There are many other sources of error too, and could compute the 3 sigma variation with your algorithm , noise, drift and voltage reference error then add them up.

Design Improvements.

- calibration is essential
- You could also use 2 or 4 in a bridge method.
- if you had a constant current source, you could measure conductance with a linear output
- Using excel, if it is repeatable, you can compute higher order exponentials and correct errors in an Arduino. (When CV19 became global in March 2019, I used an 11th order polynomial with John Hopkins data to predict the curves 6 months out with high accuracy.)
- You may have mechanical hysteresis problems, which depends on many factors.
- read about tolerance-stackup calculations then decide if you want high confidence 6 sigma or std confidence 2 or 3 sigma for error probability