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LTF12 practice questions

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Question 1Unverified - official content outline not available (placeholder domain pending source)

Which item is best described as a primary source for a study of early twentieth-century public health policy?

  1. A documentary film made in 2005 about the reforms
  2. A journal article reviewing recent histories of the period
  3. A government sanitation report published in 1911 Correct answer.
  4. A textbook chapter summarising several public health reforms

Explanation

A primary source is a document or record created at the time under study by a participant or witness. A 1911 government sanitation report fits that definition because it originated within the period and directly documents policy. Later summaries, documentaries, and review articles interpret or synthesise primary material and are therefore secondary.

Question 2Unverified - official content outline not available (placeholder domain pending source)

What is the main purpose of peer review before publication?

  1. To standardise spelling, layout, and reference formatting
  2. To obtain independent expert assessment of validity Correct answer.
  3. To confirm the author's institutional affiliation and funding
  4. To guarantee that the results will be replicated later

Explanation

Peer review asks independent experts to evaluate a manuscript's methods, evidence, and conclusions before publication. It is a quality-control step, not a guarantee of replication or agreement with editors. Copy-editing and affiliation checks are separate editorial tasks.

Question 3Unverified - official content outline not available (placeholder domain pending source)

Which action constitutes plagiarism?

  1. Paraphrasing a source and naming the original author in the text
  2. Summarising another author's idea and citing the source fully
  3. Using another author's paragraph without attribution Correct answer.
  4. Quoting exactly and placing the words in quotation marks with a citation

Explanation

Plagiarism is the presentation of someone else's words or ideas as one's own without adequate attribution. Citing, quoting with quotation marks, and naming the original author are accepted ways to avoid it. Using a paragraph without credit conceals its source and misrepresents authorship.

Question 4Unverified - official content outline not available (placeholder domain pending source)

A study finds that students who eat breakfast score higher on a test. Which conclusion is most justified?

  1. Eating breakfast is proven to raise test scores for every student
  2. Breakfast has no relationship with test performance
  3. Test scores determine whether students eat breakfast
  4. The data show an association; causation needs more evidence Correct answer.

Explanation

An observed association between breakfast and test scores does not by itself establish which factor causes the other. Students who eat breakfast may differ in income, sleep, or study habits, and these variables could influence scores. A causal claim requires controlled or longitudinal evidence that rules out such alternatives.

Question 5Unverified - official content outline not available (placeholder domain pending source)

A researcher surveys visitors at a gym about their weekly exercise habits. What is the main limitation of this sample?

  1. Gym visitors always report inaccurate exercise habits
  2. Weekly exercise is impossible to define precisely
  3. The sample may overrepresent regular exercisers Correct answer.
  4. The survey cannot measure exercise frequency at all

Explanation

A gym sample is a convenience sample drawn from people who already exercise, so it is likely to overrepresent regular exercisers. This selection bias limits how well the findings generalise to the wider population. The problem is representativeness, not the impossibility of measuring exercise.

Question 6Unverified - official content outline not available (placeholder domain pending source)

Why should a writer include a reference list entry for a source used in an essay?

  1. To allow readers to locate and verify the source Correct answer.
  2. To replace all in-text citations in the essay
  3. To prove the writer read every page of the source
  4. To make the essay appear longer and more detailed

Explanation

A reference list gives the bibliographic details readers need to find each cited source. It supports verification, further reading, and academic accountability. It does not replace in-text citations, which mark the specific points where sources are used.

Question 7Unverified - official content outline not available (placeholder domain pending source)

A student needs detailed methodology to replicate a study. Which section should the student read?

  1. The title and keywords, which aid discovery
  2. The acknowledgements, which credit assistance
  3. The methods section of the full article Correct answer.
  4. The abstract, which summarises the whole study

Explanation

The methods section describes participants, materials, procedures, and analysis in enough detail for replication. The abstract is only a summary, and the title and keywords help with discovery rather than procedural detail. Acknowledgements credit assistance and do not report the study design.

