Unexpected RPCs
Hi,
When looking at model data for New Jersey or for a 17-county New York - New Jersey metro area, I find some odd RPCs:
For commodity 161 (ready-mix concrete), I would expect the RPC for a metro area to be quite high, given the 90 minute shelf life of concrete. Instead, the New Jersey model has an RPC of .00048 and the 17-county metro model has an RPC of 0.000026. I could move these up manually to the supply/demand pooling figure of .56 or .41, respectively, but these still seem too low. Any hints on why the RPCs and supply/demand figures are so low?
On the other hand, when I look at sector 20 (oil and gas extraction), I find surprisingly high RPCs. If I create a model of just New York county (Manhattan), I get an RPC of .43 and a supply/demand ratio of 1.0. Presumably this is because of Manhattan's abundance of corporate headquarters rather than its geological riches, but the high RPC would seem to distort the indirect impacts of analyses that involve oil. I find similar patterns with a number of natural resource and manufacturing sectors. Any idea how to adjust these RPCs?
Thanks.
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I am guessing that the RPC for mixed concrete is that low because the target average ton-miles moved is based on more aggregated NAICs sector from the Commodity Flow Survey. I can fix that in a future data release, thanks for pointing it out. As for the oil, the corporate headquarters is supposed to be separated and placed into NAICs 55. Our data for proprietors (part of IMPLAN employment) comes from REA (formerly known as REIS) data. The BEA gets their data from the IRS, which unfortunately, is residence based. I can't imagine that there is a refinery or petrochemical manufacturing in Manhatten , so even a few resident landowners with oil producing lands would cover the demand for oil and gas extraction. In any event. If you do not have "Customize" as a menu option, go to Help>User>Preferences>Analysis (tab) and enable it with the appropriate check box. You will be editing the RSC (amount of local supply going to local demand). I suspect you will want to set oil and gas extraction to 0 and the mixed concrete to 1. -
It looks like I need to switch trade flows model to the National Trade Flows model in order to access the RSC -- is that correct? I can change ready-mix concrete's RSC to 1, but I'm curious as to whether the numerator or the denominator is off in the supply/demand ratio. It looks like demand for concrete is coming from the expected sectors (construction). For oil&gas, is the national output distributed to localities in proportion to all the value added components, including proprietor's income? Finally, is there any way to systematically detect whether RPCs are distorted by proprietor's income? I'm concerned that some manufacturing sectors may have unreasonably high RPCs in the metro region model, but I don't want to set them to 0, either, since there is actually some manufacturing here. Thanks. -
The 0's in the indirect/induced is a very old bug. Try to update the software - if Help>About IMPLAN does not show 3.0.10.2 then you probably have an original appliance with the old updater. Call in for help in updating if you don't get the latest version (a flag did not reset when you changed preferences for a model with multipliers). Several possibilities for supply/demand: 1) Output per compensation/employment ratios is higher for your 15 county region. 2) The outer ring of counties is served by nearby regions. 3) Suppliers too far away, bring in unmixed material and mix on site. Proprietor income does figure into the calculation of output, so it is possible to have output in a region that has proprietors but no production facility.
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