What's the simplest way to calibrate a thermistor?
Reading Thermistor is a little tricky. 
The above method of calibration, wield no yield to an error detection, It would create two points of a logarithmic curve (the thermistor response curve. 

This means, for every 0.1°C of changue of temperature, the correspondent changue on resistance will vary, depending on the range of the temperature. 


At first, you might look an error about 2 to 5°C off the real temperature, yet no error, only a bad reading. 

You dont post any details on how are you reading this thermistor, Arduino May be? 
I must say, some libraries dont work at all, so you must create a especial function to do so. 

Post on detailed explanation on how to characterize and read an thermistor.
The post is in spanish, but in the code tags, all explanation in in plain English.

Once you have obtain you ABC coeficients, your error will be about 0.1°C from another measurement, even in a 6m long run of LAN wire.


This test read at the same time the 4 thermistors, You can see a small difference in temperature from 2 of them I was holding briefly in my fingers.