Generalising an exact value into a range

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. A survey stores each student's exact birth date. Which change is an example of generalising?

A Replace the birth date 14/03/2011 with the age band 12-13

B Replace the birth date 14/03/2011 with the student's name

2. What is the main reason for generalising an exact value into a range?

A It makes the data more exact so people can be found easily

B It makes the data less identifying but still useful

3. Which is a generalised version of the exact address '12 Wattle St, Brunswick'?

A Brunswick

B 12 Wattle St

4. A dataset lists exact incomes like $52,310. Which column is better for privacy?

A Income: $52,310

B Income band: $50,000-$59,999

5. You are studying which year levels use the school library. Which age grouping suits this question?

A Bands that match year levels, like 12-13 and 14-15

B One band for everyone, like 10-18

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1=IF(B2<13,"Under 13","13 and over")		ABands that are only 1 year wide are almost as exact as the real age, so they still identify people. Use wider bands such as 10-12, 13-15 and 16-18.
2=LEFT(C2,4)		BTurns an exact age into a broad age band so the exact number is no longer stored
3Generalising an exact income into an income band so the exact amount is hidden		C=IF(D2<50000,"Under 50k","50k or more")
4Generalising a full street address into just the suburb		DKeeps only the first 4 characters of a value, such as a postcode, so it points to a wider area
5=IF(B2<13,B2,"13 and over")		E="Suburb: "&B2
6Age bands: 1 year, 1 year, 1 year		FThe formula still returns the exact age for younger people, so it does not generalise those values. Both outcomes should be bands, such as "Under 13".

Definitions

generalising

Fill in the Blanks

Complete each line of code by filling in the missing parts.

=__(B2<13,"Under 13","13 and over")

=IF(B2_13,"Under 13","13 and over")

=____(C2,2)

IF income < 50000 ____ band ← "Under 50k" ENDIF

=IF(B2<13,"Child",__(B2<18,"Teen","Adult"))

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A birthDate ← "2011-05-14"

B age ← 14

C band ← "13 to 15"

D OUTPUT birthDate

Question 2

A street ← "12 Oak St"

B suburb ← "Hawthorn"

C shared ← street

D OUTPUT shared

Question 3

A income ← 62000

B band ← "$62,000"

C OUTPUT band

Question 4

A IF age < 16 THEN

B band ← "Under 16"

C ELSE

D band ← "Under 16"

Question 5

A ageBand ← 14

B rowID ← "P07"

C OUTPUT rowID, ageBand

Answer Key

Generalising an exact value into a range

Section A: Quick Questions

A — Replace the birth date 14/03/2011 with the age band 12-13

B — It makes the data less identifying but still useful

A — Brunswick

B — Income band: $50,000-$59,999

A — Bands that match year levels, like 12-13 and 14-15

Section B: Match the Pairs

=IF(B2<13,"Under 13","13 and over") → Turns an exact age into a broad age band so the exact number is no longer stored

=LEFT(C2,4) → Keeps only the first 4 characters of a value, such as a postcode, so it points to a wider area

Generalising an exact income into an income band so the exact amount is hidden → =IF(D2<50000,"Under 50k","50k or more")

Generalising a full street address into just the suburb → ="Suburb: "&B2

=IF(B2<13,B2,"13 and over") → The formula still returns the exact age for younger people, so it does not generalise those values. Both outcomes should be bands, such as "Under 13".

Age bands: 1 year, 1 year, 1 year → Bands that are only 1 year wide are almost as exact as the real age, so they still identify people. Use wider bands such as 10-12, 13-15 and 16-18.

Section C: Definitions

generalising — Replacing an exact value with a broader group, like a birth date with an age band, so the data is less identifying but still useful.

Section D: Fill in the Blanks

=IF(B2<13,"Under 13","13 and over")

=LEFT(C2,2)

IF income < 50000 THEN
  band ← "Under 50k"
ENDIF

=IF(B2<13,"Child",IF(B2<18,"Teen","Adult"))

Section E: Spot the Error

D — The program should share the age band, not the exact birth date. Outputting birthDate keeps the identifying value. It should be OUTPUT band.

C — Generalising an address means sharing only the broader suburb. Sharing the street keeps the exact address. It should be shared ← suburb.

B — An income band is a range, not the exact income. "$62,000" is still the exact value. It should be a range like "$50,000 to $79,999".

D — Both groups were given the same label, so the data can no longer tell the groups apart. The ELSE branch should be band ← "16 and over".

A — The ageBand variable should hold a range such as "13 to 15". Storing 14 keeps the exact age, so nothing has been generalised.