Popgrid, to use _popwgt or not or when to use it?

Regarding PopGrid, i got three output files for my custom domain (Colorado 4km x 4km).
The *.cds file is a binary xml filecreated in the the first step of PopGrid’s operation.
I think i need to keep this file, but NOT to import when i am LOADING THE POPULATION INCIDENCE for colorado.
The two other files wil be loaded into BenMAP right?:
Result Population File entered on the first tab and the Result Population File with a _popwgt suffix.
These files are loaded into BenMAP on the Modify Setup window, if i am right?
I noticed in detroit setting that no such _popwgt (population growth weight file was used, why so?)

Hi Quazi,

You do not need to import the *.cds file, that’s correct. You need to import the resulting population file, but do not need to import the popwgt file.

Hi @Neal_Fann,

Isn’t it true that you need to add the _popwgt file in the ‘Load Population Dataset’ window if you need to project the PopGrid 2010 census data to a future year?

My question is - where do you specify what year you need to grow the PopGrid outputs to? For instance, I need to run an analysis using 2030 population data, but only have 2010 PopGrid outputs.

Thanks,
Kate

Hi Kate,

  1. BenMAP-CE uses that _popwgt file to allocate population counts in grid cells that straddle two or more counties or a body of water.
  2. The PopGrid program assigns 2010 census population data from the census block level to the user-specified geographic unit (e.g. 4km by 4km grid, census tract, etc). To project these counts into the future, the program assigns county-level population growth weights to each user-defined grid cell (e.g. 4km by 4km grids, census tracts, etc.). Put differently: the PopGrid program allocates the population and the BenMAP-CE program projects it into the future.

I hope this helps!

-Neal

Thanks, @Neal_Fann.

Could you elaborate more on how you project the PopGrid population (2010) to a future year (such as 2030) in BenMAP? In the ‘Load Population Dataset’ window, I have added the 2010 PopGrid population data under ‘Database’ and have checked ‘Use Population Growth Weights’ and added the _popwgt file under this checkbox (see screenshot).

LoadPopDatasetScreenshot

However, I see no place within BenMAP to specify that I want to grow the population to 2030 - can you point me to where I can do so? When I select my Population Dataset, the only year available to me is 2010.

PopnDatasetScreenshot

Should I:
(1) NOT be inputting the _popwgt file under the ‘Use Population Growth Weights’ checkbox? If yes, what goes here - user-specified growth rates (and if so, how should these be formatted?)?
(2) Be specifying the year I want to grow my population data to somewhere else within BenMAP-CE?

Thanks!
Kate

Hi Kate,

Within the “Load Population Dataset” window, you’ll see a dropdown window next to “Population Configuration.” When you selected “United States Census,” were you able to select the checkbox next to “Use Woods and Poole Population Projections”? I see it greyed out above. However, you should be able to check that box after selecting United States Census, at which point you would be able to project the US population to years from 2011 to 2050.

Hi Neal,

No - when I select “United States Census”, the checkbox next to “Use Woods and Poole Population Projections” is greyed out.

Could this be related to the fact that I am using a user-defined grid based on census blocks, rather than counties? Because of my user-defined grid, I used PopGrid to apportion census data based on age-gender-ethnicity-race as listed in the United States Census configuration.

@Neal_Fann

Also, the BenMAP-CE User’s Manual says on page 4-38:

“The Use Population Growth Weights checkbox should be checked when using population data generated by the PopGrid software application. The population weights file assists in forecasting population levels.”

So I am a little confused.

Oh, I know the problem.

You must have created a new Setup. You’re not performing this analysis in the U.S. setup, are you? The W&P projections are available only in the U.S. setup. Sorry–I should have realized this much earlier.

No worries - thanks for your help so far!

I am NOT performing this analysis in the U.S. setup. I am performing this analysis at the census block group level for a small area in Washington.

Are you saying that PopGrid is used to determine 2010 populations for a user-defined grid, but BenMAP is unable to grow the PopGrid output populations using W&P projections?

Ok–if it’s not too much trouble to do so, I’d recommend loading all of your data into the United States setup, confirming that you are able to select the Woods & Poole growth weights.

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