I85PREP
⌘ K
TEAS Science study materials
TEAS Science study resources

TEAS Science practice questions

One question at a time. Build your TEAS Science understanding.

First 50 of 197 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Reading

A reader wants to find the single most important point an author makes about a topic. Which element of a passage usually states that point most directly?

  1. The list of supporting statistics
  2. The final sentence of each paragraph
  3. The title of the reference list
  4. The thesis or main idea statement Correct answer.

Explanation

The main idea is the central claim a passage develops, and it is usually stated in a thesis sentence or topic sentence. Supporting details and citations exist to back that claim rather than to state it. Titles and reference lists organize material but rarely carry the author's central argument.

Question 2Reading

Read this sentence: 'Because the clinic extended its hours, more patients scheduled evening appointments.' Which part of the sentence expresses the cause?

  1. evening appointments
  2. the clinic
  3. more patients scheduled evening appointments
  4. the clinic extended its hours Correct answer.

Explanation

A cause-and-effect relationship links a reason to a result, and signal words such as 'because' introduce the cause. Here the extension of hours is the reason, and the increase in scheduling is the result. The remaining phrases are participants or objects within the result clause.

Question 3Reading

A passage describes how a city added bike lanes, then reports a rise in bicycle commuting, and finally concludes that the lanes encouraged cycling. Which type of reasoning does the passage use?

  1. Chronological narration
  2. Problem and solution
  3. Cause and effect Correct answer.
  4. Comparison and contrast

Explanation

The passage links an action to a later outcome and draws a conclusion that the first produced the second, which is cause-and-effect reasoning. Chronological order would simply narrate events without asserting influence. Comparison and problem-solution structures would require different organizing signals.

Question 4Reading

In a passage, the word 'volatile' appears in the sentence 'The volatile compound evaporated before the lid was replaced.' Using the context, what does 'volatile' most nearly mean?

  1. Difficult to detect
  2. Chemically stable
  3. Easily vaporized Correct answer.
  4. Highly toxic

Explanation

Context clues show the compound evaporated quickly, so 'volatile' describes a tendency to vaporize readily. Toxicity, stability, and detectability are unrelated properties that the sentence does not support. Substituting each option into the sentence confirms only the first fits the evaporation clue.

Question 5Reading

An author writes, 'Requiring students to wear uniforms will surely eliminate bullying in schools.' Which statement best evaluates this claim?

  1. It is a neutral observation with no persuasive intent
  2. It is a definition that clarifies the term 'uniform'
  3. It is a verifiable fact supported by school records
  4. It is an overgeneralization that asserts an absolute outcome Correct answer.

Explanation

The word 'surely' plus the absolute outcome 'eliminate bullying' signals an overgeneralization that goes beyond what evidence could support. A verifiable fact would be stated in measurable terms rather than as a guaranteed result. The sentence makes a persuasive prediction rather than defining a term.

Question 6Reading

A paragraph opens with 'First, the nurse checks the patient's identification.' Later sentences begin with 'Next' and 'Finally.' Which organizational pattern does the paragraph use?

  1. Definition
  2. Comparison
  3. Spatial description
  4. Sequence Correct answer.

Explanation

Transition words such as 'first,' 'next,' and 'finally' signal a sequence that orders steps in time. Spatial description would use position words like above or beside. Comparison and definition structures rely on different signal words and purposes.

Question 7Reading

Read this sentence: 'The technician calibrated the instrument, and then she recorded the readings.' Which revision best combines the two ideas while keeping the time relationship clear?

  1. The technician calibrated the instrument and recorded the readings afterward Correct answer.
  2. The technician recorded the readings and calibrated the instrument first
  3. Calibrating the instrument, the readings were recorded by the technician
  4. The technician calibrated the instrument, but she recorded the readings

Explanation

The original sentence presents calibration before recording, and the best revision preserves that order with a clear time signal such as 'afterward.' Replacing the link with 'but' changes the relationship to contrast. A dangling modifier misplaces the actor, and reversing the order distorts the sequence.

Question 8Reading

A reader encounters the unfamiliar word 'auscultation' in a clinical passage. Which strategy best uses the surrounding text to infer its meaning?

