  One factor determining the reliability of measurements of electron
temperature using a Thomson scattering (TS) system is transmittance of the
optical bandpass filters in polychromators. We investigate the system
performance as a function of electron temperature to determine reliable range
of measurements for a given set of the optical bandpass filters. We show that
such a reliability, i.e., both bias and random errors, can be obtained by
building a forward model of the KSTAR TS system to generate synthetic TS data
with the prescribed electron temperature and density profiles. The prescribed
profiles are compared with the estimated ones to quantify both bias and random
errors.