Question 8Unverified - official content outline not available (placeholder domain pending source)

Two studies report statistically significant improvements. Study A's effect is tiny, while Study B's effect is large. What is the best interpretation?

  1. Study A's result must be invalid because its effect is very small
  2. The two results cannot be compared in any useful way at all
  3. Statistical significance proves that Study B was better designed
  4. Study B's effect is more practically meaningful Correct answer.

Explanation

Statistical significance indicates that an observed effect is unlikely to be due to chance alone, but it says nothing about the size or practical importance of the effect. A large effect can be more meaningful than a tiny one even when both are significant. Study design quality must be judged separately from the p-value.

Question 9Unverified - official content outline not available (placeholder domain pending source)

A reviewer searches only for evidence supporting a preferred theory. Which reasoning flaw is most evident?

  1. Anchoring to the first source that the reviewer found
  2. Confusing correlation with causation in the data
  3. Seeking only confirming evidence Correct answer.
  4. Overgeneralising from a very small sample of cases

Explanation

Confirmation bias is the tendency to search for, interpret, and recall information in ways that support existing beliefs. A reviewer who looks only for supportive evidence is filtering out potentially disconfirming data. Anchoring, small-sample overgeneralisation, and correlation-causation confusion are different errors.

Question 10Unverified - official content outline not available (placeholder domain pending source)

A scale consistently gives the same reading for the same object, but the reading is always 2 kg too high. What does this illustrate?

  1. High reliability but poor validity Correct answer.
  2. Neither reliable nor valid in any respect
  3. High validity combined with low reliability
  4. Low reliability combined with high validity

Explanation

Reliability concerns consistency of measurement, while validity concerns whether the measurement captures the intended construct. A scale that always reads 2 kg too high is consistent across trials, so it is reliable, but the systematic error means it does not measure true weight accurately. Thus reliability can be high while validity is poor.

Question 11Unverified - official content outline not available (placeholder domain pending source)

What is the defining feature of a secondary source in academic research?

  1. It provides raw data that have not been processed or interpreted by anyone.
  2. It lists only sources that the author has not directly read or consulted.
  3. It presents firsthand evidence collected by the author at the time of the event.
  4. It interprets or analyzes information originally presented in another source. Correct answer.

Explanation

A secondary source describes, interprets, or analyzes primary information rather than reporting direct, firsthand evidence. Textbooks, review articles, and commentaries are common examples because they synthesize earlier work. The key distinction is the relationship to the original evidence, not the publication format.

Question 12Unverified - official content outline not available (placeholder domain pending source)

What is the main function of an abstract in a scholarly article?

  1. To summarize the study's purpose, methods, findings, and conclusions. Correct answer.
  2. To provide a complete reference list for all works cited in the article.
  3. To describe the author's personal background and academic qualifications.
  4. To acknowledge funding sources and institutional support for the project.

Explanation

An abstract is a concise summary placed at the start of a scholarly article. It tells readers what the study examined, how it was conducted, what was found, and what the authors conclude. Readers use it to decide whether the full article is relevant to their work.

Question 13Unverified - official content outline not available (placeholder domain pending source)

What does informed consent primarily require from participants in a research study?

  1. That they receive payment for any time spent on the study.
  2. That they allow their personal data to be shared publicly.
  3. That they agree to remain in the study until it is completed.
  4. That they understand the study's purpose, risks, and right to withdraw. Correct answer.

Explanation

Informed consent requires that prospective participants receive clear information about the study's purpose, procedures, risks, and benefits, and that they voluntarily agree to take part. It also includes the right to withdraw at any time without penalty. Consent must be documented in an appropriate way.

Question 14Unverified - official content outline not available (placeholder domain pending source)

A researcher wants to reduce social desirability bias in a survey about illegal downloading habits. Which approach is most appropriate?

  1. Use a self-administered anonymous online questionnaire. Correct answer.
  2. Increase the length of the survey to cover more topics.
  3. Conduct the survey in a public setting with other people present.
  4. Ask participants to sign their names to each response.

