Actuarial Outpost Marid Audran
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## Found a job outside the industry

Posted 04-29-2009 at 04:24 PM by Marid Audran

Looking back on it, it seems that my studies took a huge hit the moment I started on my second job, a temporary part-time gig. Then, right when that ended, I landed myself a full-time position at a different place altogether. I've withdrawn from Exam MFE (will get at least some of my registration \$ back, at least) for this spring...may take it in the future, just for kicks.

Good luck to all, particularly those who are studying for their exams.
Posted in Miscellany

## If A,B,C are independent, then AnB (resp., AuB) and C are independent

Posted 02-02-2009 at 01:12 AM by Marid Audran

(Using n for intersection and u for union, since the built-in TeX is terrible with those symbols.)

Oddly enough, Rosenthal's probability book doesn't seem to even point this out, and my other probability book (Hogg/Craig, from several years back) doesn't see fit to prove it or make a big deal of it. I think it's a big deal. If I've got it right, then I think the proof helps explain why "independence" is defined as a distinct phenomenon from "pairwise independence."*...

## Probability theory textbook: Secret weapon or red herring?

Posted 02-01-2009 at 12:33 AM by Marid Audran

As interesting as the Rosenthal probability text is to me, I wonder whether I'm doing myself a disservice by spending much time on it. My hope is that I'll better understand the underlying theory (e.g., measure theory) and thus be better equipped to do challenging exam problems (not to mention being more ready to actually use probability in the workplace). But it's clear that others have tried to understand the deeper theory too and mostly found it unnecessary (see, for example, this thread on Ito's...

## Note to self: Read "Qualifications" list in job postings from the bottom upward

Posted 01-28-2009 at 09:27 AM by Marid Audran

Doing so would help me judge lists like this one* more quickly:
• Detail-oriented
• High school diploma
• Self-starter
• Able to communicate with others, both verbally and in writing
• MS Excel, intermediate-level or higher
• Able to type 40 WPM or greater on a computer keyboard
• Work as an individual and as part of a team
• Twelve or more years of industry experience
• Fellowship in the Society of Actuaries
Grrr! I can imagine, barely, why hiring managers might want to do it this way: FSA's...
Posted in Miscellany

## Divergence of the harmonic series, in a probability context

Posted 01-27-2009 at 10:42 PM by Marid Audran
Updated 02-06-2009 at 11:54 PM by Marid Audran (Adding a remark that it's not obvious)

I thought of this while reading in Rosenthal's book about the Borel-Cantelli lemma and trying to think up an example.

I learned a long time ago that the harmonic series
$\sum_{n=1}^\infty \frac 1n$
diverges to infinity. Nonetheless, when I thought of the following example (which boils down to this fact), it felt less than completely intuitive to me.

Consider an infinite sequence of real numbers $x_1, x_2, x_3, ...$, where each number is chosen randomly from the interval $(0,1)$...