← Years 7–8 Data & Information

Judging whether collected data is essential

Data a system cannot do its purpose without. If the system could still work with it left out, the data is optional and does not need to be collected.

Part of: 7-8 Digital Technologies: Digital footprint and privacy — Module 13, ACARA Digital Technologies Years 7–8 — Acquiring and Storing Data — Module 6, ACARA Digital Technologies Years 7–8 — Digital Footprints and Data Minimisation — Module 21, ACARA Digital Technologies Years 9–10 — Privacy Principles and Digital Footprints — Module 33, QCE Digital Solutions Unit 1 — Understanding Digital Problems — Module 43

Understanding Judging whether collected data is essential in Years 7–8 Data & Information

What it does: The code shows the 'could it still work without this?' test: if the answer is yes, the data is optional. Essential data is data the system cannot do its purpose without. The app needs to know who borrowed each book, so the card number is essential. Without a username the game could not tell players apart or show them on the leaderboard, so it is essential. Giving a reason means linking the data to the purpose. Contacting a parent in an emergency is part of running a safe excursion. Ordering and delivering pizza works fine without a favourite colour, so it is optional.

Common mistakes: The test for essential data is 'could it still work without this?'. A parcel cannot be delivered without an address, so the line should say 'IF no data, cannot deliver'. As written, the test says the data is not needed, which contradicts the conclusion on line 4. A quiz game still works without your shoe size, so it is optional data. Line 3 says the game cannot be played without the data, so line 2 should name data the game really needs, such as "username".

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This module's key terms are also in a printable crossword (Modules 100–124) and word search (Modules 87–124).

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Learning
Duo
A school library app lets students borrow books. Is a student's library card number essential data?
No - the app could still work without itYes - the app can't record who borrowed a book without it
Matches
Library book app: shoe_size = essential
↓
Shoe size is not needed to borrow books. The app works without it, so it is optional and should not be collected.
Applying
Meanings
Term
essential data
Meaning
Data a system cannot do its purpose without. If the system could still work with it left out, the data is optional and does not need to be collected.
Practice
SYSTEM: school canteen app
Testing
Gaps
THEN data is
Check Answer
Spots
2data ← "delivery address"
3IF no data, can still deliver

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Quick Questions

1. A school library app lets students borrow books. Is a student's library card number essential data?
A. Yes - the app can't record who borrowed a book without it ✓
B. No - the app could still work without it
Essential data is data the system cannot do its purpose without. The app needs to know who borrowed each book, so the card number is essential.
2. A pizza shop app delivers pizzas to homes. Is the customer's favourite football team essential data?
A. Yes - the app can't deliver without it
B. No - pizzas can still be delivered without it ✓
Ask: could it still work without this? Delivery works fine without a football team, so it is optional and doesn't need to be collected.
3. Which question is the best test for judging if data is essential?
A. Could the system still work without this data? ✓
B. Would this data be interesting to have?
The test is whether the system can still do its purpose with the data left out. If it can, the data is optional.
4. An online game needs a username so players can log in and appear on the leaderboard. Is the username essential?
A. No - the game works the same without it
B. Yes - the game can't work for each player without it ✓
Without a username the game could not tell players apart or show them on the leaderboard, so it is essential.
5. A homework reminder app sends alerts to a student's phone. Which is the better reason for collecting their home address?
A. There is no good reason - reminders work without an address, so it is optional ✓
B. It is essential - every app needs an address to work
A good reason links the data to the app's purpose. Reminders don't need a home address, so it is non-essential.

Match the Pairs

Pizza app form: delivery_address (required) → Essential data: the app cannot deliver the pizza without it
Pizza app form: favourite_colour (optional) → Optional data: the app still works without it, so it does not need to be collected
The test: ask whether the system could still do its purpose if the data was left out. If it could, the data is optional. → IF works_without(data) THEN optional
Giving a reason: explain what the system could not do without the data. → email: essential because the login code is sent to it
Library book app: shoe_size = essential → Shoe size is not needed to borrow books. The app works without it, so it is optional and should not be collected.
phone_number: essential because we might want it later → 'Might be useful later' is not a good reason. Data is essential only if the system cannot do its purpose without it right now.

Key Term

essential data
Data a system cannot do its purpose without. If the system could still work with it left out, the data is optional and does not need to be collected.

Fill in the Blanks

1. IF system still works without the data THEN data is optional ELSE data is essential
Hint: Type the word for data the system does not need to work
2. Test: could it still work without this? If no, the data is essential.
Hint: Type the answer to the test question that makes data essential
3. app <- "pizza delivery" data <- "home address" essential <- true
Hint: Type the Boolean value showing a delivery app cannot work without this data
4. app <- "online maths quiz" data <- "home address" essential <- false
Hint: Type the Boolean value showing a quiz can still work without this data
5. Data: username for a game account Reason: account cannot work without it Verdict: essential
Hint: Type the word that matches the reason given in the code

Spot the Error

Question 1
A purpose ← "deliver a parcel"
B data ← "delivery address"
C IF no data, can still deliver
D THEN essential ← TRUE
Line C — The test for essential data is 'could it still work without this?'. A parcel cannot be delivered without an address, so the line should say 'IF no data, cannot deliver'. As written, the test says the data is not needed, which contradicts the conclusion on line 4.
Question 2
A purpose ← "play a quiz game"
B data ← "shoe size"
C IF no data, cannot play
D THEN essential ← TRUE
Line B — A quiz game still works without your shoe size, so it is optional data. Line 3 says the game cannot be played without the data, so line 2 should name data the game really needs, such as "username".
Question 3
A purpose ← "play music"
B data ← "email address"
C IF no data, cannot send
D THEN essential ← TRUE
Line A — The purpose does not match the rest of the program. An email address is essential for sending an email, so line 1 should be purpose ← "send an email". Playing music does not need an email address.
Question 4
A essential data: nice to have
B optional data: can be left out
C shoe size for pizza: optional
Line A — Essential data is data the system cannot do its purpose without. 'Nice to have' describes optional data. The line should read 'essential data: needed to work'.
Question 5
A data ← "pet name"
B IF app breaks without data
C THEN data is optional
D Leave it out of the form
Line B — The test should check whether the app still works without the data. If it does, the data is optional. Saying the app breaks would make the data essential, which contradicts lines 3 and 4. It should be 'IF app works without data'.

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