In my use of the word "predictive", no time variable is needed (although certainly you can do predictive modeling if you do have a time variable). If you are baking chocolate chip cookies, you have temperature, you have amount of shortening, and the response is some measure of taste, you can statistically determine a relationship using temperature and amount of shortening to predict the taste.
Your sales example seems to be weak for the reasons I mentioned. It's not a statistical relationship been sales and price per unit and quantity, it's a deterministic relationship.
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