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Urban Start-up Agglomeration and Venture Capital Investment (view source)
Revision as of 15:30, 16 November 2020
, 15:30, 16 November 2020no edit summary
=New Work=
===Heuristic Layer===
[[File:AgglomerationInflectionScatterPlotAllData.png|300px|right]] I had previously calculated the heuristic layer by calculating the mean fracinhull (i.e., % of startups in economic clusters) for each percentage of the layer index (i.e., for 101 observations) and then fitting a cubic to it. I did this because excel can't handle fitting a cubic to the full data (i.e., all 148,556 city-year-layers). However, it is incorrect - I should have used the median fracinhull, and even that would have been slightly wrong because of orthogonality issues. So I redid the plot using all the data, and calculated the cubic in STATA instead. See: '''inflection.do''' and '''inflection.log'''.
The old result is in [https://www.edegan.com/wiki/Urban_Start-up_Agglomeration_and_Venture_Capital_Investment#Fixing_an_issue Fixing an issue] below, and is x≈0.483879. The corrected result is x≈0.487717 (note that R2 has dropped to 92.43%):
:2.737323 x^3 - 4.005114 x^2 + 0.3262405 x + 0.9575088≈0.481497 at x≈0.487717 [https://www.wolframalpha.com/input/?i=inflection+points+2.737323+x3+-+4.005114x2++%2B+0.3262405x+%2B+0.9575088]
===Another list of items===
