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HSC Science Extension practice questions

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Question 1The Foundations of Scientific Thinking

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

  1. It is a personal opinion that requires no evidence.
  2. It is a testable proposed explanation that generates predictions. Correct answer.
  3. It is a final conclusion that cannot be revised.
  4. It is an observation recorded without interpretation.

Explanation

A hypothesis is a proposed explanation framed so that it can be tested against evidence, usually by deriving predictions from it. Because it is provisional, it can be supported, refined or rejected as new data appear. This testability is what separates it from opinion or fixed conclusion.

Question 2The Foundations of Scientific Thinking

A controlled experiment is designed mainly to do which of the following?

  1. Isolate the effect of one variable by holding others constant Correct answer.
  2. Increase the sample size until results are significant
  3. Replicate the study in a different laboratory
  4. Remove all measurement error from the data

Explanation

In a controlled experiment the independent variable is manipulated while other relevant factors are held constant, so any change in the dependent variable can be attributed to that manipulation. This isolation of a single variable is the defining purpose of control. It does not by itself guarantee larger samples or eliminate measurement error.

Question 3The Foundations of Scientific Thinking

In an experiment testing fertiliser effects on plant growth, which is the independent variable?

  1. The height each plant reaches
  2. The amount of fertiliser applied Correct answer.
  3. The temperature of the greenhouse
  4. The number of plants measured

Explanation

The independent variable is the factor deliberately manipulated by the researcher, here the amount of fertiliser applied. Plant height is the dependent variable because it is measured as the response. Temperature and plant number are controlled or sample variables, not the manipulated factor.

Question 4The Foundations of Scientific Thinking

Which practice most directly improves the reliability of a scientific measurement?

  1. Describing the method in greater detail
  2. Reporting results to more decimal places
  3. Choosing a more interesting research question
  4. Repeating the measurement several times Correct answer.

Explanation

Reliability concerns consistency, so repeating measurements and averaging them reduces the influence of random variation and gives a more dependable value. Extra decimal places do not improve the underlying precision of the instrument. Detailed methods aid reproducibility but do not themselves make repeated values consistent.

Question 5The Foundations of Scientific Thinking

A scientist reads a claim that a new supplement boosts memory. Which feature of the evidence would most strengthen the claim?

  1. The claim was tested in a controlled trial with a placebo group Correct answer.
  2. The claim is supported by a testimonial from an athlete
  3. The claim is repeated by several social media accounts
  4. The claim appears on a popular health website

Explanation

A controlled trial with a placebo group allows the effect of the supplement to be separated from expectation and other influences. This design provides evidence that can be evaluated independently of personal belief. Testimonials and repetition are anecdotes or popularity, not controlled evidence.

Question 6The Foundations of Scientific Thinking

What is the main purpose of peer review before publication?

  1. To guarantee that the results will be replicated
  2. To ensure the authors are paid for their research
  3. To assess the quality and validity of the work Correct answer.
  4. To make the findings easier for the public to read

Explanation

Peer review subjects a manuscript to scrutiny by independent experts who judge the soundness of methods, analysis and interpretation. It is a quality-control filter, not a guarantee of truth. It does not promise replication, public accessibility or payment.

Question 7The Foundations of Scientific Thinking

A result is described as statistically significant. What does this most accurately mean?

  1. The result is unlikely to have arisen by chance alone under the null hypothesis Correct answer.
  2. The experiment was performed without any errors
  3. The result has been confirmed by independent replication
  4. The result is large enough to be important in practice

Explanation

Statistical significance indicates that the observed result would be unlikely if the null hypothesis were true, given the chosen threshold. It is a statement about probability under a model, not about practical importance. Nor does it certify error-free work or independent confirmation.

Question 8The Foundations of Scientific Thinking

Which example best illustrates a pseudoscientific claim?

  1. A theory that is revised when new evidence emerges
  2. A hypothesis that is later rejected after careful testing
  3. A model that makes predictions later confirmed by new data
  4. A claim that cannot be tested and is defended by dismissing all contrary evidence Correct answer.

Explanation

Pseudoscientific claims typically present themselves as scientific while remaining untestable or immune to refutation, often by dismissing contrary evidence. Genuine science invites testing and revision. Rejected hypotheses, confirmed models and revised theories are normal features of scientific practice.

Question 9The Foundations of Scientific Thinking

A student measures the boiling point of a liquid five times and obtains values tightly clustered around 82 degrees Celsius, but the accepted value is 78 degrees Celsius. Which description fits these results?

