I85PREP
⌘ K
OAE Integrated Science study materials
OAE Integrated Science study resources

OAE Integrated Science practice questions

One question at a time. Build your OAE Integrated Science understanding.

First 50 of 200 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 1Nature of Science

A scientist writes a hypothesis before beginning an experiment. Which statement best describes the role of a hypothesis in scientific inquiry?

  1. It is a personal opinion that cannot be examined
  2. It is a final conclusion drawn after data analysis
  3. It is a testable prediction that can be supported or refuted by evidence Correct answer.
  4. It is a proven fact that guides the design of the experiment

Explanation

A hypothesis is a proposed, testable explanation or prediction that must be evaluated against empirical evidence. It is not a proven fact, a conclusion, or an untestable opinion, so it is provisional until data support or refute it.

Question 2Nature of Science

In a controlled experiment testing how fertilizer affects plant height, which is the independent variable?

  1. The type of soil used
  2. The amount of water given
  3. The height of the plants
  4. The amount of fertilizer applied Correct answer.

Explanation

The independent variable is the factor the experimenter deliberately changes, which here is the amount of fertilizer. Plant height is the dependent variable, while soil type and water are held constant as controlled variables.

Question 3Nature of Science

A student measures the same metal block five times and obtains values that cluster tightly together but differ from the accepted value by a consistent amount. How should this data set be described?

  1. Both accurate and precise
  2. Neither accurate nor precise
  3. Precise but not accurate Correct answer.
  4. Accurate but not precise

Explanation

Precision refers to how closely repeated measurements agree with one another, while accuracy refers to closeness to the true value. Tight clustering shows high precision, but the consistent offset from the accepted value shows low accuracy.

Question 4Nature of Science

Which of the following best characterizes a scientific law?

  1. A single observation recorded during one experiment
  2. A personal belief held by a researcher
  3. A statement describing a consistent relationship or pattern observed in nature Correct answer.
  4. A tentative guess that has not yet been tested

Explanation

A scientific law describes a consistent, repeatable relationship observed in nature, often expressed mathematically. It describes what happens rather than explaining why, which distinguishes it from a theory and from an untested guess.

Question 5Nature of Science

A researcher reports results that other scientists cannot reproduce when repeating the procedure. What is the most appropriate scientific response?

  1. Treat the findings as uncertain and investigate possible sources of the discrepancy Correct answer.
  2. Accept the original results because they were published first
  3. Reject the original results as fraudulent without further review
  4. Ignore the replication attempt because it was performed by a different laboratory

Explanation

Reproducibility is a cornerstone of science, so failure to replicate signals that the findings are uncertain and warrant investigation. The appropriate response is to examine methodology, conditions, and possible errors rather than to accept or condemn prematurely.

Question 6Nature of Science

Which sequence correctly represents the general order of steps in a scientific investigation?

  1. Analyze data, form a hypothesis, ask a question, draw conclusions
  2. Ask a question, form a hypothesis, conduct an experiment, analyze data Correct answer.
  3. Conduct an experiment, ask a question, analyze data, form a hypothesis
  4. Form a hypothesis, draw conclusions, ask a question, conduct an experiment

Explanation

Scientific investigations typically begin with a question, proceed to a testable hypothesis, then gather data through experimentation or observation, and finally analyze that data. Conclusions follow analysis, not precede data collection.

Question 7Nature of Science

A scientist repeats an experiment many times with large sample sizes. What is the primary purpose of this practice?

  1. To reduce the influence of random variation on the results Correct answer.
  2. To guarantee that the hypothesis is correct
  3. To make the experiment more difficult to replicate
  4. To eliminate the need for a control group

Explanation

Replication and larger samples reduce the effect of random variation, increasing confidence that observed patterns are real. They do not guarantee a correct hypothesis or replace the need for controls.

Question 8Nature of Science

Which statement best distinguishes a scientific theory from a hypothesis?

