When you woRk, you probably have a set of useful functions/packages you constantly use. For example, I often use the excellent quantmod package, and the nice multi.sapply function. You want your tools loaded when R session fires.

# Category: Miscellaneous

## Elegant backup for your smart phone contacts

Few days ago I dropped my iPhone and cracked it. Though the iPhone still works, I decided it will be good to have a backup for my contact on my desktop. Fancy backup can be achieved in the following two step procedure: first synching your contacts information with facebook, and second, sending yourself an excel file with full details of your mobile contacts, phone number, date of birth, home page, work address and other details extracted from their facebook page. The process takes only few minutes and is free.

## Behavioral Economics in action

Do doctors unnecessarily prolong Colonoscopy? the answer is: they surely might.

## Random books

It seems like a very long while since my bachelor. Checking my bookshelf the other day I was thinking to flag some of those books which helped or inspired me along the way. Here they are in no particular order.

## Marriage is good for your income

For those of you who are into machine learning, here you can find a cool collection of databases to play around with your favorite algorithm. I choose one out of the available 200 and fit a logistic regression model. The idea is to see what kind of properties are common for those who earn above 50K a year. Our data is such that the “y” variable is binary. A value of 1 is given if the individual earns above 50K and 0 if below. We know many things about the individual. Level of education in years, age, is she married, where from, which sector is she working in, how many working hours per week, race, and more. We can fit logistic regression, which is quite standard for a binary dependent variable, and see which variables are important.

## U.S. prison population

I recently finished reading: The author writes that 6.6% of U.S. American residents will find themselves at some point in their life incarcerated, about 20 million people. A big number on anyone’s scale. You can also find disturbing figures in Wikipedia: figure. Are these facts misleading? we need to account for population growth. The prison population should naturally rise even if the proportion of crime in the general population is constant, since the population itself is growing. Here I show that these facts are NOT misleading, and that the system is indeed not fulfilling its purpose.

## Do they really know what they are doing?

I am talking here about money managers. for those of us who have one. We assume they understand about markets in such a way that they can, and will generate at least the benchmark returns, what ever this benchmark may be.

## Flash Crash

In his book, “A demon of our design”: Richard Bookstaber talks about the concept of coupled systems. These are systems where, once launched, are impossible to shut down. One such process is a plain take off. Once started, the pilot has no way back, he cannot stop after getting off the ground, so the only way is up. Well, in financial markets, up is generally considered good,

## When to avoid traffic if possible

At some point I was thinking that there must be some data available out there on car accidents. With some free time on my hands I downloaded few numbers from the Central Bureau of Statistics in Israel, which has basically any road accident statistics you can think of. (in Israel)