  1. Looking for nearby words that describe the same action Correct answer.
  2. Counting the syllables in the word
  3. Skipping the word and reading only the headings
  4. Memorizing the spelling of the word

Explanation

Context clues work by locating nearby words or examples that restate or explain an unfamiliar term. Skipping the word loses meaning, and spelling or syllable counts do not reveal what a word means. Effective readers use the surrounding sentence to infer definition.

Question 9Reading

A passage presents a study finding that students who ate breakfast scored higher on a test. Which statement is a reasonable inference rather than a restatement of the finding?

  1. The test was given in the morning
  2. All students who ate breakfast passed the test
  3. Breakfast was served in the school cafeteria
  4. Eating breakfast may be associated with better test performance Correct answer.

Explanation

An inference draws a conclusion that goes slightly beyond the stated facts while remaining supported by them, so linking breakfast with better performance is a reasonable inference. Restating the finding or inventing unstated details is not inference. Claiming that all breakfast eaters passed overstates the evidence.

Question 10Reading

Which sentence uses a transition that correctly signals a contrast between two ideas?

  1. The first method is fast; similarly, the second is slow
  2. The first method is fast; therefore, the second is slow
  3. The first method is fast; however, the second is slow Correct answer.
  4. The first method is fast; for example, the second is slow

Explanation

Contrast transitions such as 'however' signal that the second clause opposes the first. 'Therefore' and 'for example' indicate result and illustration respectively, which do not fit opposing descriptions. 'Similarly' signals agreement, not contrast.

Question 11Reading

A writer needs to determine whether a source is credible for a research paper. Which feature most strongly supports the source's credibility?

  1. It appears first in a search engine result list
  2. It uses colorful graphics and large headings
  3. It is written by an author with relevant credentials and is peer reviewed Correct answer.
  4. It has been shared frequently on social media

Explanation

Credibility rests on author expertise and editorial or peer review, which indicate the information has been vetted. Search ranking, visual design, and social sharing reflect popularity or presentation rather than reliability. A credible source can be verified through its authorship and review process.

Question 12Reading

A passage states: 'The new policy reduced wait times in the emergency department by 20 percent. Staff reported feeling less stressed, and patient complaints dropped.' What is the main idea of the passage?

  1. Wait times are the only important measure of care
  2. Staff stress is unrelated to patient complaints
  3. Emergency departments are usually understaffed
  4. The new policy improved several measures of department performance Correct answer.

Explanation

The main idea summarizes what all the details support, which is that the policy improved wait times, staff stress, and complaints. The other options either introduce unsupported claims or narrow the passage to a single measure. A main idea must account for the whole set of details.

Question 13Reading

Which of these is a primary source for a report on a historical medical discovery?

  1. A wiki article compiled by volunteers
  2. A documentary made decades later
  3. The researcher's original published paper from the time Correct answer.
  4. A textbook chapter summarizing the discovery

Explanation

A primary source is a firsthand record created by a participant or at the time of the event, such as the original research paper. Textbooks, later documentaries, and volunteer-compiled articles are secondary because they interpret or summarize other sources. Distinguishing primary from secondary depends on directness to the original event.

Question 14Reading

Read this sentence: 'Neither the students nor the instructor was aware of the schedule change.' Which statement about the sentence is accurate?

  1. The verb should be plural because two subjects appear
  2. The verb agrees with the nearer subject, 'instructor' Correct answer.
  3. The sentence lacks a complete predicate
  4. The sentence contains a dangling modifier

Explanation

With 'neither...nor,' the verb agrees with the subject closer to it, which is the singular 'instructor,' so the singular 'was' is correct. A plural verb would violate this proximity rule. The sentence has a clear subject and predicate and no dangling modifier.

Question 15Reading

An author uses the phrase 'a double-edged sword' when describing a new technology. What does this figurative expression suggest about the technology?

  1. It has both benefits and drawbacks Correct answer.
  2. It is outdated and no longer used
  3. It is too expensive for most people
  4. It is physically dangerous to handle

Explanation

A double-edged sword is an idiom meaning something that can help and harm at the same time. The phrase refers to mixed consequences rather than physical danger, obsolescence, or cost. Recognizing idioms requires matching the figurative phrase to its conventional meaning.

Question 16Reading

A reader is comparing two articles about the same diet. Article A cites randomized trials; Article B cites anecdotes from a blog. Which conclusion is best supported?

