Progress!
After a couple of days of correcting data issues and consequently learning a few new tricks with PostGIS that will come in handy in the long run, I am pleased to announce that this evening I ran my first simplified test regression with my data for 1970. I chose a random SIC code (15–), which turns out to be contract construction. Unsurprisingly, employment in contract construction goes up where there is higher population density, a higher proportion of people with college degrees, and higher median earnings (i.e., productivity). And, gratifyingly, employment goes down the further you get from a port or an intermodal terminal. And all values had highly significant coefficients.
So I can finally see a light flickering at the end of the tunnel. I’ve got to load in census data from 1980, 1990, and 2000, and that will surely require a bunch of fiddling around. But I’ve developed some vim strategies for creating my SQL scripts and I’m optimistic that the data will be cleaner and more straightforward than the 1970 data.
Two additional notes for researchers. First, despite my hurry to get done, I’m putting in extra time this time to put together a GIS-enabled database of census data, County Business Patterns data, and other sources and to put it together right (i.e., with notation, reliable corrections, etc.). This way, I should never have to go searching for this data again (or, at worst, will have a frame to plug it into). This has required expending time expanding my coding skills, but this, too, should pay long term dividends.
The second note is about the delight that is the processed NHGIS data. I’m still having some issues with the projection, which I think is NAD83 North Carolina (ESRG 2264) (for my future reference!), but the data is wonderful, GIS-coded, and easy to use. For a person with basic GIS abilities, they would be able to easily plot historic maps using QGIS or a similar program.
And let me just add finally that the entire project is being done open source and that pleases me to no end.
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