You can be very productive writing poems but how do you measure your productivity? Number of lines you write per day? Similarly in software development it is c

You can be very productive writing poems but how do you measure your productivity? Number of lines you write per day? Similarly in software development it is commonly understood that the lines-of-code is a bad metric for productivity. Some people write many lines while others may eliminate lines from it. In general "productivity" is about economic activity and thus measured in monetary terms. But that doesn't make it any simpler.