  1. Neither article can be evaluated without reading the titles
  2. Article A is more reliable because it relies on controlled evidence Correct answer.
  3. Article B is stronger because personal stories are more engaging
  4. Both articles are equally reliable because they discuss the same diet

Explanation

Evidence quality determines reliability, and randomized trials provide stronger, more controlled support than anecdotal reports. Shared topic does not equal shared reliability, and engagement is not a measure of accuracy. Anecdotes can illustrate but cannot establish effectiveness.

Question 17Reading

Which sentence correctly uses a colon?

  1. The kit contained: gloves, masks, and swabs
  2. The kit: contained gloves, masks, and swabs
  3. The kit contained gloves: masks, and swabs
  4. The kit contained the following items: gloves, masks, and swabs Correct answer.

Explanation

A colon introduces a list only after a complete independent clause, which 'the following items' supplies. Placing a colon directly after a verb or between list items breaks that rule. Separating a subject from its verb with a colon is also incorrect.

Question 18Reading

A passage argues that a community garden should be built. It notes that residents lack fresh produce, that vacant land is available, and that volunteers have offered to help. Which sentence is the author's claim?

  1. A community garden should be built Correct answer.
  2. Volunteers have offered to help maintain the space
  3. Vacant land is available in the neighborhood
  4. Residents lack access to fresh produce

Explanation

A claim is the position the author wants the reader to accept, which here is the recommendation to build the garden. The other sentences are supporting reasons that provide evidence for that recommendation. Distinguishing claims from support is central to evaluating an argument.

Question 19Reading

A reader is skimming a long chapter to locate a specific statistic. Which reading approach is most efficient?

  1. Memorizing the chapter's introduction
  2. Scanning for numerals and key terms Correct answer.
  3. Reading every sentence at the same slow pace
  4. Rereading the chapter's conclusion twice

Explanation

Scanning is a targeted search for specific information such as numbers or key terms, which makes it efficient for locating a statistic. Uniform slow reading wastes time when only one detail is needed. Memorizing or rereading sections does not directly locate the target.

Question 20Reading

Read this sentence: 'The report, which was written by the committee, was distributed to all members.' Which type of clause is 'which was written by the committee'?

  1. A nonrestrictive relative clause Correct answer.
  2. An independent clause
  3. An adverb clause of condition
  4. A noun clause

Explanation

The clause modifies 'the report' and is set off by commas, showing it adds nonessential information, which makes it a nonrestrictive relative clause. It cannot stand alone, so it is not independent. It does not function as a noun or express a condition.

Question 21Reading

A passage notes that a medication lowered blood pressure in a trial but also caused dizziness in some participants. Which statement best describes the author's purpose?

  1. To entertain readers with a story
  2. To present a balanced report of benefits and side effects Correct answer.
  3. To persuade readers to avoid all medications
  4. To define the term 'blood pressure'

Explanation

The passage reports both a benefit and a side effect, which indicates a balanced informational purpose. Persuading readers to avoid medication would require a one-sided argument, and the passage does not define terms or tell a story. Purpose is inferred from what the author chooses to include.

Question 22Reading

Which sentence is punctuated correctly?

  1. The nurse checked the chart, and then she updated the file Correct answer.
  2. The nurse checked the chart, then she updated the file
  3. The nurse checked the chart and then, she updated the file
  4. The nurse checked the chart and then she updated the file

Explanation

Two independent clauses joined by a coordinating conjunction require a comma before the conjunction. Omitting the comma creates a run-on, and joining clauses with only a comma creates a comma splice. Placing the comma after 'then' misplaces the boundary.

Question 23Reading

An author writes, 'According to the National Safety Council, falls are a leading cause of injury.' What does the attribution 'according to' tell the reader?

  1. The author personally conducted the research
  2. The claim is the author's own opinion
  3. The statement is a fictional example
  4. The information comes from an outside source Correct answer.

Explanation

Attribution phrases such as 'according to' signal that information comes from another source rather than from the author's own work or opinion. This helps readers trace evidence and judge credibility. Recognizing attribution is a key part of evaluating informational texts.

Question 24Reading

A reader wants to summarize a passage accurately. Which approach produces the best summary?

  1. Stating the main idea and the key supporting points briefly Correct answer.
  2. Including the reader's own opinion about the topic
  3. Copying several sentences word for word
  4. Listing every supporting detail in order

Explanation

A summary condenses a text by capturing its main idea and essential supporting points in the writer's own words. Copying sentences is not condensing, and listing every detail defeats brevity. Personal opinion does not belong in an objective summary.