Explanation

Social desirability bias occurs when respondents give answers they believe are more socially acceptable. Anonymous self-administration reduces the pressure to appear virtuous because responses cannot be linked to the individual. Public settings and signed responses would likely increase the bias.

Question 15Unverified - official content outline not available (placeholder domain pending source)

What is the main difference between anonymity and confidentiality in research?

  1. Anonymity means participant data are shared openly, while confidentiality means data are sold to research sponsors.
  2. Anonymity applies only to quantitative research designs, while confidentiality applies only to qualitative research designs.
  3. Anonymity means only the participant's name is hidden, while confidentiality means all data are destroyed after the study.
  4. Anonymity means data cannot be linked to a person; confidentiality means the researcher keeps identities private. Correct answer.

Explanation

Anonymity exists when the researcher cannot identify which participant provided which data. Confidentiality exists when the researcher can identify participants but agrees not to disclose their identities. Both protect participants, but they describe different levels of identifiability.

Question 16Unverified - official content outline not available (placeholder domain pending source)

A researcher compares two existing classrooms that were not assigned by the researcher. One classroom uses a new teaching method, and the other uses a traditional method. What type of design is this?

  1. Randomized controlled trial
  2. Case study design
  3. Quasi-experimental design Correct answer.
  4. Correlational design

Explanation

A quasi-experimental design compares groups that are not formed by random assignment. Because the researcher did not randomly assign students to classrooms, the groups may differ in other ways that affect the outcome. A randomized controlled trial would require random assignment.

Question 17Unverified - official content outline not available (placeholder domain pending source)

A writer cites a 2005 report to support a claim about current remote-work legislation in 2024. Which source-evaluation criterion is most directly violated?

  1. Authority
  2. Purpose
  3. Accuracy
  4. Currency Correct answer.

Explanation

Currency concerns how up-to-date a source is for the specific claim being made. Legislation and workplace practices can change quickly, so a 2005 report may not reflect the current legal situation. Authority and accuracy might also matter, but the date is the most direct problem here.

Question 18Unverified - official content outline not available (placeholder domain pending source)

What is the main purpose of a PRISMA flow diagram in a systematic review?

  1. To present the statistical effect sizes of the included studies.
  2. To show the theoretical framework guiding the review.
  3. To list the authors' conflicts of interest and funding sources.
  4. To document record identification, screening, exclusion, and inclusion. Correct answer.

Explanation

A PRISMA flow diagram records the numbers of records identified, screened, assessed for eligibility, and included in the review, along with reasons for exclusion. This transparency helps readers judge the review's rigor and reproducibility. It does not display effect sizes or funding details.

Question 19Unverified - official content outline not available (placeholder domain pending source)

A study reports a 95% confidence interval for a mean difference of [−0.4, 1.2]. What is the most appropriate interpretation?

  1. The result proves that the intervention has no effect in the population.
  2. There is a 95% probability that the true population effect is exactly equal to positive 0.4 units.
  3. The data are compatible with effects from a small decrease to a moderate increase, including zero. Correct answer.
  4. The sample mean difference is outside the interval with 95% confidence.

Explanation

A confidence interval gives a range of plausible values for the population effect, and values inside the interval are compatible with the data at the stated confidence level. Because zero lies within this interval, the data do not rule out no effect. The interval does not assign a 95% probability to any single value such as 0.4.

Question 20Unverified - official content outline not available (placeholder domain pending source)

A qualitative researcher collects data through interviews, observations, and documents to examine the same phenomenon. Which quality criterion does this strategy primarily strengthen?

  1. Triangulation Correct answer.
  2. Statistical power
  3. Internal consistency reliability
  4. Construct validity of a survey scale

Explanation

Triangulation involves using multiple data sources, methods, or investigators to examine the same phenomenon. Converging evidence from interviews, observations, and documents can strengthen the credibility of qualitative findings. It does not increase statistical power, which applies to quantitative hypothesis tests.

Question 21Unverified - official content outline not available (placeholder domain pending source)

A researcher manipulates how many hours participants sleep and then measures their reaction time. Which variable is the independent variable?

