Public

Welcome to the CCAO Data Department's public engagement repository. Within this repository, you can:

• View public talks and other engagements with the Data Department
• View public data sets published by the CCAO
• Create a new public data request
• Contact us privately for anything not already covered here

Public Engagement

Talks

Members of the Data Department occasionally present about our work at meetups, conferences, and other events. Below are some of these events:

| Date | Title | Topics | Video | Slides | |------------|--------------------------------------------------------------------------------------------------|-------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------| | 2025/04/02 | Cook County Permit Data | permits, data engineering, open data | YouTube | PDF | | 2024/06/14 | Data science and engineering for property tax equity | data engineering, sales validation, dbt, Athena | | PDF | | 2023/09/20 | Open-Source Property Assessment: Using Tidymodels to Help Allocate $16B of Annual Property Taxes | R, data science, predictive modeling, property taxes | YouTube | PPTX | | 2023/01/17 | Why Are Chicago Property Taxes So High? (And What Can Be Done to Lower Them?) | R, public finance, TIF, property taxes | YouTube | PPTX | | 2022/08/16 | Cook County Assessor's Residential Model V3 | data science, predictive modeling, R, Tidymodels | YouTube | PPTX | | 2021/01/20 | Cook County Assessor's Residential Model V2 | data science, predictive modeling, R, Tidymodels | YouTube | PPTX | | 2019/04/18 | Cook County Assessor's First Chi Hack Night | predictive modeling, R, government, public finance | YouTube | |

AMAs

The Data Department has also done a reddit AMA, where we answered questions about the office and modeling.

| Date | Title | Topics | Link | |------------|------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------|------------------------------------------------------------------------------------------------------------| | 2022/06/08 | We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! | public finance, property taxes, assessments, government | reddit |

Open Data

The Data Department creates and public assessment-related data sets on the Cook County Open Data Portal. You can find a full list of the published data sets using the cook county assessor search tag.

For a broad overview and description of the data we publish, see the 2023 Open Data Refresh story on the data portal.

To learn more about our standards for publishing and maintaining open data, see the Open Data SOP on our wiki.

Data Requests

If you're looking for assessment data, but don't see what you need in Open Data, then you are welcome to create a public bulk data request. This repository leverages public issue templates to manage such requests. Please read the documentation below before making a request.

We strive to meet a turnaround time of 14 business days. However, operational priorities come before public data requests. We will communicate with requesters if we cannot meet our turnaround target.

Is this a Freedom of Information Act Request?

No. This repository is a service offered by the Data Department and does not supersede the Freedom of Information Act. A data request submitted via this repository is not a request that falls under the Freedom of Information Act.

In order to file an official FOIA request, please visit our site. Departmental discretion governs this request mechanism.

What types of requests do we process?

Transparency can be costly, and our department has limited resources. We process requests for bulk data. We do not process requests for data analysis, including graphs, sophisticated tabulations or matching, time-consuming data cleansing, etc.

We will limit our expenditure on repeated data requests from the same requester if we believe the repetition is due to 'scope creep'. This often happens when the requester does not have a sufficiently clear understanding of the data they want, and uses our department to help refine their ideas. We do not have the resources to help refine your research question.

If you have a specific project and need data from our office, we're happy to help. If we choose not to process a request, we will clearly indicate our rationale on the issue ticket.

Process for making a request using GitHub

1. Check to see whether your data is available on the Cook County Open Data Portal.
2. Check to see whether someone has already requested the data you need by looking through prior requests.
3. Open an issue ticket for your data request. You click here to create a new request using the correct template. Follow the instructions in the template to complete your request.

When your issue is submitted, GitHub will notify Data Department staff. Your issue will be assigned and tracked.

Data delivery

When ready, your data will be saved on our public S3 bucket and a link will be shared in the issue comments. Your data will be saved with the issue ticket number in its name, e.g. 17-data-request.csv. Your data will remain on S3 for one month - you should download it as soon as possible.

If you specified in your issue that you would like the data delivered as a new Open Data assets, then we will share a link in the issue comments once your asset is ready.

Contact Us

If you have a question or issue that is not covered by the content of this repository, then please reach out via email. Our department email address is Assessor.Data@cookcountyil.gov.

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