← VCE Data Analytics U3O1

Checking an AI-generated visualisation against the data

Compare every value, label and axis scale in an AI-generated chart with the original data, and look for invented figures, before you trust or use the chart.

Part of: VCE Data Analytics - U3O1 - Data Analytics — Module 133

Understanding Checking an AI-generated visualisation against the data in VCE Data Analytics U3O1

What it does: AI can add or make up categories and values that are not in the source data, so every category must be traced back to a row. 540 is not a rounded 450. The digits have been changed, so the chart does not match the data and must be fixed. The AI may repeat its error or invent a reassurance. The source data is the reliable reference to check against. AI tools may pick an axis range that makes small gaps look huge, so the scale must be checked before use.

Common mistakes: The check is reversed. Using == flags values that match. To catch chart values that differ from the source data, it should be !=. The loop variable is day, not days, so the check fails with a NameError. It should compare ai[day] with src[day] for each source value.

Class: _____________________  ·  Name: _____________________  ·  Date: _________

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This module's key terms are also in a printable crossword (Modules 130–148) and word search (Modules 94–148).

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Learning
Duo
An AI tool gives you a bar chart of your sales data. What should you do before using it?
Compare each bar's value with the source dataTrust it because AI tools are always accurate
Matches
The chart looks professional, so I will submit it without opening the dataset.
↓
A polished look does not prove accuracy; the chart was never compared with the source values, labels and axes.
Applying
Meanings
Term
Check against source data
Meaning
Compare every value, label and axis scale in an AI-generated chart with the original data, and look for invented figures, before you trust or use the chart.
Practice
=IF(ROUND(AVERAGE(B2:B9),1)=72.4,"Matches","Check")
Testing
Gaps
=(B2:B9)
Check Answer
Spots
3for i in range(len(source)):
4 if source[i] == chart[i]:

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Quick Questions

1. An AI tool gives you a bar chart of your sales data. What should you do before using it?
A. Trust it because AI tools are always accurate
B. Compare each bar's value with the source data ✓
AI can misread or change data, so every value must be checked against the original source before you use the chart.
2. The source data shows Term 3 sales of 450, but the AI chart labels that bar as 540. What does this show?
A. A harmless rounding difference
B. A value error that must be corrected ✓
540 is not a rounded 450. The digits have been changed, so the chart does not match the data and must be fixed.
3. An AI line chart has a y-axis that starts at 90 instead of 0, which makes a small rise look huge. What should you check?
A. The axis scale, to see if it exaggerates the change ✓
B. Only the chart colours
A truncated or odd axis scale can mislead the viewer. Check that the scale fairly represents the source data.
4. Your data has 5 months, but the AI chart shows 6 columns including a month called 'Aug' that is not in your file. What is this?
A. Invented data that should be removed ✓
B. Extra detail that improves the chart
AI can make up categories or values that do not exist in the source. Any figure not in the data must be removed.
5. Which check is part of confirming an AI-generated chart is accurate?
A. Check that labels and titles match the source data fields ✓
B. Check that the chart looks professional
A good-looking chart can still be wrong. Labels, values and axes must match the original data.

Match the Pairs

Chart bar for Term 3 = 52, source cell C4 = 25 → Compare with source values: a value on the chart does not match the source data, so it must be corrected
Y-axis starts at 90 instead of 0 on a column chart → Check the axis scale: a truncated axis exaggerates small differences between bars
Look for invented data: the AI chart shows a category that is not in the dataset → Chart has a 'Sept' bar but the CSV only has Jan to Aug
Compare the total of the chart values with the total of the source data → =SUM(B2:B9) - SUM(chart_values) should equal 0
The chart looks professional, so I will submit it without opening the dataset. → A polished look does not prove accuracy; the chart was never compared with the source values, labels and axes.
Source data is in dollars but the AI chart axis label says 'Units sold' → The label does not match the source data, so the chart is misleading and the label must be corrected.

Key Term

Check against source data
Compare every value, label and axis scale in an AI-generated chart with the original data, and look for invented figures, before you trust or use the chart.

Fill in the Blanks

1. =SUM(B2:B9)
Hint: Type the function that adds the source values, so you can compare the total with the one shown on the AI chart.
2. =MAX(B2:B9)
Hint: Type the function that finds the largest source value, so you can check the chart's axis scale reaches it.
3. =COUNT(B2:B9)
Hint: Type the function that counts the numbers in the source data, to check the chart has no invented extra bars.
4. =IF(B2=F2,"Match","Check")
Hint: Type the comparison operator that tests whether the source value is equal to the chart value.
5. =MIN(B2:B9)
Hint: Type the function that finds the smallest source value, to check where the chart's axis starts.

Spot the Error

Question 1
A source = [12, 18, 25, 30]
B chart = [12, 18, 25, 30]
C for i in range(len(source)):
D if source[i] == chart[i]:
E print("Mismatch", i)
Line D — The check is reversed. Using == flags values that match. To catch chart values that differ from the source data, it should be !=.
Question 2
A src = {"Mon": 5, "Tue": 8}
B ai = {"Mon": 5, "Tue": 8}
C for day in src:
D if ai[days] != src[days]:
E print("Check", day)
Line D — The loop variable is day, not days, so the check fails with a NameError. It should compare ai[day] with src[day] for each source value.
Question 3
A values = [40, 55, 90]
B axis_start == 0
C if axis_start > 0:
D print("Axis starts above 0")
Line B — A single = is needed to store the axis start in a variable. Using == only compares and leaves axis_start undefined, so the axis scale check cannot run.
Question 4
A src = ["Ava", "Liam", "Mia"]
B chart = ["Ava", "Liam", "Zed"]
C for name in src:
D if name not in src:
E print("Invented:", name)
Line C — To look for invented data, loop over the chart's labels and test each one against the source. Looping over src can never find a name that exists only in the chart.
Question 5
A src_title = "Sales by Month"
B chart_title = "Sales by Month"
C if src_title != chart_title
D print("Label differs")
Line C — The if statement is missing its colon at the end. It should be if src_title != chart_title: so the label check runs.

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