  1. A theory is a broad, well-supported explanation, while a hypothesis is a specific testable prediction Correct answer.
  2. A theory is an untested guess, while a hypothesis is a proven fact
  3. A theory is a personal opinion, while a hypothesis is a measurement
  4. A theory and a hypothesis are identical in scientific usage

Explanation

In science, a theory is a broad explanation supported by extensive evidence, whereas a hypothesis is a narrower testable prediction. The everyday meaning of theory as a guess does not match its scientific meaning.

Question 9Nature of Science

A scientist measures the boiling point of a liquid and reports 78.4 degrees Celsius. The accepted value is 78.4 degrees Celsius. Which conclusion about the measurement is most defensible?

  1. The measurement must have been repeated many times
  2. The measurement is accurate for the reported value Correct answer.
  3. The measurement proves the liquid is pure
  4. The measurement is precise but inaccurate

Explanation

Accuracy describes closeness to the accepted or true value, and a reported value matching the accepted value is accurate. A single accurate measurement does not by itself establish precision across trials or prove purity.

Question 10Nature of Science

Two groups of students test a stain remover. Group A uses cloth from one manufacturer; Group B uses cloth from a different manufacturer. The results differ. What is the most significant flaw in this design?

  1. The sample size is too large
  2. The experiment lacks a dependent variable
  3. More than one variable differs between the groups Correct answer.
  4. The hypothesis was stated too broadly

Explanation

A controlled experiment should differ between groups in only the independent variable. Using cloth from different manufacturers introduces a confounding variable that could explain the differing results.

Question 11Nature of Science

A graph shows that as temperature increases, the solubility of a solid in water also increases. Which statement correctly interprets this relationship?

  1. Solubility is the independent variable
  2. The data prove that temperature alone determines solubility
  3. Temperature causes solubility to decrease
  4. Temperature and solubility are positively correlated in this data set Correct answer.

Explanation

When both variables increase together, the relationship is a positive correlation. Correlation describes the observed pattern, but proving that temperature alone determines solubility would require ruling out other variables.

Question 12Nature of Science

A scientist wants to determine whether a new drug lowers blood pressure. Which design best supports a causal conclusion?

  1. Randomly assigning participants to drug or placebo groups and comparing blood pressure changes Correct answer.
  2. Measuring blood pressure once in a single patient after treatment
  3. Observing patients who already take the drug and comparing them with the general public
  4. Surveying patients about whether they believe the drug works

Explanation

Random assignment to treatment and placebo groups with a controlled comparison supports causal inference by balancing confounding factors. Observational comparisons, surveys, and single measurements cannot isolate the drug's effect as strongly.

Question 13Nature of Science

During peer review, reviewers identify that a study's conclusions exceed what the data can support. What does this illustrate about the scientific process?

  1. Scientific claims are evaluated critically by the community before acceptance Correct answer.
  2. Peer review guarantees that published findings are correct
  3. Conclusions do not need to follow from evidence
  4. Scientists never make errors in reasoning

Explanation

Peer review is a critical evaluation by the scientific community that helps identify weaknesses before publication. It improves quality but does not guarantee correctness, and conclusions must still follow from evidence.

Question 14Nature of Science

A student claims that because a coin landed heads five times in a row, tails is now more likely on the next toss. Which reasoning error does this illustrate?

  1. Using an incorrect unit of measurement
  2. Assuming that independent events are influenced by past outcomes Correct answer.
  3. Applying a controlled experimental design
  4. Confusing correlation with causation

Explanation

Each coin toss is an independent event, so past outcomes do not change the probability of the next toss. The gambler's fallacy arises from assuming that independent events are influenced by previous results.

Question 15Nature of Science

Which action best demonstrates the principle that scientific knowledge is open to revision?

  1. Revising a model when new, well-supported evidence conflicts with it Correct answer.
  2. Treating a textbook as the final authority on all questions
  3. Accepting a claim because it is popular
  4. Refusing to consider new evidence that contradicts an accepted model

Explanation

Scientific knowledge is provisional and is revised when new evidence convincingly conflicts with existing models. Refusing evidence, relying on popularity, or treating texts as final authorities contradicts this principle.

