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  • 1.  MapInfo Monday: Population Drive Distances

    Employee
    Posted 5 hours ago

    In last week's article, we looked at Population Circles and they describe the size of the area your locations need to serve to reach a specific population. The smaller the circle needed, the higher the population density around your locations.

    Below is an example of a map created using the instructions from that article.

    image
    Circles - or buffers, as we created last week - are just one way to illustrate population density around locations.
    Another approach is to use Drive Distance or Drive Time Regions.
    The concept is the same: You create several polygons around your locations, update each with population values, and then filter out those that match the desired population.

    Population Drive Distances

    Let's take a look at how you can do this with Drive Distance Regions. The approach would be similar for Drive Time Regions as it's just the calculation of the zones that is different.
    From the Spatial tab, click the Drive Regions control from the Regions dropdown in the Create group. This opens the Drivetime Regions window.
    In the Drivetime Regions window, select your table with locations. I select my table Sites. You must also give your Output Table a name. It will by default to using the input table name and a short name for the process type: DT for Drive Time and DD for Drive Distance.
    If the output table already exists, you can choose to overwrite it or append to it.
    As Region Name I select the ID column from the Sites table.
    I switch to Distance as calculation type, set the units to Miles and enter the first 3 distances as 1, 2 and 3 miles.
    image
    Now I click on the More Options > button.
    I set Overlapping Regions to On to make sure the regions generated will overlap each other. This is required to calculate the population within the entire drivetime region.
    I set the Complexity to 0.20 to return less complex polygons from the Drivetime service.
    And finally, I select a few more columns to include in the resulting table.
    image
    Here are the first three drive distance regions added around each of the locations.
    image
    I now process these 3 distances. When they have been calculated, I change the distance to the next three: 4, 5, and 6. I also make sure that Output Mode is now set to Append so the newly created regions are added to the existing table.
    Then I process the next set of regions. I repeat this until I have created all the distances that I want. I start with the full-mile distances and then I switch to the half-mile distances afterwards.
    image
    With all the drive distance regions created, I alter the table structure of the Sites_DD table to add an Integer column to hold the population.
    As we did last week, I use Update Column to calculate population using the proportional overlap between the drive distance regions and the block groups from the PSYTE dataset that holds the population count.
    image
    With the population assigned to each of the Drive Distance regions, I can now use the Layer Filter option to only show those regions where the population count is within my desired range. I set the range here to 40,000 to 60,000 to find a population close to 50,000.
    image
    The map below shows Drive Distance Regions with an estimated population between 40,000 and 60,000 people. The smaller the regions, the higher the population density.
    image
    Finally, we can compare Population Circles with the Population Drive Distance Regions. In practise, the differences are relatively small.
    image
    Would you prefer Drive Distance Regions over the more simple Population Circles in your own analysis?


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    Peter Horsbøll Møller
    Principal Presales Consultant | Distinguished Engineer
    Precisely | Trust in Data
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  • 2.  RE: MapInfo Monday: Population Drive Distances

    Posted an hour ago

    I certainly favour the Drivetime isochrones for humans in vehicles (not everything is).

    Depending upon the number of sites and zones created, this could take you close to the 2,000 free credits per month limit!!



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    John Ievers
    CDR Group Limited
    Hope Valley, United Kingdom
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    Original Message