Command of Evidence: Textual vs. Quantitative

What You Need to Know

Command of Evidence questions test whether you can prove an answer using the passage (textual evidence) or using numbers in a graphic (quantitative evidence like tables, charts, and graphs). On PSAT $8/9$, these show up in both Reading and Writing & Language.

The core skill

You must choose the option that is best supported by:

• Textual evidence: specific words/lines/sentences in the passage.
• Quantitative evidence: specific values, comparisons, or trends in a graph/table.

Your job is not to pick something that is “true in real life.” Your job is to pick what the passage/data actually supports.

The two main question styles

1. Paired questions (Reading)

   • Q1: What does the passage imply/claim/answer?
   • Q2: Which lines best support your answer?

2. Data-based evidence (Reading or Writing)

   • “Which choice best describes what the graph/table shows?”
   • “Which revision is best supported by the data?”
   • “Which statement is supported/contradicted by the figure?”

Textual vs. Quantitative evidence (quick contrast)

• Textual: precision in meaning and context (tone, purpose, inference).
• Quantitative: precision in numbers and definitions (units, axes, categories, what’s being measured).

Step-by-Step Breakdown

A. Textual Command of Evidence (especially paired questions)

Use this when answers must be backed by lines or specific wording.

1. Label the job of the question

   • Is it asking for main idea, inference, purpose, definition-in-context, or support?

2. Answer in your own words first

   • Make a short “claim” you’re trying to prove.

3. Go to the passage and find the exact spot

   • Use keywords from the question/answers.
   • Read $2$–$4$ lines before and after a quoted line reference.

4. Check each answer choice like evidence in court

   • Ask: “Does this choice directly prove my claim?”
   • Prefer evidence that is:
     • Specific (not vague)
     • Relevant (about the same idea)
     • Complete (captures the full point, not just a fragment)

5. Eliminate trap evidence

   • True but irrelevant
   • Too broad / too narrow
   • Mentions the right topic but supports a different conclusion

If you’re stuck on the first question in a paired set

Try evidence-first:

• Skim the evidence options (line quotes).
• Summarize what each quoted chunk is saying.
• Pick the first-question answer that matches one chunk clearly.

B. Quantitative Command of Evidence (graphs/tables)

Use this when an answer must be supported by data.

1. Read the “data labels” before the data

   • What does the title say?
   • What are the axes?
   • What are the units?
   • What categories/groups are being compared?

2. Translate the claim into a measurable check
   Turn words into math/comparisons:

   • “increased” $\rightarrow$ later value $>$ earlier value
   • “decreased” $\rightarrow$ later value $<$ earlier value
   • “about the same” $\rightarrow$ values close together
   • “highest/lowest” $\rightarrow$ max/min
   • “majority” $\rightarrow$ more than half
   • “twice as much” $\rightarrow$ ratio about $2:1$

3. Locate the exact data points needed

   • Don’t eyeball if the graph gives exact values.
   • If it’s a bar/line graph without labels, estimate carefully using tick marks.

4. Compute only what you need
   Common quick computations:

• Difference: $\text{difference} = a - b$
• Percent change: $\text{percent change} = \frac{\text{new} - \text{old}}{\text{old}} \times 100\%$
• Average (mean): $\text{mean} = \frac{\text{sum of values}}{\text{number of values}}$

1. Match wording exactly
   A statement can be “almost true” but wrong because it says:

• “always” vs “sometimes”
• “caused” vs “was associated with”
• “most” vs “some”

For quantitative evidence, one wrong word (like “doubled” vs “increased”) kills the choice.

Key Formulas, Rules & Facts

A. Evidence rules (Textual)

B. Data rules (Quantitative)

C. Quick quantitative reference (high-frequency relationships)

Examples & Applications

Example 1 (Textual, paired evidence)

Mini-passage (original):

“While the town council praised the new bike lanes for improving safety, several shop owners worried that fewer parking spaces would reduce customer visits. After three months, however, most owners reported that weekend foot traffic had increased.”

Q1: The passage most strongly suggests that the shop owners’ concerns were

• A) proven correct immediately
• B) not supported by the short-term results
• C) ignored by the town council
• D) shared by most residents

Q2: Which choice best supports the answer to Q1?

• A) “praised the new bike lanes for improving safety”
• B) “worried that fewer parking spaces would reduce customer visits”
• C) “After three months, however, most owners reported”
• D) “weekend foot traffic had increased”

Key insight: Q1 is about whether the concern came true. The passage says foot traffic increased, which goes against “reduce customer visits.”

• Best Q1: B
• Best evidence: D (most direct proof), with C as context but less complete alone.