  1. Sleep duration Correct answer.
  2. Participant age
  3. Time of day
  4. Reaction time

Explanation

The independent variable is the factor the researcher manipulates, which here is the amount of sleep. Reaction time is the dependent variable because it is measured as an outcome. Age and time of day are not manipulated in the described design.

Question 22Unverified - official content outline not available (placeholder domain pending source)

A university wants a sample that reflects the proportion of first-year, second-year, third-year, and fourth-year students. Which sampling method best achieves this?

  1. Purposive sampling
  2. Convenience sampling
  3. Stratified sampling Correct answer.
  4. Snowball sampling

Explanation

Stratified sampling divides the population into relevant subgroups, such as year of study, and then samples from each stratum, often in proportion to its size. This makes the sample reflect the population's composition more closely than convenience or snowball methods.

Question 23Unverified - official content outline not available (placeholder domain pending source)

A team administers the same 20-item scale to the same participants two weeks apart and correlates the scores. Which property are they assessing?

  1. Construct validity
  2. Inter-rater reliability
  3. Test-retest reliability Correct answer.
  4. Content validity

Explanation

Test-retest reliability concerns the stability of scores when the same measure is administered to the same people on two occasions. A high correlation between the two administrations suggests the scale yields consistent results over a short interval.

Question 24Unverified - official content outline not available (placeholder domain pending source)

A researcher tracks the same group of graduates' salaries annually for ten years. Which design is this?

  1. Cross-sectional study
  2. Quasi-experimental study
  3. Case-control study
  4. Longitudinal study Correct answer.

Explanation

A longitudinal design follows the same participants and measures the same variables repeatedly over an extended period. Tracking graduates' salaries annually for ten years fits that definition because it observes change within the same cohort.

Question 25Unverified - official content outline not available (placeholder domain pending source)

A data set of household incomes contains one extremely high value. Which measure of central tendency is most resistant to that outlier?

  1. Median Correct answer.
  2. Mean
  3. Standard deviation
  4. Range

Explanation

The median depends on the rank position of the middle value, so an extreme income changes it little or not at all. The mean uses every value and is pulled upward by a very high income, making it less resistant to outliers.

Question 26Unverified - official content outline not available (placeholder domain pending source)

What is the main purpose of a literature review in a research report?

  1. To report the author's new data
  2. To substitute for a detailed methods section
  3. To provide an exhaustive list of all sources ever read by the author
  4. To synthesize and evaluate prior research Correct answer.

Explanation

A literature review synthesizes prior scholarship, identifies patterns and gaps, and evaluates the quality of existing evidence. It is not a place for reporting the author's own new data, which belongs in the results section.

Question 27Unverified - official content outline not available (placeholder domain pending source)

A researcher owns stock in a company whose product she evaluates in a published study. What is the most appropriate action?

  1. Disclose the financial interest Correct answer.
  2. Sell the stock immediately after publication
  3. Add a colleague as a coauthor
  4. Omit the stock ownership because it is a private matter

Explanation

Financial interests that could influence a study should be disclosed so readers, editors, and reviewers can judge possible bias. Disclosure is the standard response; hiding the interest or changing authorship does not remove the conflict.

Question 28Unverified - official content outline not available (placeholder domain pending source)

A study defines "heavy social media use" as more than three hours per day on named platforms. What is this definition called?

  1. A testable hypothesis
  2. A complete sampling frame
  3. An operational definition Correct answer.
  4. A broad conceptual framework

Explanation

An operational definition specifies exactly how a concept will be measured or observed in a particular study, such as a cutoff of more than three hours per day on named platforms. It turns an abstract idea into concrete, replicable procedures.

Question 29Unverified - official content outline not available (placeholder domain pending source)

A researcher tests 20 independent hypotheses at α = .05 and reports the one significant result without adjustment. What is the main concern?

