Induced Impacts and Commute Patterns

tbanda

March 30, 2013 02:18

[b]To what extent are commute patterns applied in IMPLAN in the estimation of induced impacts?[/b] On several occasions, where the County of analysis has a high proportion of in-commuting workers, I have adjusted the induced impact results to account for the fact that the majority of worker expenditures are not likely to be in the same county. [b]So I'd like to confirm whether such adjustment is necessary at all, or whether IMPLAN already fully accounts for the fact that for certain counties, the direct and indirect workers may largely be in-commuters and so their spending impacts will largely be generated elsewhere. Also, if commute patterns are incorporated, are they applied uniformly for the entire county or differentiated for different industries?[/b] I'm running impacts for a construction project in San Francisco (City/county), and commute data from US Census shows that construction workers have higher rates of in-commuting than the average work force.

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IMPLAN Support
March 30, 2013 04:08

Hello Tepa, There is a single regional commuting flow that is used in the Model. It reflects the overall net commuting rate for a region. Whether or not you will adjust the full amount of the value of commuting income from you entered Employee Compensation and Proprietor Income will depend on what, if any, in-commuting is tracked in you area. The place you will go to see this in each Model is the Explore>Social Accounts>IXC Social Accounting Matrix. If payment are made from the Employee Compensation and Proprietor Income columns to the 28001 Domestic Trade row, then you have net in-commuting and then you will want to reduce the amount of compensation that you remove from Labor Income to account for what the Model is removing. For example: If you knew that commuting for your industry impact was 10% and you determined the model was removing 2%, you would only want to adjust for 8% in you entered value. The [url=http://implan.com/V4/index.php?option=com_kunena&func=view&catid=80&id=15010&Itemid=35#15019]following post[/url] provides this information: [quote]To determine what amount to decrease Employee Compensation by, you can use the following equation: newEC = EC*[(1-userCR)/(1-samCR)] where: EC = original, unmodified employee compensation userCR = your known commuting rate samCR = commuting rate reported in the SAM newEC = the EC value you want to use when running the analysis So, for example, if the SAM shows that the average commuting rate in your region is 10% but you know that for your industry it is 20%, then: newEC = $1,000,000*(0.8/0.9) = $1,000,000*(0.88888) = $888,888 After the scenario has been run, add the difference (EC - newEC) back to your direct EC effect since by definition EC occurs at the site of employment. This way, you correctly account for the in-commuters' direct effect, but you have made sure that they did not generate any further local impact. You may also want to add a little income back in to account for anticipated expenses that non-local workers may have in the region, such as hotels and restaurant spending.[/quote] If no value is reported in that column:row (5001:28001) then your region has net out-commuting, and you can remove your full value directly unless you want to account for some spending while in the region.

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