Combining Regions from the Region List 

INTRODUCTION

IMPLAN gives the user the ability to combine regions to allow for analysis of the Impacts beyond a single geography. However, when combining multiple regions, this process can become complicated and tedious. Fear not though IMPLAN user! This process is now streamlined with the addition of the Region List in IMPLAN V6, and combining regions has never been easier. Note you can still combine your Regions using the map as always.

DETAILS

When running an analysis in IMPLAN, a user may find it necessary to Combine Regions to assess the economic effects across a Study Area that is defined by the user. IMPLAN allows you to accomplish this with just a few clicks from the Regions screen, as seen below. Choose the Regions you wish to impact from the map, and simply hit the icon near the top right of the screen to select ‘Combine Regions’.  This will begin the process of building the Combined Region, in this example it would be a Combined Region of NC, SC, and VA using the 2019 data set. 

But what if you wanted to define a Study Area across several different counties? Or even zip-codes? Tackling this task with the method mentioned above can get sticky in a hurry. The brand new Region List option for combining Regions in IMPLAN makes this process a breeze! Access the Regions list view from the Regions screen by clicking the icon directly next to the Data Year dropdown.   

Note that you can navigate back to the Region map view by selecting the icon highlighted above. This will bring up the Region list, remember that you will have to select the Data Year that you wish to use from this page. If you select a Data Year on the Region map view, it will not follow you to the Region list view (it will reset to the default). From the Region list, you can select Regions to Combine at the State, County or Zip Code level. For example, to see all of the Counties in Alabama, highlight the state by clicking on it. We can see that doing this will bring up a list of all 67 counties in Alabama. 

If we wanted to see the Zip Codes for a certain County, say Bibb County Alabama, click it just like we did for the state of Alabama. This will bring up all 8 Zip Codes in Bibb County:

To create a Combined Region, select the non-overlapping Regions you want to include. For example, to Combine Zip Codes 35034, 35035 and 36793 we would check their boxes and press “Combine Selected Regions” at the bottom right of the screen. 

Doing this will prompt you to name your Combined Region. Make sure to choose a name that you will be able to remember, because Combined Regions can always be found/used by searching for them by title from the Region search field on both the Region and Impact screens. 

In addition to searching for a Region using the State > County > Zip Code method, you can also search for a Region by typing the name (or Zip Code) in the search bar near the top left of the screen. 

NOTE OF CAUTION

Combined Regions can be built using State, County and Zip Code level regions, this also includes US Territories, which can be Combined with other mainland US Regions. You are free to Combine any non-overlapping Regions from the list. Use discretion. You will see the following warning if you try to select a Region that is contained in another selected Region:

We received this error message because we attempted to select Fresno County with one of its parent Regions, the State of California, for a Combined Region. No matter which approach we take to Combine Regions, this will never work. This and more considerations on Combining Regions can be found in the linked support article Combining Regions. 

Also, at this time the Region list is limited to selecting 500 Regions to combine at once. At the bottom right of the screen, a running total of all the Regions you have selected is displayed. Once you have exceeded the limit of 500, the ‘Combine Selected Regions’ button will be grayed out and is unavailable to be selected. 

EXAMPLE WITH MRIO

The addition of the Regions List makes Multi-Regional Input-Output (MRIO) easier than ever before. MRIO makes it possible to track how an impact in one Region supports impacts in another Region in the US (state to state, county to county, zip code to zip code, county to multi-county, county to state, etc.) For more information on MRIO analysis, check out our support article MRIO: Introduction to Multi-Regional Input-Output Analysis. 

With the easing of COVID-19 restrictions and the increased availability of vaccinations, city officials in Charlotte, NC think that we will soon see consumers returning to public venues in droves. A conservative figure estimates an up-tick in the Output for the local Full-Service restaurant industry in the amount of $1B. 

This figure only includes the local Industry Output in Mecklenburg County. However, what if we wanted to see the effect of this increased Output in not only Mecklenburg, but the State economy as a whole? Using the Region List coupled with an MRIO analysis would be a great and quick way to tackle this. 

Now to analyze the impact across the rest of the State outside of Mecklenburg County, we need to create a new region that includes all of the other Counties in North Carolina. We could manually select all of the Counties and combine them from the map view, but using the Region List will save us a lot of time, so that is what we are going to do!

From the Region screen, switch to the list view, and select North Carolina. From the list of Counties, hit select all to quickly select all 100 NC counties, then we’ll deselect Mecklenburg.

Because we will have Mecklenburg County selected as its own Region, it should not be included in this Combined Region of the remaining counties in NC. This would produce an error running the Impact. So scroll down to Mecklenburg County and Un-check its box. We see that now we have only 99 Counties selected (out of the 100 in the state), and we can hit the blue ‘Combine Selected Regions’ button at the bottom left. Doing this will prompt you to give your Combined Region a name, remember to choose one that you can easily remember, as this new Region can be used for any future project. We’ll name ours “NorthCarolinaNoMeck” and hit save. 

After hitting save we are brought back to the Region Map view, with our new Combined Region already selected on the right. Use the search bar to also add Mecklenburg county as its own individual region, then hit ‘Create Impact’ and give your project a name.

From the Impacts screen, we are going to add a single Industry Output event for Industry 509 - Full-Service Restaurants with an Event Value of $1B. Drag and drop this Event to the Mecklenburg County Group, because this estimated increase in Output is only for Mecklenburg. Be sure to check the MRIO box at the top right of the screen so that we can see the effect across the entire state of NC. Click run. 

From the Economic Indicators by Impact table in the summary results tab, we can see the total effects of the increased full service restaurant output in Mecklenburg County on the entire state of North Carolina. 

Filtering for the Mecklenburg County Region, we can see the effects of our Impact on just Mecklenburg.

Lastly, filtering for the Combined Region of the remaining NC counties, we can see the effects of our Impact on the remainder of North Carolina outside of Mecklenburg.

RELATED ARTICLES

Combining Regions from the Map

MRIO: Introduction to Multi-Regional Input-Output Analysis

US Territories

Written May 12, 2021

Updated October 6, 2021