Question 25Reading

In an argument, a writer states that 'most experts agree' without naming any experts or studies. Which flaw does this represent?

  1. A clear definition of a key term
  2. An appeal to authority without specific evidence Correct answer.
  3. A well-supported statistic
  4. A logical comparison between two cases

Explanation

Citing unnamed experts relies on authority without providing verifiable evidence, which weakens the argument. A supported statistic would identify its source and data. The statement neither defines terms nor draws a comparison, so those descriptions do not apply.

Question 26Reading

A passage describes how a city added bike lanes, then reports a rise in bicycle commuting. Which sentence from the passage is the main idea?

  1. The sentence that states the city added bike lanes to encourage commuting. Correct answer.
  2. The sentence that quotes one cyclist's opinion of the lanes.
  3. The sentence that lists the specific streets where lanes were painted.
  4. The sentence that gives the cost of the paint used.

Explanation

A main idea states the central point the rest of the passage supports, which here is that the city added lanes to encourage commuting. Supporting details such as street names, quotes, and costs only illustrate or elaborate on that point.

Question 27Reading

Which statement about a passage's topic differs from its main idea?

  1. The topic is stated only in the title, while the main idea appears only in the body.
  2. The topic is the author's opinion, while the main idea is a factual detail.
  3. The topic is the subject being discussed, while the main idea is the point made about it. Correct answer.
  4. The topic is always the first sentence, while the main idea is always the last sentence.

Explanation

The topic is the broad subject of a passage, whereas the main idea is the claim or point the author makes about that subject. Position within the passage is not what distinguishes the two.

Question 28Reading

Read the sentence: 'The nurse spoke quietly to the child, and the child stopped crying.' Which relationship does the conjunction 'and' show between the two clauses?

  1. Contrast between opposing outcomes
  2. A condition that must be met
  3. Addition of a related event Correct answer.
  4. A cause that explains the first clause

Explanation

The coordinating conjunction 'and' joins two clauses that are both true and related, adding one event to another. It does not signal contrast, condition, or causation.

Question 29Reading

A passage says: 'The clinic extended its hours to 9 p.m. As a result, evening appointments increased by 40 percent.' Which word signals the relationship between the two sentences?

  1. increased
  2. evening
  3. As a result Correct answer.
  4. extended

Explanation

'As a result' is a transition that signals cause and effect, linking the longer hours to the rise in appointments. The other words are ordinary content words, not transition signals.

Question 30Reading

Which sentence uses a semicolon correctly?

  1. The lab was closed; and the samples were stored overnight.
  2. The lab was closed, the samples; were stored overnight.
  3. The lab; was closed, so the samples were stored overnight.
  4. The lab was closed; therefore, the samples were stored overnight. Correct answer.

Explanation

A semicolon may join two independent clauses, often with a conjunctive adverb such as 'therefore' followed by a comma. It should not be placed before a coordinating conjunction like 'and' or inside a clause that has not ended.

Question 31Reading

A reader finds the word 'triage' in a passage about emergency care. Which approach best uses context to infer its meaning?

  1. Skip the word and continue reading without checking its meaning.
  2. Look only at the word's first letter to guess its category.
  3. Examine the nearby sentences describing how patients are ranked by urgency. Correct answer.
  4. Assume the word means the same as the most similar word the reader already knows.

Explanation

Context clues come from the surrounding sentences, which here describe ranking patients by urgency. Using only a word's spelling or an unrelated guess does not reliably reveal meaning.

Question 32Reading

Which of these is a secondary source for a report on a historical nursing practice?

  1. A textbook chapter summarizing several studies of the practice Correct answer.
  2. A photograph taken at the hospital during the period
  3. A letter written by a nurse who performed the practice
  4. A nurse's original handwritten shift log from the period

Explanation

A secondary source interprets or summarizes information gathered from primary sources, such as a textbook chapter reviewing studies. Original logs, photographs, and letters created during the period are primary sources.

Question 33Reading

Which sentence uses a comma correctly?

  1. After the test ended, the students left the room. Correct answer.
  2. After the test ended the students, left the room.
  3. After the test, ended the students left the room.
  4. After, the test ended the students left the room.

