No. 287 · Evidence · Systems
Garbage In Garbage Out
No system, however clever, can produce better answers than the information it is given.
In the Almanac
“Babbage and the wrong figures”, 1864 · “Mizuho Securities”, 2005
Both stories in full, three ways to use it and where it misleads.
Get the AlmanacQuestions
What is Garbage In Garbage Out?
Garbage In Garbage Out means the quality of any output is capped by the quality of its input. A flawless machine fed wrong figures still gives wrong answers, often wrapped in convincing precision.
How do you use Garbage In Garbage Out?
To use it, question the source before the analysis, curate what you feed your mind, and read back critical numbers before you hit confirm. You won't always have perfect inputs, so know how good yours are and hold your conclusions with matching confidence.
When does Garbage In Garbage Out matter?
Garbage In Garbage Out is one of the 68 mental models for evidence, the situations where you ask: Is this really true? Within that, it belongs to “Where information comes from”, alongside Bias from Incentives, Echo Chambers and Filter Bubble.
What is an example of Garbage In Garbage Out?
Two stories show it at work: Babbage and the wrong figures (1864) and Mizuho Securities (2005). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.
Which mental models are related to Garbage In Garbage Out?
Unforced Error, Algorithms and Selection Bias. Garbage In Garbage Out itself comes from systems.