Does Location Really Matter? New Assessor’s Office Tool Shows the Sales and Data That Have the Most Impact on Your Home’s Value

The Cook County Assessor’s Office released a new tool that gives Cook County homeowners unprecedented insight into the data that drives a home’s assessment.

The Home Value Report is available now at www.cookcountyassessoril.gov/home-value-report.

It shows homeowners the top five most significant sales and other details the CCAO’s residential assessment model used to value their house.

These other details include physical characteristics like square footage and age, as well as location features like school district, distance to transit, airport noise, and flood risk score.

Every year, the Assessor’s Office reassesses one-third of Cook County. To do this for residential properties, the Assessor’s Data team develops a statistical model. This is a computer program that uses vast amounts of data to learn real estate trends.

These trends are used to estimate current property values. The team refines the model so that its results accurately, uniformly, and equitably follow the market.

The Home Value Report provides accessible information about how the model reached its estimates.

“With this release, we’re making it easy to understand how our industry-leading model valued your home. This represents a milestone in our ongoing effort to make Cook County’s property tax system fully transparent to all residents,” said Cook County Assessor Fritz Kaegi.

 

The Home Value Report currently contains data for the 2024 reassessment of Chicago and the 2025 reassessment of the north suburbs.

“As we reassess the southern and western suburbs next year, we’ll add data for those homes as well. Each year, residents will see how recent sales affected their assessment,” said Assessor Kaegi.
 

Why the Assessor’s Office built the Home Value Report

The Assessor’s Office regularly releases valuation reports that shows how residential assessments changed by township, as well as data on property sales.

However, there was no tool that was both specific and accessible enough to quickly give homeowners the information they wanted. The model’s code and documentation are public, but this repository still requires a sophisticated understanding of data science, machine learning, and programming.

To fill this gap, the Data team created an algorithm to retrieve the inputs that most substantially drove the estimated value for a home. They used this to build the Home Value Report. The benefits of this accessible, web-based tool are the following.

• Specific to an individual home
• Easy to use and filter information
• Includes a scoring system to show which data matters the most
• Features an interactive map and neighborhood-level statistics about properties

The Home Value Report includes information about property characteristics, identifying which features of a home and its comparable properties contributed the most to the model’s estimated assessment. It also features an interactive map and neighborhood-level statistics about properties.

A more detailed explanation of the model and the algorithm used to build the Home Value Report is available here: https://ccao-data.github.io/lightsnip/articles/finding-comps.html

The Home Value Report is available here: https://www.cookcountyassessoril.gov/home-valuereport