A positive influx of new residents to a community indicates that a city is thriving enough to attract new residents. Attracting national talent to Louisville will strengthen our local economy. Additionally, growing our regional and cultural diversity with new residents will enrich the vibrancy of our communities.
Louisville currently ranks 8th among its peers in net migration flow with a net migration flow of 356 residents in 2015. In addition to Louisville, only seven of its peer cities had a positive net migration rate in 2013. Net migration flow is established through ACS survey data, which tracks whether respondents have lived in the same residence as one year ago and, if not, the location of their previous residence.
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.
Louisville’s net migration flow has been decreasing since it peaked in 2010 at approximately 9,000 new residents. Despite the steady decline since 2010, Louisville’s net migration flow remains positive and greater than its peer city average. Since 2011, Louisville’s peer city average has been approximately zero.
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.