Explanation

An introductory dependent clause is followed by a comma before the main clause begins. Placing the comma elsewhere breaks the flow of the clauses and misleads the reader.

Question 34Reading

A passage states: 'Many students report feeling stressed before exams. The university should therefore offer free tutoring.' Which type of reasoning does the passage use?

  1. It quotes an expert's published opinion.
  2. It draws a recommendation from a reported problem. Correct answer.
  3. It describes a controlled experiment.
  4. It compares two unrelated statistics.

Explanation

The passage presents a problem (student stress) and then recommends an action (free tutoring) as a response. This is a problem-and-solution pattern of reasoning rather than an experiment or comparison.

Question 35Reading

A writer claims a new study proves a diet is safe. The study actually followed participants for only two weeks. Which statement best evaluates the claim?

  1. The claim is valid because any study result proves a general conclusion.
  2. The claim is valid because short studies are always more reliable.
  3. The claim is too strong because a two-week study cannot establish long-term safety. Correct answer.
  4. The claim is irrelevant because diet studies are never useful.

Explanation

A conclusion is only as strong as the evidence behind it, and a two-week study cannot support a claim about long-term safety. Overgeneralizing beyond the study's scope is a reasoning flaw.

Question 36Reading

An author writes, 'The proposal is a recipe for disaster.' What does this figurative language suggest about the proposal?

  1. It is too complicated to understand.
  2. It involves cooking and food preparation.
  3. It has been carefully tested and approved.
  4. It is likely to produce harmful results. Correct answer.

Explanation

The metaphor compares the proposal to a recipe for disaster, implying it will lead to bad outcomes. Figurative language conveys meaning through comparison rather than literal description.

Question 37Reading

A reader needs to compare the conclusions of two long articles quickly. Which approach is most efficient?

  1. Read each article's abstract and final paragraph first. Correct answer.
  2. Read the reference lists at the end of each article.
  3. Read only the first sentence of each article.
  4. Read every sentence of both articles from start to finish.

Explanation

Abstracts and concluding paragraphs summarize an article's purpose and findings, allowing efficient comparison. Reading everything or only the opening sentence is either inefficient or incomplete.

Question 38Reading

Read the sentence: 'Although the medication relieved pain, it caused drowsiness.' Which relationship does 'although' establish?

  1. A sequence of events in time
  2. Concession between a benefit and a drawback Correct answer.
  3. Addition of two similar benefits
  4. A definition of the medication

Explanation

'Although' introduces a concession, acknowledging a benefit while pointing to a contrasting drawback. It signals contrast rather than addition, sequence, or definition.

Question 39Reading

A passage includes the sentence: 'The survey, which was conducted online, reached 500 participants.' What is the function of the clause 'which was conducted online'?

  1. It adds descriptive detail about the survey. Correct answer.
  2. It introduces a contrasting idea.
  3. It gives the cause of the survey's results.
  4. It states the main action of the sentence.

Explanation

A relative clause beginning with 'which' provides extra descriptive information about the noun it follows. It is subordinate and does not carry the sentence's main action or introduce contrast or causation.

Question 40Reading

A writer wants to support a claim that a hospital's handwashing policy reduced infections. Which evidence would be strongest?

  1. Infection rates before and after the policy took effect Correct answer.
  2. An advertisement describing the hospital's services
  3. A general statement that handwashing is important
  4. A patient's opinion that the hospital seemed cleaner

Explanation

Before-and-after infection rates directly measure whether the policy changed outcomes, making them the strongest support. Opinions, general statements, and advertisements do not measure the policy's effect.

Question 41Reading

Which sentence correctly uses quotation marks and punctuation?

  1. The instructor said, "Submit your report by Friday".
  2. The instructor said "Submit your report by Friday".
  3. The instructor said, "Submit your report by Friday." Correct answer.
  4. The instructor said "Submit your report by Friday,".

Explanation

A comma introduces a direct quotation, the quoted sentence begins with a capital letter, and the period stays inside the closing quotation mark. Misplacing the period or the comma breaks these conventions.

Question 42Reading

A passage describes a town that installed solar panels and then notes lower electricity bills. A reader concludes the panels caused the savings. Which assumption underlies this conclusion?

