Name: Size Doesn’t Matter: How Two Assessors’ Offices Built It Themselves
Start: 2027-02-25T09:00:00-0800
End: 2027-02-25T10:30:00-0800

Size Doesn’t Matter: How Two Assessors’ Offices Built It Themselves

Thursday February 25, 2027 9:00am - 10:30am PST

Daisy, 2nd Floor

Skagit County, WA: a non-developer built and shipped a free suite of browser-based tools — sales ratio analysis, exemption screening used across all 39 counties, a levy trends visualizer — each a single HTML file, no backend, no procurement. AI-assisted development got it built; discipline is what made it trustworthy — validated against certified output, root-caused on real data, defensible at a Board of Equalization hearing.

Maricopa County, AZ: a Comparable Sales tool from 2009 had held appraisers together for two decades. Going remote forced a rebuild, so the team modernized it with open-source tools — Python, Shiny, Leaflet, SQLite.

Different tools, same lesson: you don't need a developer, a budget, or a procurement cycle. Just the right approach — and the discipline to trust what you ship.

From Assessor to Builder: Shipping Free, Audit-Ready Tools Without a Developer
Keywords: Workflow Automation & Custom Tools, Artificial Intelligence & Machine Learning, Intermediate
Danny Hagen, Assessor, Skagit County, Washington

Modernizing the Computator: Revamping an Open-Source Comparable Sales Tool
Keywords: Workflow Automation & Custom Tools, GIS & Spatial Analysis, Mass Appraisal & Valuation Modeling, Beginner
Autumn Mittemiller, Data Scientist, Maricopa County (Arizona) Assessor’s Office
Leroy Johnson, AAS, Data Scientist, Maricopa County (Arizona) Assessor’s Office

Speakers

Danny Hagen

Assessor, Skagit County

As Skagit County Assessor, Danny Hagen brings a technology-forward approach to public service, using data, systems, and collaborative problem-solving to drive fairer, more transparent government.

Danny serves as President of the Washington State Association of County Assessors (WSACA) and 2nd Vice President of the Washington Association of County Officials (WACO) Board of Trustees, where he works to foster collaboration and innovation across Washington's county governments... Read More →

Autumn Mittemiller

Data Scientist, Maricopa County Assessor’s Office

Autumn Mittemiller has worked for the Maricopa County Assessors Office for 5 years as a data scientist within the CAMA unit. During her time with the county, she has become known for her innovative mindset and creating diverse tools using open sourced software for her team.

Leroy Johnson, AAS

Data Scientist, Maricopa County

Leroy joined the Maricopa County Assessor’s Office in 2013 as an appraiser, then joined the CAMA team in 2020 as a Regression Modeler now a Data Scientist. Leroy is a member of the IAAO and earned his A.A.S designation. Working with CAMA Leroy has developed skills in SPSS, Python... Read More →

Thursday February 25, 2027 9:00am - 10:30am PST
Daisy, 2nd Floor

Data Technology and Analytics

GIS/ValTech 2027

Danny Hagen

Autumn Mittemiller

Leroy Johnson, AAS

Attendees (1)

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GIS/ValTech 2027

Danny Hagen

Autumn Mittemiller

Leroy Johnson, AAS

Attendees (1)

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