This is the scariest page on the site! For some factors, as high a score as possible is desirable (e.g. School achievement), while for others as low as possible is desirable (e.g. Crime rate), whereas for still others, a range is desirable (e.g. Median Age). We refer to these three possibilities as three types of algorithms. We allow users to choose an algorithm type for each factor.
For “As High As Possible” and “As Low As Possible” algorithms we ask users to define an “Acceptable Region”. This is the range of factor values that the user finds acceptable, and where a change in the value makes a significant difference. For instance, for the school achievement index, it could make sense to set the “Acceptable Region” from 60 to 80. Once this “Acceptable Region” is defined we automatically define an “Unacceptable Region” and a “Region of diminishing returns”. In the example above the “Unacceptable Region” would be set from 0 to 60 and the “Region of diminishing returns” from 80 to 100. “Unacceptable” means that the user is strongly predisposed against a value in that range. “Diminishing returns” means that once a score goes above a certain value, increasing it any more does not make that much difference to the user.
Note that even though the “Acceptable” region is where most of the action is, we do not completely eliminate communities which are slightly in the unacceptable range.
The Range algorithm is similar to the other two. There is no “Diminishing Returns” region, but there is a “Preferred Region”. Scores which are in the preferred region will receive maximum values. The preferred region should be within the acceptable region.
Once these 2 ranges are specified, the “Unacceptable region” is automatically determined. As an example, median house price might be a factor for which the Range algorithm is appropriate. A user might decide that an ideal value would be between 300,000 and 350,000, and set that as the “Preferred Region”. Furthermore, the user may decide that plus or minus 50,000 more, is still acceptable, although not quite as satisfactory. The Acceptable Region will then be set from 250,000 to 400,000.
The overall score is the weighted combination of the scores for each factor.