  1. The town installed the panels without any planning.
  2. Solar panels are always cheaper than other power sources.
  3. Electricity bills are the only measure of energy use.
  4. No other factor, such as lower energy prices, caused the savings. Correct answer.

Explanation

Concluding that the panels caused the savings assumes nothing else changed that could explain the result. If energy prices fell for other reasons, the causal claim would be weakened.

Question 43Reading

A reader is summarizing a passage about vaccination. Which summary is best?

  1. It copies several sentences word for word from the passage.
  2. It lists every statistic mentioned in the passage.
  3. It briefly restates the passage's main points in the reader's own words. Correct answer.
  4. It adds the reader's personal opinions about vaccination.

Explanation

A good summary condenses the main points and restates them in the reader's own words without adding opinions. Copying, adding opinion, or listing every detail does not produce an accurate summary.

Question 44Reading

An author writes, 'The data are clear: exercise improves mood.' Which statement best describes the author's tone?

  1. Humorous and playful
  2. Confident and assertive Correct answer.
  3. Uncertain and hesitant
  4. Apologetic and defensive

Explanation

Phrases such as 'the data are clear' convey certainty and directness, which define a confident tone. The sentence contains no markers of hesitation, humor, or apology.

Question 45Reading

A passage presents two studies with opposite results on the same topic. Which reading approach best helps a reader evaluate the conflict?

  1. Choose the study whose conclusion seems more familiar.
  2. Accept the study that was published first.
  3. Reject both studies as useless.
  4. Compare the studies' methods, sample sizes, and populations. Correct answer.

Explanation

When sources conflict, examining methodology, sample size, and population reveals which findings are more trustworthy or whether the studies are truly comparable. Choosing by publication order or familiarity ignores the evidence.

Question 46Reading

A writer uses the phrase 'the silent epidemic' to describe a health condition. What does this phrase most likely emphasize?

  1. The condition affects only a small number of people.
  2. The condition makes people unable to speak.
  3. The condition is caused by loud noises.
  4. The condition spreads widely while receiving little public attention. Correct answer.

Explanation

'Silent epidemic' figuratively combines widespread occurrence with a lack of awareness, suggesting a condition that spreads unnoticed. It is not a literal reference to speech or noise.

Question 47Reading

A passage argues: 'All effective teachers use group work. Ms. Rivera uses group work. Therefore, Ms. Rivera is an effective teacher.' Which statement identifies the flaw?

  1. The argument uses no premises at all.
  2. The argument treats a necessary condition as sufficient, so group work alone does not guarantee effectiveness. Correct answer.
  3. The argument draws a conclusion unrelated to its premises.
  4. The argument relies on a contradiction between its premises.

Explanation

The first premise says effective teachers use group work, which makes group work necessary but not sufficient. Concluding effectiveness from group work alone reverses the logic.

Question 48Reading

A passage states a statistic but omits the source and the sample size. What is the most reasonable response from a careful reader?

  1. Treat the statistic cautiously until its source and basis can be verified. Correct answer.
  2. Accept the statistic because numbers are always objective.
  3. Ignore the statistic and focus only on the author's opinions.
  4. Assume the statistic is false and stop reading.

Explanation

A statistic without a source or sample size cannot be verified, so a careful reader suspends judgment until more information is available. Accepting or rejecting it outright both skip the needed verification.

Question 49Reading

Read the sentence: 'The committee reviewed the proposal, and it approved the plan after lengthy debate.' Which revision most improves clarity?

  1. The committee reviewed the proposal, and it approved it after it debated it.
  2. The committee reviewed the proposal and approved the plan after lengthy debate. Correct answer.
  3. The committee reviewed, the proposal and approved the plan, after lengthy debate.
  4. The committee, and it, reviewed the proposal approved the plan after debate.

Explanation

Removing the comma and the vague pronoun 'it' produces a clear compound predicate with one subject. The other revisions add ambiguity or misplaced punctuation.

Question 50Reading

A passage presents a single case study as proof that a treatment works for everyone. Which criticism is most accurate?

  1. A case study is the strongest possible form of evidence.
  2. One case cannot establish that a treatment works for a broad population. Correct answer.
  3. Case studies are useful only when they include statistics.
  4. The criticism is invalid because case studies prove general claims.

Explanation

A single case provides limited evidence and cannot support a general claim about an entire population. Broader, controlled evidence is needed to establish effectiveness for everyone.