Example 2 (Textual, trap: true but irrelevant)

Mini-passage (original):

“The scientist carefully described the new method in the journal article. She added that future studies would test the method in different climates.”

Question: Which line best supports the idea that the method is not fully confirmed yet?

• A) “carefully described the new method”
• B) “in the journal article”
• C) “future studies would test the method”
• D) “different climates”

Key insight: “Not fully confirmed” is supported by needing future studies.

• Best answer: C
• Trap: A is positive but doesn’t prove uncertainty.

Example 3 (Quantitative, table to support a statement)

Table (original): Average daily water use per person

Question: Which statement is best supported by the data?

• A) Water use decreased every year from $2020$ to $2023$.
• B) Water use decreased most sharply between $2022$ and $2023$.
• C) Water use decreased by $25\%$ from $2020$ to $2023$.
• D) Water use will be below $120$ in $2024$.

Work (minimal):

• Decrease each year: $140 \to 135 \to 130 \to 125$ (always down) $\Rightarrow$ A is supported.
• Each drop is $5$, so “most sharply” (B) is not supported.
• Percent change: $\frac{125-140}{140} \times 100\% = \frac{-15}{140} \times 100\% \approx -10.7\%$, not $-25\%$ $\Rightarrow$ C is wrong.
• D extrapolates beyond data $\Rightarrow$ wrong.

Best answer: A

Example 4 (Quantitative + wording precision)

Graph description (original): A survey shows:

• Group A: $60\%$ prefer option X
• Group B: $55\%$ prefer option X

Question: Which claim is supported?

• A) Option X is preferred by a majority in both groups.
• B) Group A prefers option X twice as much as Group B.
• C) Option X causes higher satisfaction in Group A.
• D) Exactly $5\%$ more people prefer X in Group A than in Group B.

Key insight:

• “Majority” means $>50\%$ $\Rightarrow$ A is supported.
• “Twice as much” would require about $2\times$ $55\%$, not close.
• “Causes” is too strong.
• D is tricky: it says $5\%$ more **people**, but data shows $5$ percentage points. If the groups have different sizes, “people” isn’t guaranteed. Without group sizes, D is not safely supported.

Best answer: A

Common Mistakes & Traps

1. Picking an answer that’s true in real life but not in the passage/data

   • Why wrong: PSAT evidence questions are closed-universe.
   • Fix: Prove every claim with a specific line or number.

2. Using the right lines for the wrong idea (topic-match trap)

   • What happens: You see a familiar keyword and pick it.
   • Why wrong: The quote mentions the topic but supports a different conclusion.
   • Fix: Paraphrase your claim first, then ask if the quote answers that exact claim.

3. Ignoring context around the quoted lines

   • What happens: You read only the quoted sentence.
   • Why wrong: Nearby lines can flip the meaning (contrast words like “however,” “although”).
   • Fix: Always read a small window around the quote.

4. Choosing evidence that is too broad

   • What happens: You pick a general statement.
   • Why wrong: Another option usually gives more direct proof.
   • Fix: Prefer the choice that names the specific reason/example.

5. Quantitative: Misreading axes, scale, or units

   • What happens: You compare heights but miss that the y-axis ticks jump by $10$ or the unit is “per $1000$.”
   • Fix: Read title, axes labels, tick marks, and units before interpreting.

6. Quantitative: Mixing up percent and percentage points

   • What happens: You treat $60\% - 55\%$ as “$5\%$ more people” in a literal headcount sense.
   • Fix: Say “$5$ percentage points” unless group sizes are given.

7. Quantitative: Overstating what data can prove (causation trap)

   • What happens: You choose “X causes Y” from a simple comparison.
   • Fix: Unless the passage describes a controlled experiment and explicitly claims causation, stick to “is associated with” or “corresponds to.”

8. Falling for extreme wording

   • What happens: You choose “always,” “never,” “completely proves.”
   • Why wrong: Most passages/data support nuanced claims.
   • Fix: Match strength: if the data shows “often,” don’t pick “always.”

Memory Aids & Quick Tricks

These aren’t official test mnemonics—just reliable shortcuts you can use under time pressure.

Quick Review Checklist

• You can restate the question as a claim you must prove.
• For textual evidence, you:
  • read surrounding context
  • choose the line(s) that most directly support the claim
  • avoid “true but irrelevant” quotes
• For paired questions, your evidence must support your chosen answer, not a different one.
• For quantitative evidence, you:
  • read title/axes/units/legend first
  • check the exact numbers (or careful estimates)
  • match wording strength (no “causes,” no “always” unless proven)
  • avoid extrapolation beyond the displayed data
• You double-check tricky language: most vs some, percent vs number, percentage points vs percent, associated with vs causes.

You’ve got this—treat every answer like it must survive a strict “prove it” test.