This spreadsheet has the data used to compare prices from TCAD and Zillow.
The data was from TCAD's preliminary appraisal roll for 2023. The "market_value" field holds TCAD's appraisal. The ZEstimate values were gathered on May 4th, 2023. The field "ZEstimate" holds those values.
The space was a subset of all properties. In TCAD, the property had to be real estate, had land and building type "A1" (single-family-homes) and had a single owner.
The addresses were not selected at random. I took the logartihm of TCAD's appraisal prices ("market_value") and then selected 100 values evenly distributed between the minimum and maximum value. I should have looked at the distribution first. This approach ended up with a lot of values in the bottom 1000th of the data. It would have been better to fit the log-normal distribution and then picked values based around its center.