Publications by Adam.Hyland
Stationarity
In time series work you often run into difficulties in modeling processes where the overall level of one variable (an input, for example) changes over time but the levels of another variable (an output) do not change. For instance if you want to use primary school enrollment as a factor in economic growth for a cross country regression over time...
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Bootstrapping the Truncated Normal Distribution
Here’s a post generated from my own ignorance of statistics (as opposed to just being marred by it)! In Labor Economics we walked through something called the truncated normal distribution. Truncated distributions come up a lot in the sciences because you may have some sample from a large population which is normall distributed but the sample...
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Our Friend the Age-Earnings Profile
I like Labor Economics. Partially because it has a nice mix of theory and practical empiricism, but mostly because it seems to be a sub-field with a number of agreed upon stylized facts that grow not out of micro theory but out of hundreds of empirical studies. One of those facts is the age-earnings profile [PDF]. Basically, as individuals age...
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A Short Return to the Age-Earnings Profile
Two posts ago I mentioned the age-earnings profile but did not provide a regression of log earnings on wage. I also offered, without evidence, that fitting a simple linear regression would be inappropriate. How do I know that? How could we determine the appropriateness of a regression? There are a number of technical or econometric means to d...
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I’m late for π day
It is officially no longer pi day, but I didn’t see this Drew Conway post about estimating pi until just a few minutes ago. Because Google Reader doesn’t show github embeds, I also got to try it without seeing Drew’s solution. The estimation method relies on exploiting the area of a circle. We can use R to generate random numbers for our...
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More pi plus 1 (or plus 0.01) day fun
Since I just didn’t get enough this morning, I spent some more time fooling around with estimating pi. Since I was basically counting the number of random x,y pairs inside a quarter circle and computing a sample average for more and more iterations I wondered how sensitive my results were to small or large sample sizes within each iteration. ...
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No simulation is complete without a gif
I promise this is my last post on the now week and a half old π pay! Building on the last post, I figured I could show how convergence actually works in the estimation algorithm. If you’ll recall, we plotted a number of x,y pairs inside a square inscribing a quarter circle. The ratio of those points inside the quarter circle to the overall ...
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Radiation levels at Fukushima
From BWR The above graph is derived from data scraped from TEPCO press releases. Every hour or so for the first few days of the crisis, a TEPCO van would record radiation (probably Beta/Gamma, but the translation is unclear) at the front gate to the Fukushima complex. The series is less continuous than the graph would lead you to believe, but ...
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A Simple Instrumental Variables Problem
When working with labor economics, we often run into issues with selection on variables of interest. Regressing earnings on years of education to estimate the human capital earnings function makes sense at first blush until we imagine that education is not randomly assigned–your equation is capturing the selection on education and the effects ...
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Measuring Price Dispersion of Marijuana
The intersection of mapping APIs, fast database operations and user engagement offers a lot of very cool crowdsourcing applications ranging from the benign and powerful (Google’s Person Finder) to the minor and questionable (A DUI checkpoints app). Most intriguing in this mix of applications and websites are the unexpected. Clay Shirky spends...
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