Anomaly between two series

[ivanokeeffe]

Hi guys,
Not sure where else to ask this question, but does anybody know the best way to determine an anomaly between two series?
For example, if two thermometers are supposed to read the same data:
thermometer1 : [10 10 20 20 30 30]
thermometer2: [10 10 20 20 30 30]
But over time thermometer 2 becomes inaccurate:
thermometer1: [10 10 20 20 30 30]
thermometer2: [10 10 20 25 35 40]

Does anybody know how you could pick up something such as this?
Thanks for helping a guy out!

[ivanokeeffe]

@tailaiw Hoping you might be able to help :)

[tailaiw]

I think RegressionAD should work.