Unemployment and market clearing

In a recent blog post, Karl Smith defends U3 from it's critics. The majority of his defense is spot on - U3 is a consistent, well-understood measurement which we can use to measure changes over time, and we also have a pretty good understanding of it's relationship to other relevant quantities …

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A High Frequency Trader's Apology, Pt 1

I'm a former high frequency trader. And following the tradition of G.H. Hardy, I feel the need to make an apology for my former profession. Not an apology in the sense of a request for forgiveness of wrongs performed, but merely an intellectual justification of a field which is …

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In-app caching - spend a little RAM to speed up your site

HTTP is a stateless protocol. For this reason, it's often considered bad practice to store data in your server's memory the memory of your webserver to be a bad practice. In general, this is correct - your webserver's ram is a bad place to store permanent data. It's volatile, and if …

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One Hiring Filter that Works

In a fairly popular blog post, Raganwald advocates against using various heuristics while filtering out resumes. For the most part, I agree with him. Since it's hard to find good programmers, false negatives are very costly compared to the cost of a false positive (a wasted interview).

But I have …

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How to leave academia

So you've decided to leave academia, or are perhaps just thinking about doing so. Welcome to the dark side. I made the transition a few years ago, and since then I've gotten a number of questions about how to do it. Hence, this article.

First of all, I'm going to …

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Introducing Hobo

In this post I'd like to introduce Hobo, a fast in-memory index for your data. Hobo is not a database, it's an external index for data you have stored elsewhere. Hobo is used for two primary purposes - the first is to answer queries of the form "find me all items …

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A simple trick to speed up complex Postgres queries on EC2

A major problem with running Postgres on EC2 is that EBS performance often sucks. In addition to performing poorly, EBS also uses the network connection, which can be undesirable. Ephemeral storage is provided, and tends to have better performance characteristics, but unfortunately it lacks durability.

However, we can still use …

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Networking problems while cloning Ubuntu VM

I've run into a curious error while cloning Ubuntu VM hard drives. After cloning, the network card no longer works. However, if I clone the VM completely (including the mac address), there is no problem. The reason for this is that Ubuntu, upon installation, stores the mac address of the …

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