Confirming charts and graphs represent the data

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. A column chart shows Maths = 80, but the source table says Maths = 88. What should you do?

A Fix the chart so the plotted value matches the source data (88)

B Leave it, because the chart looks about right

2. Which check confirms a chart uses the correct categories?

A Compare each category label on the chart with the labels in the source data

B Check that the chart uses bright colours

3. A column chart's vertical axis starts at 50 instead of 0. What is the risk?

A The plotted values change in the source data

B Differences between columns look bigger than they really are

4. A source table has 8 students, but the chart shows only 7 columns. What does this show?

A The chart does not fully represent the data, so a category is missing

B The chart is fine, because 7 columns is close enough

5. Pie chart slices should add up to which total?

A Any total, as long as the slices are different sizes

B 100% of the source data's total

Match the Pairs

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

Left column		Right column
1=SUM(B2:B9)		ACounts how many source rows belong to one category so it can be compared with that chart bar or slice
2=COUNTIF(B2:B9,"Tech")		BThe chart range leaves out the last row, so a category is missing and the totals are wrong. Extend the range to B9.
3Check that the chart's total matches the total in the source data		CAdds the source values so the total can be compared with the total shown on the chart
4Check that a plotted value matches the source cell it came from		D=SUM(C2:C9)
5Column chart of marks with the y-axis starting at 45 instead of 0		EThe axis does not start at zero, so small differences look huge and the bars do not show the data in proportion. Reset the axis minimum to 0.
6Chart series range =Sheet1!$B$2:$B$8 when the data runs to row 9		F=B4

Definitions

Chart verification

Fill in the Blanks

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

=__(B2=F2,"Match","Check")

=IF(___(B2:B9)<=100,"Axis fits","Rescale")

=______(A2:A9)

=IF(SUM(B2:B9)_F2,"OK","Wrong total")

=IF(___(B2:B9)>=0,"Axis from 0","Check")

Spot the Error

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

Question 1

A source ← [12, 18, 9, 21]

B chart ← [12, 18, 9, 21]

C totalSrc ← SUM(source)

D totalChart ← SUM(source)

E IF totalSrc = totalChart THEN

F OUTPUT "Totals match"

Question 2

A barChart ← TRUE

B axisMin ← 20

C IF axisMin < 0 THEN

D OUTPUT "Bars exaggerated"

Question 3

A srcCats ← ["Mon","Tue","Thu"]

B chCats ← ["Mon","Tue","Wed"]

C IF srcCats = chCats THEN

D OUTPUT "Categories match"

Question 4

A total ← 100

B shares ← [40, 25, 35]

C FOR EACH s IN shares

D total ← total + s

E IF total ≠ 100 THEN

F OUTPUT "Fix pie"

Question 5

A src ← [30, 45, 60]

B plotted ← [30, 54, 60]

C IF src = plotted THEN

D OUTPUT "Values match"

Answer Key

Confirming charts and graphs represent the data

Section A: Quick Questions

A — Fix the chart so the plotted value matches the source data (88)

A — Compare each category label on the chart with the labels in the source data

B — Differences between columns look bigger than they really are

A — The chart does not fully represent the data, so a category is missing

B — 100% of the source data's total

Section B: Match the Pairs

=SUM(B2:B9) → Adds the source values so the total can be compared with the total shown on the chart

=COUNTIF(B2:B9,"Tech") → Counts how many source rows belong to one category so it can be compared with that chart bar or slice

Check that the chart's total matches the total in the source data → =SUM(C2:C9)

Check that a plotted value matches the source cell it came from → =B4

Column chart of marks with the y-axis starting at 45 instead of 0 → The axis does not start at zero, so small differences look huge and the bars do not show the data in proportion. Reset the axis minimum to 0.

Chart series range =Sheet1!$B$2:$B$8 when the data runs to row 9 → The chart range leaves out the last row, so a category is missing and the totals are wrong. Extend the range to B9.

Section C: Definitions

Chart verification — Comparing a chart's plotted values, category labels, totals and axis scale with the source data to confirm the chart shows the data accurately.

Section D: Fill in the Blanks

=IF(B2=F2,"Match","Check")

=IF(MAX(B2:B9)<=100,"Axis fits","Rescale")

=COUNTA(A2:A9)

=IF(SUM(B2:B9)=F2,"OK","Wrong total")

=IF(MIN(B2:B9)>=0,"Axis from 0","Check")

Section E: Spot the Error

D — The chart total must be calculated from the plotted chart values. Using SUM(source) compares the source with itself, so it can never find a difference. It should be totalChart ← SUM(chart).

C — A bar chart axis that starts above 0 exaggerates differences between bars, so the warning must appear when axisMin > 0. Using < 0 would never warn for a truncated axis. It should be IF axisMin > 0 THEN.

A — The source categories should be Mon, Tue and Wed. Thu does not match the chart's Wed label, so the check would report a mismatch even though the chart is correct. Line 1 should list "Wed" as the third category.

A — A running total must start at 0. Starting at 100 would make the pie slices add up to 200 and give the wrong check. It should be total ← 0.

B — The plotted values should be the same as the source values. The 45 has been swapped to 54, which is a typical transposition error. It should be plotted ← [30, 45, 60].