  1. Reliable but not valid Correct answer.
  2. Valid but not reliable
  3. Both reliable and valid
  4. Neither reliable nor valid

Explanation

The readings are consistent with one another, so they are reliable, but they cluster away from the accepted value, so they lack validity. Reliability concerns consistency, whereas validity concerns closeness to the true value. Systematic error can produce this pattern of high precision with poor accuracy.

Question 10The Foundations of Scientific Thinking

A researcher finds that students who eat breakfast score higher on a test. Which is the most reasonable conclusion?

  1. There is an association between breakfast and test scores Correct answer.
  2. Test scores cause students to eat breakfast
  3. No relationship exists between the variables
  4. Eating breakfast causes higher test scores

Explanation

An observational association does not by itself establish causation, because other factors such as sleep, income or study habits may influence both variables. The cautious conclusion is that an association was observed. Establishing causation would require controlled or well-designed longitudinal evidence.

Question 11The Foundations of Scientific Thinking

Why is a control group included in a clinical trial of a new drug?

  1. To provide a baseline for comparison without the active treatment Correct answer.
  2. To increase the total number of participants
  3. To test whether the drug is safe at any dose
  4. To ensure the drug is given to everyone who needs it

Explanation

A control group provides a comparison baseline, often receiving a placebo or standard treatment, so the effect of the new drug can be distinguished from other influences. Without it, changes could be attributed to expectation, natural recovery or time. Controls do not increase participant numbers or establish safety on their own.

Question 12The Foundations of Scientific Thinking

A team reports a finding with a p-value of 0.04 using a threshold of 0.05. They then repeat the analysis on many subgroups until one shows p = 0.001. What is the main concern with the subgroup result?

  1. The sample size was too small in the original study
  2. Multiple comparisons increase the chance of a false positive Correct answer.
  3. Subgroup analysis is never scientifically useful
  4. The original p-value was calculated incorrectly

Explanation

Testing many subgroups raises the probability that at least one will appear significant by chance alone, a problem of multiple comparisons. The striking subgroup p-value may therefore be an artefact of repeated testing. Adjusting for multiplicity or pre-specifying subgroups addresses this concern.

Question 13The Foundations of Scientific Thinking

Which change would most improve the validity of an experiment measuring reaction time using a stopwatch?

  1. Testing all participants in the same room
  2. Asking each participant to perform the task once
  3. Using a digital timing device that removes human reaction lag Correct answer.
  4. Recording times to three decimal places

Explanation

Validity concerns whether the measurement actually reflects the intended quantity, here true reaction time. A stopwatch includes the experimenter's own reaction lag, a systematic error, so replacing it with an automated timer improves validity. More decimal places or a single trial do not correct that systematic bias.

Question 14The Foundations of Scientific Thinking

A scientific model is best understood as which of the following?

  1. A substitute for collecting data
  2. A permanent description of reality
  3. A guess made without any evidence
  4. A simplified representation used to explain and predict Correct answer.

Explanation

Models are deliberate simplifications that capture key features of a system so that it can be explained and predictions made. They are judged by their usefulness and predictive power rather than by being exact copies of reality. Models are revised as evidence accumulates and do not replace data collection.

Question 15The Foundations of Scientific Thinking

Two researchers disagree about a claim. Which response best reflects scientific thinking?

  1. Defer to whichever view is more popular
  2. Reject the claim because it is unfamiliar
  3. Examine the evidence and methods behind each position Correct answer.
  4. Accept the claim because the senior researcher supports it

Explanation

Scientific thinking evaluates claims on the strength of evidence and the soundness of methods rather than on authority, familiarity or popularity. Examining the evidence allows disagreements to be resolved on defensible grounds. Appeals to seniority or consensus alone are not sufficient justification.

Question 16The Foundations of Scientific Thinking

A study finds a strong negative correlation between hours of television watched and exam performance. Which explanation is most consistent with this finding?

  1. The correlation must be a calculation error
  2. Exam performance determines television habits
  3. Watching television directly reduces intelligence
  4. A third factor such as study time may influence both variables Correct answer.

Explanation

A negative correlation shows that the variables move in opposite directions, but it does not identify the cause. A confounding variable such as study time could independently affect both television watching and exam performance. Inferring direct causation or dismissing the data are both unjustified.

Question 17The Foundations of Scientific Thinking

Which statement about a scientific theory is most accurate?

  1. It is a proven fact that can never change
  2. It is a tentative guess awaiting confirmation
  3. It is less reliable than a single experiment
  4. It is a well-supported explanatory framework built from repeated evidence Correct answer.