Question 16Nature of Science

A researcher measures the mass of a sample three times and obtains 10.1 g, 10.2 g, and 10.1 g. The accepted value is 10.1 g. Which statement is best supported?

  1. The measurements are both precise and accurate Correct answer.
  2. The measurements are neither precise nor accurate
  3. The measurements are accurate but imprecise
  4. The measurements are precise but inaccurate

Explanation

The values cluster closely together, indicating high precision, and they center on the accepted value of 10.1 g, indicating high accuracy. Both qualities are therefore present in this data set.

Question 17Nature of Science

In an experiment, a control group is included primarily to do which of the following?

  1. Increase the total number of participants
  2. Introduce a second independent variable
  3. Provide a baseline for comparison against the experimental group Correct answer.
  4. Ensure that the hypothesis is correct

Explanation

A control group is held constant or untreated so that its results provide a baseline against which the experimental group's results can be compared. It does not introduce new variables or guarantee a correct hypothesis.

Question 18Nature of Science

A news article reports that people who eat breakfast daily tend to weigh less. Which additional consideration is most important before concluding that eating breakfast causes weight loss?

  1. Whether the article was long enough
  2. Whether the people surveyed enjoyed breakfast
  3. Whether weight was measured in kilograms or pounds
  4. Whether other factors such as activity level were accounted for Correct answer.

Explanation

Observational associations can be explained by confounding factors, so researchers must account for variables such as activity level before inferring causation. Units and article length do not affect the validity of the causal inference.

Question 19Nature of Science

A scientific model of a complex system is useful primarily because it does which of the following?

  1. Simplifies the system to highlight key relationships and make predictions Correct answer.
  2. Proves that the system cannot change
  3. Reproduces every detail of the real system exactly
  4. Replaces the need for empirical evidence

Explanation

Models simplify complex systems so that key relationships can be examined and predictions tested. They are approximations rather than exact copies and do not replace empirical evidence.

Question 20Nature of Science

A scientist formulates a hypothesis that cannot possibly be shown false by any observation. How does this affect the hypothesis's scientific value?

  1. It weakens the hypothesis because it is not falsifiable Correct answer.
  2. It converts the hypothesis into a scientific law
  3. It has no effect because falsifiability is irrelevant to science
  4. It strengthens the hypothesis by making it universally true

Explanation

A scientifically useful hypothesis must be falsifiable, meaning some possible observation could show it to be wrong. An unfalsifiable claim cannot be tested against evidence and therefore has limited scientific value.

Question 21Nature of Science

A drug trial finds a statistically significant difference between treatment and placebo groups, but the effect size is very small. What is the most careful interpretation?

  1. The difference must be due to chance
  2. Statistical significance means the effect size is irrelevant
  3. The treatment is proven to be highly effective
  4. The difference is real but may have limited practical importance Correct answer.

Explanation

Statistical significance indicates that an observed difference is unlikely to be due to chance alone, but it says nothing about the magnitude of the effect. A small effect size can be statistically significant yet of limited practical importance.

Question 22Nature of Science

A researcher uses a sample drawn only from volunteers at a single gym to study exercise habits of the general population. Which limitation is most serious?

  1. The sample may not be representative of the general population Correct answer.
  2. The measurements were taken in metric units
  3. The hypothesis was stated before data collection
  4. The study used too many variables

Explanation

Volunteers from one gym are likely to differ systematically from the general population, producing sampling bias that limits generalizability. Units, variable count, and hypothesis timing are not the central flaw here.

Question 23Nature of Science

Two hypotheses both explain the same observations, but one makes additional predictions that can be tested while the other makes none. Which principle favors the testable hypothesis?

