hospital do you suppose delivers extra infants on common? You possibly can assume that the variety of infants born in a day is effectively modeled by a Poisson distribution.

Train 3

Suppose I drive the identical route 3 times and the quickest of the three makes an attempt takes eight minutes.

There are two site visitors lights on the route. As I strategy every mild, there’s a 40% likelihood that it’s inexperienced; in that case, it causes no delay. And there’s a 60% likelihood it’s pink; in that case it causes a delay that’s uniformly distributed from zero to 60 seconds.

What’s the posterior distribution of the time it will take to drive the route with no delays?

The answer to this train is similar to a method I developed for estimating the minimal time for a packet of information to journey by way of a path within the web.

Once more, here’s the notebook where you can work on these exercises. I’ll publish options later this week.


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