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FeaturesSelectionsMethodologyOrdering

The data for the selections comes from the 2008-2012 American Community Survey (ACS). We have processed it so that you can easily make selections based upon the percent of people/households/housing units that meet the specified target numbers. We have taken the data for every block group in the US and created an engine to quickly make the selections of those block groups which qualify based upon the selections that you have made.

When you select zip code or city we have created a cross walk to the appropriate block groups. For every zip code that you select you are likely to be selecting all or parts of 6-10 block groups. Once the block group has been identified it then needs to be challenged to meet the selections that you requested. Once it has been selected we match it against the address count in the Willow Bend data file of addresses which covers 96% of all households and businesses in the country. So this is a way of including some parts of a zip code or city that best match your requirements without having to have the entire area meet them.

A couple of notes:

  1. If you ask for 2 or more constraints then you will drastically reduce the number of addresses that will meet your requirements. For example if you had the following sample
  2. House 1: built 1965, value 227,600
    House 2: built 1985, value 116,300
    House 3: built 1967, value 100,400
    House 4: built 1977, value 127,400
    House 5: built 1974, value 72,600
    House 6: built 1984, value 112,200
    House 7: built 1982, value 95,900
    House 8: built 1957, value 86,500
    House 9: built 1995, value 101,800
    House 10: built 1991, value 121,100

    If you ask for houses with a value over $110,000 then of the 10 you would get 5

    House 1: built 1965, value 227,600
    House 2: built 1985, value 116,300
    House 4: built 1977, value 127,400
    House 6: built 1984, value 112,200
    House 10: built 1991, value 121,100

    Similarly, if you asked for houses built since 1980 you would get 5 of the 10

    House 2: built 1985, value 116,300
    House 6: built 1984, value 112,200
    House 7: built 1982, value 95,900
    House 9: built 1995, value 101,800
    House 10: built 1991, value 121,100

    But if you asked for houses with a value over $110,000 and built since 1980 you would get only 3 of the 10 that qualify for both constraints

    House 2: built 1985, value 116,300
    House 6: built 1984, value 112,200
    House 10: built 1991, value 121,100

  3. Median versus Average
    Median means that HALF of the incidences are above and half are below. So for our houses above the median would be
  4. 227,600
    127,400
    121,100
    116,300
    112,200

    101,800
    100,400
    95,900
    86,500
    72,600

    The median would then be between 112,200 and 101,800 or 107,000

    If the top 3 values all increased by 10,000 or even 50,000 it wouldn’t affect the median at all. It would stay at the mid-point between the two middle numbers or $107,000

    On the other hand the average would be (227,600 + 116,300 + 100,400 + 127,400 + 72,600 + 112,200 + 95,900 + 86,500 + 101,800 + 121,100) / 10 = 116,180. If the top 3 values increased by 10,000 then the new average would become $119,180. If the top value was 127,600 instead of 227,600 then the median would still be $107,000 but the average would drop to $109,180.

 

        

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