The following steps are used to score and grade metro areas in each sub-category.
- For each indicator a common procedure is used to normalize the values. For this, the mean value across all metro areas is subtracted from the original values. Then the result is divided by the standard deviation of the original values distribution.
- To obtain scores for a specific sub-category, all normalized indicators in that sub-category are summed up and then divided by the standard deviation of the resulting sum. Thus, each sub-category score’s distribution is normalized as well (has zero mean and standard deviation equal to one).
Note that at this step the summation is done with equal weights.
- Letter grades from A+ to F are assigned based on the sub-category score using the following table:
The following steps are used to grade metro areas in each of the three “E” categories.
- To obtain scores for one of the “E” categories, a similar to a sub-category procedure is followed. All standardized indicators in that category are summed up with equal weight by default. Thus, the indicators that participate in two sub-categories are not counted twice. Then the sum is divided by its standard deviation to yield normalized final scores.
** Optionally, the weights of sub-categories can be modified in the visualizations. In this case, all normalized indicators in a sub-category will have the selected weight. For categories participating in two sub-categories, there is a weight sharing: the corresponding term in the sum will be equal to 0.5 x sub-category-1-weight + 0.5 x sub-category-2-weight.
- Letter grades from A+ to F are assigned according to the table above.