Two numbers, two people
A shop writes a phone number from a paper form into a computer.
The form says 07700 900123. The shop types 07700 900132. Two numbers swapped places. The delivery text goes to a stranger.
Nobody did it on purpose. Typing is easy to get wrong. How do we stop it?
Key words
| Word | What it means | Example |
|---|---|---|
| Data entry | Typing or choosing data to put it into a system. | Filling in a form |
| Transcription error | A mistake when copying data: a wrong, missing or extra character. | Smith typed as Smyth |
| Transposition error | Two characters next to each other swap places. | 1234 typed as 1324 |
| Validation | The system checks that a value is sensible and in the right shape. | A phone number has 11 digits. |
| Verification | The system checks that a value was typed in correctly. | Type your email twice. |
| Double entry | Typing the same data twice, and checking that both are the same. | A password box and a confirm box |
| Drop-down menu | A list of choices. You pick one, you do not type. | Year 12 or Year 13 |
| Pre-filled box | A box that already holds a likely answer. | Today's date |
The cells students fill in are left blank in this preview.
Quick check: spot the error
Have a go
Quick check: spot the error
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Transcription errors
To transcribe is to copy. A transcription error is a mistake when copying data. A character is wrong, missing, or extra.
"Smith" becomes "Smyth" (wrong). "Leeds" becomes "Lees" (missing). The number 0 and the letter O look the same, so people mix them up.
Transposition errors
A transposition error is a special mistake. Two characters next to each other swap places.
1234 becomes 1324. "form" becomes "from". The same characters are there, but in the wrong order. The person usually does not see it because the data looks right.
Examples side by side
| Correct | Typed | Type of error | Why it happens |
|---|---|---|---|
| Smith | Smyth | Transcription | Heard it, did not check |
| 07700 900123 | 07700 900132 | Transposition | Fingers went too fast |
| LS1 1AB | LS1 1A8 | Transcription | B and 8 look alike |
| Leeds | Lees | Transcription | A letter is missing |
| 2026 | 2062 | Transposition | Two digits swapped |
The cells students fill in are left blank in this preview.
Try it: find the difference
typed = "07700900132"
correct = "07700900123"
for place in range(len(typed)):
if typed[place] != correct[place]:
print("Different at place", place + 1, ":", typed[place], "should be", correct[place])
# Two places are different, and they are next to each other.
# That is a transposition. Change typed to "07700900124" and run again.
Why do people make them?
Typing is done by tired, busy people. Handwriting is hard to read. Keys are close together. Digits and letters look alike. Long numbers have no meaning, so the brain does not notice a swap.
People will always make mistakes. You can build the form to catch them.