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modifying the RSC

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BECAnalyst
Hello, I've been having some trouble modifying the RSC in the Trade Flows --> Trade Model window for my multi-county region. The pattern seems to be that I can only adjust RSC upward for sectors in which local demand exceeds local supply, not for sectors in which local supply exceeds local demand. Note that I am not trying to increase RSC to 100% in these cases as that would be impossible; I'm simply trying to increase RSC to the point where local use of local supply = local supply. When I do this, save changes and then rebuild the model, my changes to the RSC do not stick, but rather revert to their original values. On the other side, I've noticed that in the Trade Flows --> Industry/Institution RPC window, I can adjust the RPC upward (e.g. to 100%) for commodities which have local supply exceeding local demand, but not for industries where local demand exceeds local supply. Why is this the case? I feel like I should be able to adjust RPC and RSC upwards up until the point where local use of local supply = local supply, as long as local use of local supply does not exceed local supply, regardless of whether local demand exceeds or is less than local supply. Thanks for your time!
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  • Avatar
    BECAnalyst
    My version of IMPLAN is up to date.
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    DougO
    The RSC is the ratio of local demand going to local supply. If local demand exceeds local supply, then the RSC can be pushed to 100%. Conversely, if supply exceeds demand only a portion of the supply can go to demand - ie, the max RSC = Demand/Supply. The RPC works a bit differently, it is the ratio of local demand met by local supply. The max RPC = Supply/Demand.
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    BECAnalyst
    Right. But IMPLAN won't let me increase RSC *at all* when supply exceeds demand. I talked to one of your technicians on Friday and she didn't know what was going on either. Also, when is it appropriate to use institutional spending changes vs. industry changes? If I model an institutional spending change, e.g., the construction of a public facility, am I assuming that the government diverting money from other projects it funds and putting it towards this new facility instead?
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    DougO
    V3 is letting me push up the RSC (when it doesn't hit a constraint). In the edit trade flows window - the "Local Use of Local Supply" element can not exceed either the "Local Net Commodity Supply" element (no more supply exists) nor the "Local Gross Commodity Demand" element (there is no more local demand for that supply). Only use the "industry/Institution RPC" when you are looking at the local purchase of a commodity by a specific industry or institution.
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    BECAnalyst
    What constraint might the RSC be hitting? (I tried pushing it up in v3 and so did Frances from the IMPLAN office and we both encountered this issue.) Also, when is it appropriate to use institutional spending changes vs. industry changes? If I model an institutional spending change, e.g., the construction of a public facility, am I assuming that the government is diverting money from other projects it funds and putting it towards this new facility instead?
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    DougO
    Which data files, for which year? Which commodity and what value were you trying to push the RSC to?
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    BECAnalyst
    IMPLAN v3 2008 County Totals El Dorado + Placer + Sacramento + Sutter + Yolo + Yuba for Vegetables and Melons I want to change the RSC from 58.860% to 74% for Fruit I want to change the RSC from to 35.441% to 59% Thanks!
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  • Avatar
    DougO
    I have (for vegetables and melons) Local Gross Commodity Demand = 215,999,600 Local Net Commodity Supply = 290,019,600 The RSC constraint = Demand/Supply = 74.47758 The software will allow me to set it to 74.477% but not 75%. I suspect a similar problem for fruit. We may have slightly different numbers as I have developmental data.
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  • Avatar
    BECAnalyst
    i have the same numbers for Local Gross Commodity Demand and Local Net Commodity Supply but when i build the model initially the default RSC for vegetables and melons is 58.860%. i changed the RSC to 74.477%, saved changes and then rebuilt the model through Options --> Construct --> Multipliers. once the model was done building, i returned to the Trade Flows window and saw that the RSC for vegetable and melons was 58.860% again! i brought this problem to Frances last week and she was able to replicate the problem. how else can i troubleshoot this?
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    DougO
    I talked to Frances about this last night. I was under the impression from your posts that the software simply didn't let you modify. But apparently, it's that the modification doesn't "stick" once you leave the customizing screen. It is a bug - I think that the either the commodity supplies or commodity demands are not being calculated correctly for display in the customizing screen - and the ~58% is the actual constraint. We'll let you know as soon as there is an update. Thanks for bringing it to our attention.
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