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Reading & WritingChapter 3: Command of Evidence

Notes

Interpreting Bar Graphs Notes

Compare categorical values and grouped series without losing labels, scale, or units.

Practice this topic
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About 28 minutes
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Bar graphs make comparisons across categories visible. On the SAT, those comparisons become evidence for a supplied point; the tallest bar is relevant only when the claim actually concerns the maximum.

What the SAT is testing

Command of Evidence
A supplied claim or point is evaluated with the textual or quantitative evidence that best supports, illustrates, weakens, or challenges it.

Core concept

Read the title, category axis, numeric axis, scale, units, and legend. For grouped bars, identify both the category and the series before reading a height.

Evidence distinctions

Category

The group along the category axis. Example: Site A

Series

The measure or condition represented by bar style. Example: Before vs after

Comparison

The evidence relationship. Example: After exceeds before only at Site C

Step-by-step strategy

Claim-first evidence method

  1. Identify

    State the exact claim, including its population, condition, direction, and qualification.

  2. Predict

    Ask what evidence would look like if the claim were true—or what would challenge it.

  3. Locate

    Select only the text or data relevant to that predicted relationship.

  4. Compare

    Evaluate direction, scope, directness, and required assumptions across choices.

  5. Verify

    Check the chosen wording and every cited value against the stimulus.

Visual and data-reading strategy

Workshop attendance by locationGrouped bars compare synthetic attendance before and after evening sessions.
  • Before
  • After
Workshop attendance by location0255075100NorthCentralSouthConditionAttendees (people)
View chart data
SeriesConditionAttendees
BeforeNorth42
BeforeCentral51
BeforeSouth39
AfterNorth58
AfterCentral54
AfterSouth63

Worked example

Worked example

Apply 3-5

A grouped graph shows workshop attendance before and after evening sessions were added. North: 42/58; Central: 51/54; South: 39/63.

Question: Which evidence best supports the claim that South showed the largest increase?

  1. South rose from 39 to 63, an increase of 24, larger than North's 16 and Central's 3.
  2. South ended at 63 while North began at 42.
  3. Central began at 51, the largest starting value.
  4. All three locations increased.
  1. Step 1

    Compute or compare each before-after gap.

  2. Step 2

    Keep the series paired within each category.

  3. Step 3

    Select the statement that establishes largest increase, not merely largest final value.

Choice A compares within-site changes across all sites.

Why each choice works or fails

  1. Correct: it reports all three changes accurately.
  2. Wrong comparison: it mixes different sites and time points.
  3. True but irrelevant to change.
  4. Too general: it does not establish which increase was largest.

Common traps and wrong-answer patterns

Mini check

Mini check

A grouped graph shows A: 30/45, B: 44/48, C: 25/49. Which category has the largest increase?

  1. A
  2. B
  3. C
  4. A and B
Show answer and explanation

Answer: C

The increases are 15, 4, and 24, respectively.

Key takeaways

Key takeaways

What to remember

  • Attach every bar to both its category and series.
  • Read scale and units before comparing heights.
  • Match the comparison type to the claim.
  • Use exact values to confirm visual impressions.
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Put these notes into practice

Apply the ideas with SAT-style questions, then reinforce key details with flashcards.