  1. The study cannot have a null hypothesis
  2. False-positive risk is inflated Correct answer.
  3. The sample size is necessarily too small
  4. The effect size must be exactly zero

Explanation

Testing many hypotheses at the .05 level raises the familywise Type I error rate, so the chance of at least one false positive becomes much greater than 5%. Researchers often adjust alpha or use a correction method to control this inflation.

Question 30Unverified - official content outline not available (placeholder domain pending source)

A city-level analysis shows neighborhoods with more parks have lower obesity rates. A reporter concludes that each person who uses a park will lose weight. Which error is most evident?

  1. Test-retest failure
  2. Sampling frame error
  3. Ecological fallacy Correct answer.
  4. Demand characteristic

Explanation

The ecological fallacy occurs when an association observed at the group level is assumed to hold for individuals. Neighborhood-level park access and obesity rates do not show that any particular park user will lose weight.

Question 31Unverified - official content outline not available (placeholder domain pending source)

What is the primary purpose of peer review before a manuscript is published?

  1. To rewrite the manuscript so that it matches the journal's house style
  2. To confirm that the authors have obtained a patent for their findings
  3. To evaluate the manuscript's quality, validity, and significance Correct answer.
  4. To verify that every statistical calculation in the study is correct

Explanation

Peer review is a quality-control process in which independent experts evaluate a manuscript's methods, analysis, and contribution before publication. It helps editors decide whether a paper is suitable, but it does not certify every calculation or perform copyediting.

Question 32Unverified - official content outline not available (placeholder domain pending source)

A researcher reuses large portions of text from her own previously published article without citation in a new paper. This practice is best described as:

  1. Peer review
  2. Self-plagiarism Correct answer.
  3. Open-access publishing
  4. Whistleblowing

Explanation

Self-plagiarism involves reusing one's own previously published or submitted work without attribution or disclosure, which can mislead readers and violate publication agreements. It is distinct from whistleblowing, open-access publishing, and peer review.

Question 33Unverified - official content outline not available (placeholder domain pending source)

Which statement is a testable research hypothesis?

  1. Students sleeping seven or more hours recall more words than those sleeping under five. Correct answer.
  2. Why do college students delay starting their assignments?
  3. Sleep is an important area that deserves considerably more research funding and public attention.
  4. Procrastination affects many people in modern society.

Explanation

A testable hypothesis states a predicted relationship between variables that can be observed and potentially falsified. The sleep-and-recall statement makes a specific comparison, whereas the other options are a question, a vague value claim, or a broad generalization.

Question 34Unverified - official content outline not available (placeholder domain pending source)

A researcher wants to survey all registered nurses in a province. She obtains a list of nurses from the provincial licensing body, but the list excludes nurses who are retired or working outside the province. The list is best described as:

  1. The sample
  2. The response rate
  3. The sampling frame Correct answer.
  4. The target population

Explanation

The sampling frame is the operational list from which participants are selected; it may under-cover or over-cover parts of the target population. The target population is the entire group of interest, the sample is the subset actually studied, and response rate is the proportion who participate.

Question 35Unverified - official content outline not available (placeholder domain pending source)

A study finds that people who carry umbrellas are more likely to get wet than people who do not. Which explanation best illustrates a confounding variable?

  1. Rain increases both umbrella carrying and getting wet. Correct answer.
  2. Getting wet causes people to go out and buy new umbrellas.
  3. People who dislike rain never leave home.
  4. Umbrellas cause people to seek out rain.

Explanation

A confounder is a third variable that influences both the proposed cause and the outcome, producing a spurious association. Rain explains both carrying umbrellas and getting wet, so umbrella carrying is not the cause.

Question 36Unverified - official content outline not available (placeholder domain pending source)

A researcher concludes that a new drug has no effect when in fact it does have an effect. This decision is:

  1. A Type II error Correct answer.
  2. A standard deviation
  3. A correct rejection
  4. A Type I error

Explanation

A Type II error occurs when a researcher fails to reject a false null hypothesis, meaning a real effect is missed. A Type I error is the opposite: rejecting a true null hypothesis. The scenario describes concluding no effect when one exists.

