The parameter ranges from 3500 to 4600 , depending on the material, temperature, and individual construction for each sensor, and therefore must be determined for each thermistor.F igure 8.9 shows the variation of resistance with temperature for two common thermistor material the ordinate is the ratio of the resistance at 25. Thermistors exhibit large resistance changes with temperature in comparison to typical RTD as indicated by comparison of Figures 8.6 and 8.9. Equation 8.12 is not accurate over a wide range of temperature, unless is taken to be function of temperature; typically the value of specified by a manufacturer for a sensor is assumed to be constant over a limited temperature range.