Researchers have found that as cities become more dense, economic opportunity increases and people spend smaller percentages of their income on housing and transportation. Additionally, residents in less sprawling cities tend to be safer, healthier, and live longer than residents in cities that are more sprawling. By retaining more of our city’s population in Jefferson County, we can ensure that Louisville is a competitive city in the future.
Louisville currently ranks 7th among its peers in percent of the population living in the core metropolitan statistical area (MSA) county, with 59.8% of the population of Louisville’s MSA living in Jefferson County, Kentucky. According to the U.S. Census Bureau, a metropolitan statistical area is a core area with a substantial population nucleus together with surrounding communities that have a high level of economic and social integration with that core.
Louisville is in the middle tier of its peer group according to a natural breaks algorithm. Cities in green are those that outperform their peers, cities in yellow represent the middle cluster, and those in red are a group that lags behind its peers on this indicator.
The percent of Louisville’s MSA population has remained nearly constant since 2010. Louisville’s near constant rate has been consistently higher than its peer city average.
For each indicator, Greater Louisville Project assigns cities into one of three groups (high-performing, middle-of-the-pack, and low-performing) based on how they compare to other cities. The assignment is based on how cities naturally cluster on that indicator. Sometimes, the differences between cities are very small, and the difference between a city ranked 5th and 6th could simply be a matter of the sampling error that arises from using survey data. Thus, rather than always make a division that declares the top 5 to be the top tier, we use a natural breaks algorithm to look for a cluster of cities that is outperforming the rest, a cluster that is about average, and a cluster that is lagging. This clustering gives us a better indication of where Louisville is thriving and where Louisville has room to learn from cities that are doing better.
Z-scores (or standardization) is a way to combine data with different units of measurement into a single index. The z-score is a measure of how far away a city (or census tract, etc.) is from the average city. In order to be comparable across different units of measurement, the z-score is the distance from the mean measured in standard deviations (e.g. if Louisville has a z-score of 1 it means Louisville is 1 standard deviation above the mean of its peer cities).
Data from the Robert Wood Johnson Foundation's County Health Rankings use z-scores and all z-scores are relative to the mean of Louisville's peer cities. (On the County Health Rankings site z-scores are relative to all the counties in each state - thus z-scores reported by GLP will be different, because we are using a different reference group). The Greater Louisville Project also uses z-scores in our multidimensional poverty index, which compares each census tract to the mean of all census tracts in Louisville.
