you are right, sentiment analysis algorithms look at a text as a bag of words (or n-grams where n is two or three), some of the tokens have been assigned some s

you are right, sentiment analysis algorithms look at a text as a bag of words (or n-grams where n is two or three), some of the tokens have been assigned some set score and the result score is a linear function based on the token counts; Changes in usage would significantly alter the result over longer time periods.