We have developed a metallized ceramic open-ended probe for dielectric properties' measurement. We have also been using finite-difference time-domain (FDTD) numerical simulations to aid in the calculation of the dielectric properties of thin samples from open-ended probe measurements. We have extended the FDTD simulations to aid in quantifying an error analysis in the measurement procedure using the open-ended probe method. The analysis has been used to quantify the errors induced into the measurement procedure by (a) differential thermal expansion between the inner and outer conductor, (b) air gaps between the sample under test and the probe, and (c) due to measurements on rough surfaces. In this paper, the measurement and calculation procedures are summarized and results from the error analysis are presented.