Lesson 5 of 8
Examples from one place
Show on a big screenThe early bus brings six crates. All are fresh. What will the board miss?
Fresh means 3 days old or less. Older means 5 days or more.
Step 1 of 4
- Six bus crates, all fresh. Small dots are kept-back test crates.
- Fresh test crates: 5 of 5 right.
- Older test crates: only 2 of 5 right.
- The lorry brings 4 older crates. Older crates: 5 of 5 right.
It will get many older crates wrong. It has seen none.
The rule
A place is a part of the board, like the fresh part. Examples from one place teach one place. Add examples from the missing places.
Data with places left out has data bias. A program taught from it guesses worse for what is left out. This can happen by accident.
| Crates on the board | Fresh right | Older right |
|---|---|---|
| Bus only (6) | 5 of 5 | 2 of 5 |
| Bus and 3 more bus crates (9) | 5 of 5 | 2 of 5 |
| Bus and lorry (10) | 5 of 5 | 5 of 5 |
A program never shown an older crate has nothing to copy.
Flip a switch. Watch the older crates.
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Try the lab to finish this lesson.