  1. The principle that older hypotheses are always superior
  2. The principle that untestable claims are automatically correct
  3. The principle that hypotheses should generate testable predictions Correct answer.
  4. The principle that simpler explanations are preferred regardless of testability

Explanation

A core norm of science is that hypotheses should yield testable predictions that allow them to be evaluated against evidence. A hypothesis making no testable predictions cannot be distinguished from alternatives through observation.

Question 24Nature of Science

A scientist publishes a result and later finds that a calibration error affected all measurements by the same percentage. What is the most appropriate response?

  1. Assume the error cancels out across all measurements
  2. Conceal the error to protect the original conclusion
  3. Reclassify the study as a law rather than an experiment
  4. Publicly correct the record and reassess the conclusions in light of the error Correct answer.

Explanation

Scientific integrity requires transparency, so a discovered systematic error should be disclosed and its effect on the conclusions reassessed. Concealing errors, assuming cancellation, or relabeling the work violates scientific norms.

Question 25Nature of Science

A student argues that because a hypothesis has survived many tests without being refuted, it is now a proven fact. Which critique of this reasoning is most accurate?

  1. A hypothesis becomes a fact as soon as it is published
  2. Only a single successful test is needed to establish a fact
  3. Surviving tests supports the hypothesis but does not make it a proven fact Correct answer.
  4. Repeated testing is irrelevant to the status of a hypothesis

Explanation

Repeated successful testing increases confidence in a hypothesis, but scientific knowledge remains provisional and open to revision. No amount of testing converts a hypothesis into an absolute, unchangeable fact.

Question 26Nature of Science

In an investigation of how light intensity affects the rate of photosynthesis in pondweed, which variable is the independent variable?

  1. The temperature of the water bath
  2. The distance of the lamp from the plant Correct answer.
  3. The species of pondweed used
  4. The number of oxygen bubbles produced per minute

Explanation

The independent variable is the factor the investigator deliberately changes, here the distance of the lamp, which sets the light intensity. The bubble count is the dependent variable because it is measured as the outcome, while temperature and species are controlled.

Question 27Nature of Science

A student records the length of a metal rod as 12.34 cm using a ruler marked in millimetres. Which statement about this measurement is most accurate?

  1. The measurement cannot be used because it lacks an uncertainty statement.
  2. The value is exact because it includes two decimal places.
  3. The recorded value implies precision beyond what the ruler's markings support. Correct answer.
  4. The measurement is invalid because rulers cannot measure length.

Explanation

A ruler marked in millimetres allows estimation to about one-tenth of a millimetre, so reporting two decimal places in centimetres overstates the instrument's resolution. Significant figures should reflect the precision of the measuring device.

Question 28Nature of Science

Which statement best describes the role of a hypothesis in scientific inquiry?

  1. It is a proposed, testable explanation that generates predictions about observations. Correct answer.
  2. It is a personal opinion that cannot be examined through evidence.
  3. It is a final conclusion drawn after data collection is complete.
  4. It is a summary of previously published experimental results.

Explanation

A hypothesis is a tentative, testable explanation that leads to predictions which can be checked against evidence. It is formulated before or during investigation and is subject to revision, not treated as a final conclusion.

Question 29Nature of Science

A class measures the mass of the same object on four balances and obtains 50.0 g, 50.1 g, 49.9 g, and 50.0 g. The accepted value is 60.0 g. Which conclusion about the measurements is best supported?

  1. They are both accurate and precise.
  2. They are accurate but not precise.
  3. They are precise but not accurate. Correct answer.
  4. They are neither accurate nor precise.

Explanation

Precision refers to how closely repeated measurements agree with one another, and these values cluster tightly, so precision is high. Accuracy refers to closeness to the accepted value, and all four values are far from 60.0 g, so accuracy is low.

Question 30Nature of Science

Which practice most directly supports the reproducibility of a scientific investigation?

  1. Reporting only the trials that produced the expected outcome
  2. Publishing conclusions before the data are analyzed
  3. Rounding all data to a single significant figure
  4. Recording the procedures and conditions in enough detail for others to repeat them Correct answer.

