ACT Reading: Identify How Authors Use Evidence to Build Arguments Persuasively

Type 1: Statistical data (numbers, percentages, research findings). Strength: Objective and measurable. Weakness: Can be outdated or misinterpreted. Type 2: Expert testimony (quotes from authoritative figures). Strength: Credibility of the expert backs the claim. Weakness: Only as strong as the expert's reputation. Type 3: Anecdotal evidence (personal stories, examples). Strength: Relatable and memorable. Weakness: May not represent broader patterns. Type 4: Logical reasoning (if-then statements, cause-effect). Strength: Transparent and traceable. Weakness: Only valid if premises are correct. Type 5: Historical precedent (past examples or cases). Strength: Shows pattern or tradition. Weakness: Past situations may not apply today. Strong arguments combine multiple evidence types; weak arguments rely on one type or on evidence that does not directly support the claim.

Example: An argument for a ban on plastics uses statistics (tons of plastic in oceans), expert testimony (marine biologist), and examples (whale with plastic in stomach). This is strong because three evidence types reinforce each other. An argument that only includes one anecdote is weak because it does not represent a trend.

Mistake 1: Assuming all statistics are equally strong. A statistic from a major research study is stronger than a statistic from a small survey. Check the source: who conducted the research? How large was the sample? How recent? Mistake 2: Accepting expert testimony without questioning expertise. A celebrity endorsing a health product is not a valid expert witness. A cardiologist endorsing it is. Always ask: Is the evidence type appropriate for this claim? Is the source credible? Is the evidence recent or timeless enough?

On the ACT, if a question asks "Which evidence best supports the author's claim?", eliminate choices with weak evidence types or weak sources. Pick the choice that is most directly relevant and most credible.

Claim: "High school students should study at least one hour per day." Evidence 1: "A student said she improved from a C to an A after studying one hour daily." (Anecdotal. Weak; single example.) Evidence 2: "Research shows students who study one hour daily score on average 5% higher on standardized tests." (Statistical. Stronger; objective and measurable.) Evidence 3: "Teachers recommend one hour of daily study." (Expert testimony. Moderate; teachers are qualified but may be biased.) Evidence 4: "One hour of daily study allows time to review concepts and prepare for tests." (Logical reasoning. Moderate; makes sense but does not prove the claim.) Strongest combination: Evidence 2 (statistics) plus Evidence 3 (expert) plus Evidence 4 (logic). For a claim about study habits, statistical evidence showing improved outcomes is strongest because it directly measures the effect of the practice.

On the next ACT Reading practice test, find an argumentative passage. Mark each piece of evidence and evaluate its type and strength. Note which evidence types the author uses and whether the combination is persuasive. Check your evaluation against the answer choices.

Understanding evidence appears in reading comprehension, writing, and research across all college subjects. The ACT tests this skill through questions about argument quality and evidence strength. Students who can analyze evidence construct stronger arguments in their own writing and evaluate sources critically in research, making them better prepared for college-level work.

This week, read two argumentative articles on the same topic but from different sources. For each, identify the evidence types used and evaluate their strength. Compare which article makes the more persuasive argument based on evidence quality. By test day, you will instinctively evaluate evidence on the ACT and in real-world reading.