Reliability measure of price indices

#1
Is there any method to calculate a reliability score for a price based on the date gap?

As an example if the price has not varied over a large period of time that means the std deviation of that price is low then the reliability of that price is not varying is high.

On the other hand if the price has changed drastically that means the std deviation of that price is very high then the reliability of that price is not varying is low.