Explanation

Reproducibility requires that other investigators can repeat the study and obtain comparable results, which depends on complete documentation of methods and conditions. Selective reporting, excessive rounding, and premature conclusions all undermine that goal.

Question 31Nature of Science

A scientist uses a model to predict coastal flooding under different sea-level scenarios. Which limitation of models is most important to communicate when sharing these predictions?

  1. Models are valid only when they produce a single outcome.
  2. Models cannot incorporate quantitative data.
  3. Models are always less useful than direct observation of every possible scenario.
  4. Models simplify real systems and carry assumptions that introduce uncertainty. Correct answer.

Explanation

Models necessarily simplify complex systems, so their assumptions and uncertainties must be disclosed alongside predictions. This does not mean models are useless; they are valuable precisely because they allow exploration of scenarios that cannot be directly observed.

Question 32Nature of Science

In a controlled experiment testing a fertilizer on plant growth, which procedure best reduces the influence of confounding variables?

  1. Applying fertilizer to the tallest plants and no fertilizer to the shortest
  2. Testing each plant in a different room with different lighting
  3. Giving all plants identical light, water, and soil except for the fertilizer treatment Correct answer.
  4. Changing the amount of water whenever growth appears slow

Explanation

Confounding variables are factors other than the independent variable that could affect the outcome, so they must be held constant. Keeping light, water, and soil identical isolates the fertilizer as the only difference between groups.

Question 33Nature of Science

Which statement best explains why scientific knowledge is described as tentative?

  1. Established laws are discarded whenever a single study is published.
  2. Scientific findings are guesses that cannot be tested.
  3. Scientists frequently disagree, so no finding can be trusted.
  4. Conclusions may be revised when new evidence or better methods become available. Correct answer.

Explanation

Tentativeness means scientific claims are open to revision in light of new evidence or improved methods, not that they are untrustworthy. Well-supported knowledge is durable but never immune to revision.

Question 34Nature of Science

A researcher wants to know whether a new study method improves exam scores. Which outcome measure best represents an operational definition of the dependent variable?

  1. The score on a standardized exam administered to both groups Correct answer.
  2. The students' general feelings of confidence about school
  3. The amount of homework students choose to complete
  4. The teacher's overall impression of student effort

Explanation

An operational definition specifies how a variable is measured in concrete terms. A standardized exam score provides a defined, quantifiable measure of the outcome, whereas impressions and feelings are vague and not consistently measurable.

Question 35Nature of Science

A team reports that a new coating increases solar panel efficiency by 2 percent with a p-value of 0.04. Which interpretation of the p-value is most appropriate?

  1. There is a 4 percent probability that the coating has no effect.
  2. The coating will improve efficiency in 96 percent of installations.
  3. Assuming no real effect, results at least this extreme would occur about 4 percent of the time by chance. Correct answer.
  4. The effect is practically important because the p-value is below 0.05.

Explanation

A p-value is the probability of obtaining results at least as extreme as those observed, assuming the null hypothesis is true. It is not the probability that the null hypothesis is true, nor a measure of practical importance or per-installation success.

Question 36Nature of Science

A scientist investigates whether a supplement affects reaction time. Participants are randomly assigned to supplement or placebo, and neither participants nor assessors know group membership. Which feature most strengthens the causal claim?

  1. Measuring reaction time with a single trial per participant
  2. Allowing participants to choose their own group
  3. Random assignment combined with blinding of participants and assessors Correct answer.
  4. Announcing group membership to assessors before testing

Explanation

Random assignment distributes confounding factors across groups, and blinding reduces expectation effects from both participants and assessors. Together these features make a causal interpretation of the difference more defensible.

Question 37Nature of Science

A study finds that students who use a tutoring app score higher on a test. Which additional factor most threatens a causal interpretation of this result?

  1. Students who chose the app may already be more motivated to study Correct answer.
  2. The app was available on multiple device types
  3. The test was administered on the same day to all students
  4. The test included both multiple-choice and short-answer items

Explanation

When participants choose their own treatment, pre-existing differences such as motivation can explain the outcome, creating a confounding variable. Random assignment is the design feature that would reduce this threat.

