Reading temperature

I am trying to record temperature using a thermistor but I am getting a 5°C fluctuation for a non varying set temperature.
I have used a 10K Ohm Resistor, would changing this value help?
This is how I have set it up

Choose R near NTCs R (raw reading ca 500 in room temp)

Sorry for being a bit thick but what does NTC stand for?

Negativ Temperatur Coefficient
You will find equations to calculate actual temp..

Whats printed on that component .. / datasheet ?

be sure that you have a stable power supply, some vary up to 5%
You can check that with a DMM (Digital MultiMeter)