← VCE Data Analytics U3O1

Justifying functions, formats and conventions

Give a reason for a design choice (chart, colour, format) that links it to the purpose of the solution, the needs of the audience and the type of data. Use 'because' to link them.

Part of: VCE Data Analytics - U3O1 - Data Analytics — Module 128

Understanding Justifying functions, formats and conventions in VCE Data Analytics U3O1

What it does: The reason names the audience and their situation, which is what linking to the audience means. The reason refers to the data type (time series) and the purpose (trend), so the choice is justified. The justification links the colour choice to the audience's needs. Red and green are hard to tell apart for many colour-blind people. Software features are not a reason linked to the audience. The better answer ties the choice to who will read it. The colour is justified by the audience (managers) and the purpose (quick spotting of problems), not by personal taste. A justification must link to the purpose, audience or data, for example: pie chart, because it shows parts of a whole for 4 categories.

Common mistakes: A line chart is justified because the data is ordered over time. The data line should describe time-based data, such as sales for each month, not categories. A pie chart shows parts of a whole, which matches share-of-votes data. Showing change over time is a job for a line chart, so the reason should be 'parts of a whole'.

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This module's key terms are also in a printable crossword (Modules 94–128) and word search (Modules 94–148).

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Learning
Duo
Which is a justification for using a line chart to show monthly rainfall over a year?
A line chart is the best because it looks nicer than the other charts.A line chart suits this data because it is a time series and the line shows the trend from month to month.
Matches
I used a pie chart because it looks nice.
↓
The reason is only personal opinion. It does not link to the purpose, audience or data type.
Applying
Meanings
Term
Justify a design choice
Meaning
Give a reason for a design choice (chart, colour, format) that links it to the purpose of the solution, the needs of the audience and the type of data. Use 'because' to link them.
Practice
Choice: line chart for monthly rainfall
Testing
Gaps
Line chart the data is time-based.
Check Answer
Spots
1Choice: line chart
2Data: sales split by category

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Quick Questions

1. Which is a justification for using a line chart to show monthly rainfall over a year?
A. A line chart is the best because it looks nicer than the other charts.
B. A line chart suits this data because it is a time series and the line shows the trend from month to month. ✓
A justification links the choice to the type of data and the purpose. 'Looks nicer' is an opinion and gives no link to the data.
2. A dashboard is for busy school leaders who need a quick overview. Which justification links the design to the audience?
A. I used large headline numbers because the leaders have little time and need the key result at a glance. ✓
B. I used large headline numbers because I like big text.
A good justification names the audience and their need. Personal preference is not a reason linked to the audience.
3. Which justification for choosing a pie chart is stronger?
A. A pie chart suits this data because it shows how 4 categories make up parts of a whole 100%. ✓
B. A pie chart suits this data because pie charts are popular.
The strong answer links the chart to the data type (parts of a whole). Popularity is not linked to the data or purpose.
4. Which sentence correctly uses 'because' to justify a colour choice in a chart for colour-blind readers?
A. I used blue and orange because they are easy to tell apart for people with colour vision deficiency. ✓
B. I used red and green because they are bright colours.
The justification links the colour choice to the audience's needs. Red and green are hard to tell apart for many colour-blind people.
5. Which statement is a justification of a design choice, not just a description?
A. I used a scatter graph with blue dots and a title.
B. I used a scatter graph because the purpose is to show the relationship between two numeric variables. ✓
A description says what was done. A justification says why, linking the choice to purpose, audience or data.

Match the Pairs

Column chart, because it compares totals across categories → A justification that links the chart choice to the purpose (comparison) and the type of data (categories)
Red for low stock, because managers need to spot problems quickly → A justification that links a colour choice to the audience's needs and the purpose of the visualisation
Justifying a format by linking it to the audience: the reason must refer to who will read it → Large 18pt font, because Year 7 students will view this on a classroom projector
Justifying a chart by linking it to the type of data: the reason must say what kind of data is shown → Line chart, because the data is time series and the purpose is to show a trend over months
I used a pie chart because it looks nice. → The reason is only personal opinion. It does not link to the purpose, audience or data type.
I chose blue and green because they are my favourite colours. → The reason is personal preference and does not mention the audience, purpose or data.

Key Term

Justify a design choice
Give a reason for a design choice (chart, colour, format) that links it to the purpose of the solution, the needs of the audience and the type of data. Use 'because' to link them.

Fill in the Blanks

1. Line chart because the data is time-based.
Hint: Type the linking word that connects a design choice to its reason.
2. Bar chart because the data is categorical.
Hint: Type the data type used for labelled groups that are being compared.
3. Large text because the audience is Year 7.
Hint: Type the word for the people who will read or use the solution.
4. Dashboard because the purpose is to monitor.
Hint: Type the word for what the solution is meant to achieve.
5. Choice: scatter graph Reason: both fields are numeric data.
Hint: Type the data type shared by both fields being compared.

Spot the Error

Question 1
A Choice: line chart
B Data: sales split by category
C Purpose: show trend over time
D Reason: it suits time data
Line B — A line chart is justified because the data is ordered over time. The data line should describe time-based data, such as sales for each month, not categories.
Question 2
A Choice: pie chart
B Data: share of votes by party
C Audience: Year 7 students
D Reason: shows change over time
Line D — A pie chart shows parts of a whole, which matches share-of-votes data. Showing change over time is a job for a line chart, so the reason should be 'parts of a whole'.
Question 3
A Choice: dark blue text
B Background: white
C Reason: it looks nice
D Audience: readers of a report
Line C — A justification must link to the purpose, audience or data using 'because'. 'It looks nice' is only an opinion. It should say something like 'high contrast to read'.
Question 4
A Choice: large 24pt headings
B Used in: a wall poster
C Reason: posters are read close
Line C — Large headings are justified because a wall poster is read from a distance. Saying posters are read up close contradicts the choice and the context. It should say readable from afar.
Question 5
A Choice: scatter graph
B Data: names of 5 teams
C Purpose: show a relationship
D Reason: plots pairs of values
Line B — A scatter graph is justified by data with two numeric variables. Team names are text categories and cannot be plotted as pairs, so the data line should say two numeric variables.

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