Question 38Nature of Science

A researcher graphs data showing a strong positive correlation between ice cream sales and drowning incidents. Which conclusion is most justified?

  1. The correlation must be due to measurement error.
  2. Drowning incidents cause increases in ice cream sales.
  3. A third variable such as warm weather may influence both, so correlation alone does not show causation. Correct answer.
  4. Eating ice cream causes drowning, so sales should be restricted.

Explanation

Correlation describes association, not causation, and a lurking variable like seasonal temperature plausibly drives both patterns. Without controlled comparison, no causal direction can be inferred from the correlation itself.

Question 39Nature of Science

During an investigation, a student's results contradict the hypothesis. Which response best reflects scientific reasoning?

  1. Adjust the data so they match the predicted outcome
  2. Discard the investigation without recording the results
  3. Record the results honestly and revise the hypothesis or consider alternative explanations Correct answer.
  4. Repeat the experiment until the expected result appears

Explanation

Unexpected results are informative and should be reported accurately; they may prompt revision of the hypothesis or suggest new explanations. Altering data or repeating until a desired outcome appears constitutes bias and misconduct.

Question 40Nature of Science

A scientist reports a measurement as 25.0 plus or minus 0.5 units. Which statement best describes what the uncertainty represents?

  1. A range within which the true value is reasonably expected to lie Correct answer.
  2. A guarantee that the true value equals 25.0 exactly
  3. The difference between the highest and lowest values in the sample
  4. The maximum value the instrument can display

Explanation

An uncertainty states a plausible range around the reported value within which the true value likely falls. It reflects limitations of the instrument and method, not a guarantee of exactness or a range of the instrument.

Question 41Nature of Science

A peer reviewer notices that a paper's conclusion about a population is based on a sample recruited entirely from one university. Which criticism is most appropriate?

  1. The sample is too small for any statistical analysis to be performed
  2. The conclusion is invalid because universities cannot host research
  3. The sample may not be representative, limiting how far the conclusions can be generalized Correct answer.
  4. The study should have avoided using a control group

Explanation

Generalizability depends on how well the sample represents the target population, and a single-university sample may differ systematically from the broader group. This is a limitation on external validity rather than a claim that no analysis is possible.

Question 42Nature of Science

Two explanations account for the same observations, but one predicts a specific outcome under a new condition while the other makes no such prediction. Which explanation is scientifically preferable and why?

  1. The one making the testable prediction, because it can be exposed to potential refutation Correct answer.
  2. Both are equally preferable because both fit the current data
  3. Neither is scientific because both are explanations
  4. The one making no prediction, because it cannot be shown wrong

Explanation

A hypothesis that generates specific, testable predictions is more scientifically useful because it can be supported or refuted by new evidence. Fitting existing observations alone does not distinguish between competing explanations.

Question 43Nature of Science

A student writes that a plant grew 5 cm because it was given more sunlight, based on one plant given sunlight and one kept in a dark closet. Which flaw most limits this conclusion?

  1. Growth should have been measured in metres instead of centimetres
  2. Only one plant per condition was used, so individual variation and other differences cannot be separated from the treatment Correct answer.
  3. The plant in the dark should have been watered more often
  4. The closet should have been kept at a different temperature

Explanation

With a single plant per condition, natural individual variation and uncontrolled differences cannot be distinguished from the effect of light. Replication with multiple plants per group is needed to support the causal claim.

Question 44Nature of Science

A scientist applies a correction to raw data before analysis. Which practice best preserves scientific integrity?

  1. Reporting corrected values as if they were raw measurements
  2. Correcting only the data points that seem unusual
  3. Applying the correction silently so readers are not confused
  4. Documenting the correction method and rationale so others can evaluate and reproduce it Correct answer.

