The Illinois Association of REALTORS® (IAR) has discovered a technical error related to inconsistent data reporting that has resulted in inaccurate median price and sales volume reports for single-family homes and condominiums specifically and solely for the city of Chicago. This unintentional technical error only relates to city of Chicago housing data; county and statewide reports were not affected by the error and remain accurate. (Source: http://www.illinoisrealtor.org/IARhousingdata)
This could cause some concerns with economists and speculators who closely watch for housing trends or plan their investments based on changes in the marketplace.
The error could be caused by how the formula in excel was calculated, although there is no specifics. The monthly data that I provide here is pulled directly from MRED, the local MLS (multiple listing service) and compiled locally through MRED, and provided that the actual information in the MLS was accurate to begin with, data here with regards to median housing values, months supply of inventory and supply & demand should not contain the same errors.