This data comes from the Zillow Home Value Index (ZHVI), which is "a smoothed, seasonally adjusted measure of the median estimated home value across a given region and housing type." The Home Value Median can be defined as the midpoint in a frequency distribution of the market prices for all housing units sold over a period of time. The median value gives a more accurate estimation of the market price since it reflects the individual house prices and the sample size used. To obtain an annual median home value, TIA's researchers added the median home value for all twelve months and then divided by 12 months.
The Home Value Median for Detroit was not directly available in Zillow's city report. TIA researchers used the monthly records for the Detroit Metro Area to calculate the monthly median values.
The Home Value Median Ranking shows how the states' home value medians compare on a scale from 1-50, with one representing the highest home value median and 50 the lowest. For example, Illinois ranked 17th highest in 1996, but its home values declined to rank 33rd in 2018.
The Home Value Per Square Foot Median is defined by Zillow as the median value of all homes per square foot. The numeric value for the measurement is obtained by taking the estimated home value for each home in a given region and dividing it by the home's square footage.
According to Zillow, "Beginning with publication of November 2019 data, and for all subsequent releases, the ZHVI has been recomputed using a new methodology. November 2019 data is historically recalculated through 2008. A more complete time series dating to the mid-1990s will be published in 2020."
To learn more about Zillow's methodology, please refer to this article.
Data acquired from Zillow.com/data on February 3rd, 2020. Aggregated data on this page is made freely available by Zillow for non-commercial use.