Question 37Unverified - official content outline not available (placeholder domain pending source)

A laboratory experiment uses a highly controlled sample of 40 college students to test a memory intervention. The main threat to generalizing the results to older adults is:

  1. High test-retest reliability
  2. High inter-rater reliability
  3. Low external validity Correct answer.
  4. Low internal validity

Explanation

External validity refers to how well findings generalize to other populations, settings, and times. A narrow sample of college students may produce results that do not apply to older adults, even if the experiment is internally sound. Reliability concerns consistency, not generalizability.

Question 38Unverified - official content outline not available (placeholder domain pending source)

A qualitative researcher conducting interviews notices that new interviews no longer produce new themes. This point is called:

  1. Statistical power
  2. Randomization
  3. Data saturation Correct answer.
  4. Attrition

Explanation

Data saturation is reached when additional interviews or observations yield no new themes or insights, indicating that further data collection is unlikely to change the analysis. It is a key sampling consideration in qualitative research. Statistical power, randomization, and attrition are quantitative or design concepts.

Question 39Unverified - official content outline not available (placeholder domain pending source)

Two studies test the same intervention. Study A reports a statistically significant but very small effect; Study B reports a non-significant but large effect with a wide confidence interval. Which conclusion is most appropriate?

  1. Study A proves the intervention is practically important simply because its p value is below .05.
  2. Significance and practical importance differ; effect size and confidence intervals matter. Correct answer.
  3. Study B proves there is no effect because it was not significant.
  4. The study with the larger sample is always the more accurate one.

Explanation

A p-value indicates how compatible the data are with a null hypothesis; it does not measure the size or practical value of an effect. Effect sizes and confidence intervals show magnitude and precision, and a non-significant result may reflect low power rather than no effect. Sample size alone does not ensure accuracy.

Question 40Unverified - official content outline not available (placeholder domain pending source)

A research team publicly archives its hypotheses, sampling plan, and analysis code before collecting data. This practice primarily aims to:

  1. Reduce questionable research practices such as selective reporting Correct answer.
  2. Guarantee that the study will be ethically approved
  3. Increase the likelihood of obtaining a statistically significant result
  4. Replace the need for peer review

Explanation

Preregistration publicly records hypotheses, methods, and analysis plans before data collection, which increases transparency and limits selective reporting or post hoc analysis changes. It does not guarantee significance, ethical approval, or replace peer review.

Question 41Unverified - official content outline not available (placeholder domain pending source)

A researcher uses a lottery to decide whether each participant is placed in the treatment group or the control group. What is this procedure called?

  1. Stratified sampling
  2. Matching
  3. Random sampling
  4. Random assignment Correct answer.

Explanation

Random assignment uses a chance procedure to place participants into conditions. It helps distribute participant characteristics evenly across groups, which strengthens causal inference. Random sampling instead concerns how participants are selected from a population.

Question 42Unverified - official content outline not available (placeholder domain pending source)

Which element is essential to informed consent in research with human participants?

  1. An explanation of procedures, risks, and voluntary participation Correct answer.
  2. A requirement that participants give up the right to withdraw
  3. A guarantee that every participant will receive the active treatment
  4. A promise that all results will remain anonymous in every case

Explanation

Informed consent requires that prospective participants receive understandable information about the study's procedures and risks. They must also know that participation is voluntary and that they may withdraw. Consent should be documented without coercing participants.

Question 43Unverified - official content outline not available (placeholder domain pending source)

Which level of measurement has a true zero point and supports statements about ratios, such as 'twice as much'?

  1. Nominal
  2. Ordinal
  3. Ratio Correct answer.
  4. Interval

Explanation

A ratio scale has equal intervals and a true zero, so ratios of values are meaningful. Weight and reaction time are examples. Interval scales have equal intervals but no true zero, so ratio statements are not valid.

Question 44Unverified - official content outline not available (placeholder domain pending source)

A company evaluates a new training program over six months. During the same period, a widely publicized industry campaign promotes the same skills. Improvement in employees' scores may reflect the campaign rather than the training. Which threat to internal validity is most relevant?