Explanation

Transparency about data processing allows others to assess whether the correction is justified and to reproduce the analysis. Undisclosed or selective correction obscures the evidence and undermines trust.

Question 45Nature of Science

A researcher wants to compare two teaching methods across several classrooms. Which approach best reduces the chance that a classroom's existing ability level explains any difference?

  1. Randomly assigning classrooms to methods and comparing gains from pre-test to post-test Correct answer.
  2. Letting each teacher choose which method to use
  3. Assigning the highest-scoring classroom to the new method
  4. Comparing post-test scores only, without a pre-test

Explanation

Random assignment helps balance pre-existing ability across groups, and measuring gains from pre-test to post-test controls for initial differences. Together these features reduce the chance that baseline ability explains the result.

Question 46Nature of Science

A scientist claims that a new telescope design will detect a specific type of signal, but the claim is stated so vaguely that no observation could count against it. How does this affect the claim's scientific status?

  1. It is testable because it mentions a telescope
  2. It becomes a scientific law once published
  3. It is stronger because it cannot be proven wrong
  4. It is not scientifically testable as stated because no possible observation could refute it Correct answer.

Explanation

A claim must be framed so that some conceivable observation could count against it to be scientifically testable. Vagueness that excludes all possible refutation removes the claim from empirical testing until it is made specific.

Question 47Nature of Science

An investigator finds that a new fertilizer increases yield by 15 percent in a large, well-controlled field trial, with a very small p-value. A separate small trial finds a 2 percent increase with a p-value of 0.20. Which conclusion is best supported?

  1. Both trials provide equally strong evidence because both used fertilizer
  2. The p-value of 0.20 proves the fertilizer has no effect
  3. The larger trial provides stronger evidence of a real effect, while the smaller trial's result is inconclusive Correct answer.
  4. The smaller trial's result is more trustworthy because the effect is smaller

Explanation

A small p-value from a well-controlled, adequately powered trial provides stronger evidence against the null hypothesis. A nonsignificant result in a small trial is inconclusive rather than proof of no effect, since the study may lack power.

Question 48Nature of Science

A researcher measures the same quantity with two instruments. Instrument A gives values that cluster tightly but are consistently 3 units above the accepted value; instrument B gives values that scatter widely around the accepted value. Which description is correct?

  1. Both instruments are equally accurate because both were used correctly
  2. Instrument B is precise because its values average near the accepted value
  3. Instrument A is accurate but imprecise, while instrument B is precise and biased
  4. Instrument A is precise but biased, while instrument B is imprecise but essentially unbiased Correct answer.

Explanation

Precision concerns the spread of repeated measurements, so A's tight clustering reflects high precision, while its consistent offset indicates systematic bias. B's wide scatter shows low precision, but centering on the accepted value indicates little systematic bias.

Question 49Nature of Science

A published study reports a statistically significant effect, but a later large replication finds a much smaller effect. Which explanation is most consistent with good scientific practice?

  1. Replication results should be ignored when they conflict with the original
  2. The later study is wrong because larger studies are less reliable
  3. Initial estimates can be inflated by chance and publication bias, and replication refines the estimated effect size Correct answer.
  4. The original study must have been fraudulent because the effect changed

Explanation

Early significant findings, especially in small studies, can overestimate effects through chance and publication bias favoring positive results. Replication with larger samples refines estimates, and disagreement is resolved through accumulated evidence rather than assumed misconduct.

Question 50Nature of Science

A scientist uses a computer model to estimate future rainfall. The model is calibrated on historical data and produces a range of projections. Which statement best evaluates the appropriate use of these projections?

  1. They should be discarded because models cannot use historical data
  2. They should inform decisions with uncertainty acknowledged, because the model's assumptions and calibration limit certainty Correct answer.
  3. They should be treated as exact predictions because they come from a computer
  4. They should be accepted only if all projections are identical

Explanation

Model projections are valuable for decision-making when their uncertainty and assumptions are communicated honestly. Treating them as exact or rejecting them outright both misrepresent how models contribute to scientific understanding.