Two trash bags with an arrow point down from one and another arrow pointing back up towards the other

Garbage in, garbage out

Meaning: If wrong data is put into a machine, it will produce the wrong answer.

Originated in: 🇺🇸 United States of America

Earliest attestation: William D. Mellin in The Hammond Times (1957)

This is a simple saying that is used to remind people that if you put bad data into a system, you will get bad data out of it. Computing data doesn’t improve its quality, so a mathematical result can only be as accurate as the numbers you started with. It is often used in the context of computer programming, where its used to convey that you can’t program your way out of bad data and you shouldn’t trust something just because it came from a computer. However, it can be used in any context where data is being processed, including classical mathematics, transcription, media processing, and policy-making.