  1. History Correct answer.
  2. Maturation
  3. Testing effect
  4. Instrumentation

Explanation

A history threat occurs when an external event occurring during the study changes participants and could explain the outcome. The public campaign is such an event. Maturation, testing, and instrumentation refer to changes within participants, repeated measurement, and measurement tools, respectively.

Question 45Unverified - official content outline not available (placeholder domain pending source)

A researcher reports p = .03 for a test of a null hypothesis. Which interpretation is most appropriate?

  1. There is a 3% probability that the null hypothesis is actually true in the population
  2. There is a 3% probability that the observed result was produced by random chance alone
  3. The alternative hypothesis has a 97% probability of being true given these data
  4. The chance of data this extreme, assuming the null is true, is about 3% Correct answer.

Explanation

A p-value is the probability of obtaining a test statistic at least as extreme as the observed one, assuming the null hypothesis is true. It is not the probability that the null is true, nor the probability that chance caused the result. It also does not give the probability that the alternative is true.

Question 46Unverified - official content outline not available (placeholder domain pending source)

A 95% confidence interval for a mean difference is [2.1, 5.7]. Which statement best describes the interval?

  1. Across repeated samples, about 95% of intervals built this way would contain the true difference Correct answer.
  2. There is a 95% probability that the true population mean difference lies somewhere between 2.1 and 5.7
  3. About 95% of the individual sample means would fall between 2.1 and 5.7
  4. About 95% of participants would show a mean difference between 2.1 and 5.7

Explanation

The confidence interval procedure has a stated long-run coverage rate. In repeated sampling, 95% of intervals constructed in this way would capture the true parameter. A single realized interval either contains the parameter or does not, so one cannot assign a 95% probability to this specific interval under frequentist reasoning.

Question 47Unverified - official content outline not available (placeholder domain pending source)

A researcher compares two existing classrooms that already use different teaching methods. Students cannot be reassigned, so the researcher measures outcomes in both classrooms. Which design is this?

  1. True experimental design
  2. Quasi-experiment Correct answer.
  3. Correlational design
  4. Case study design

Explanation

A quasi-experimental design compares groups that differ on an intervention or condition without random assignment. Because the classrooms already exist, the researcher lacks random assignment and causal inference is weaker. A true experiment would require random assignment to conditions.

Question 48Unverified - official content outline not available (placeholder domain pending source)

What is the main purpose of debriefing participants after a study?

  1. To explain the purpose and address deception or concerns Correct answer.
  2. To guarantee that their individual data remain confidential
  3. To obtain their consent before data collection begins
  4. To provide payment for their time and expenses

Explanation

Debriefing occurs after participation and gives participants accurate information about the study's aims and procedures. If deception was used, the researcher explains why and corrects any misconceptions. Debriefing also gives participants a chance to ask questions and raise concerns.

Question 49Unverified - official content outline not available (placeholder domain pending source)

A researcher plans a study with a small expected effect and wants to increase statistical power while keeping the alpha level fixed. Which change is most directly effective?

  1. Reduce the alpha level to .01
  2. Increase the sample size Correct answer.
  3. Increase the variability of the outcome
  4. Decrease the effect size

Explanation

Power is the probability of rejecting the null when a specified alternative is true. Increasing sample size reduces standard error, which generally increases power for a given effect and alpha. Decreasing effect size, increasing variability, or lowering alpha would tend to reduce power.

Question 50Unverified - official content outline not available (placeholder domain pending source)

A meta-analysis finds a small overall effect, but a funnel plot shows that small studies with null results are missing. Which bias is most likely?

  1. Measurement bias
  2. Selection bias
  3. Attrition bias
  4. Publication bias Correct answer.

Explanation

Publication bias occurs when studies with statistically significant or favorable results are more likely to be published and included in a meta-analysis. Missing small null studies can make the pooled effect look larger than it is. A funnel plot is commonly used to inspect this pattern.