Explanation

In science a theory is a broad explanatory framework supported by extensive evidence and able to generate predictions. It is stronger than a single experiment or hypothesis, yet remains open to revision. The everyday meaning of theory as a mere guess does not apply.

Question 18The Foundations of Scientific Thinking

An experiment tests whether a fertiliser increases yield, using one field with fertiliser and an adjacent field without. Which factor most threatens the validity of the conclusion?

  1. The two fields may differ in soil quality and sunlight Correct answer.
  2. The fertiliser was applied in spring
  3. The experiment was conducted outdoors
  4. The yield was measured in kilograms

Explanation

If the two fields differ systematically in soil, light or drainage, those differences are confounded with the fertiliser treatment. Any yield difference could then be caused by the field conditions rather than the fertiliser. Randomly assigning plots within a uniform area would reduce this threat.

Question 19The Foundations of Scientific Thinking

Why do scientists prefer to publish methods in enough detail for others to repeat the study?

  1. It allows findings to be tested and confirmed independently Correct answer.
  2. It guarantees the results will be correct
  3. It removes the need for statistical analysis
  4. It prevents other scientists from criticising the work

Explanation

Detailed methods allow other researchers to repeat the study, which is how findings are independently tested and either supported or challenged. Reproducibility is central to scientific self-correction. It does not guarantee correctness or shield work from criticism, and analysis remains necessary.

Question 20The Foundations of Scientific Thinking

A newspaper reports that a chemical 'causes cancer' based on a study of 20 mice. Which criticism is most appropriate?

  1. The study should have used no control group
  2. Mice are irrelevant to all biological research
  3. The sample is small and animal results may not transfer to humans Correct answer.
  4. Newspapers should never report scientific findings

Explanation

A small sample limits the strength of any conclusion, and findings in mice require caution before being extended to humans. Responsible reporting should convey this uncertainty rather than state causation outright. Animal models remain valuable, and controls are essential rather than optional.

Question 21The Foundations of Scientific Thinking

A researcher claims an effect is real because the result had p = 0.049, just under the 0.05 threshold. Which reasoning is most sound?

  1. Statistical significance proves the effect size is large
  2. The effect is certainly real because p is below 0.05
  3. The threshold should be lowered until the result is clearly significant
  4. A result near the threshold is weak evidence and should be interpreted cautiously Correct answer.

Explanation

A p-value close to the decision threshold provides only marginal evidence, since small changes in the data could move it across the line. Sound interpretation considers effect size, confidence intervals and replication rather than treating the threshold as a sharp boundary. Significance also says nothing directly about effect size.

Question 22The Foundations of Scientific Thinking

A hypothesis is described as falsifiable. Which situation best demonstrates this property?

  1. The hypothesis is supported by every observation made
  2. The hypothesis is accepted by most scientists
  3. The hypothesis cannot be tested with current technology
  4. The hypothesis specifies an observation that would show it to be false Correct answer.

Explanation

Falsifiability means the hypothesis rules out certain observations, so that specific evidence could show it to be wrong. This makes it genuinely testable. Universal support, majority acceptance or current technological limits do not establish falsifiability.

Question 23The Foundations of Scientific Thinking

Two studies investigate the same question. Study A uses a large random sample but measures the outcome indirectly; Study B uses a small convenience sample but measures the outcome directly and precisely. Which evaluation is most defensible?

  1. Both studies are worthless because neither is perfect
  2. Study B is superior because its measurement is direct
  3. Study A is superior because its sample is larger
  4. Each study has strengths and weaknesses that affect different aspects of validity Correct answer.

Explanation

Study A has stronger external validity through random sampling but weaker construct validity from indirect measurement, while Study B shows the reverse pattern. Judging overall quality requires weighing these trade-offs against the research aim. Neither study is simply superior or worthless.

Question 24The Foundations of Scientific Thinking

A phenomenon is observed that current theory cannot explain. What is the most scientifically appropriate response?

  1. Modify the observation until it fits the theory
  2. Treat the anomaly as a reason to investigate and possibly revise the theory Correct answer.
  3. Ignore the anomaly because the theory is well established
  4. Declare the theory false immediately

Explanation

Anomalies that resist explanation can motivate investigation and, if robust, drive revision of accepted theory. Science treats well-supported theory as provisional rather than absolute. Altering data to fit expectations is misconduct, while ignoring or instantly discarding theory are both extremes.

Question 25The Foundations of Scientific Thinking

A meta-analysis combines many studies and finds a small overall effect, but several included studies had publication bias. How should the result be interpreted?

  1. Publication bias improves the accuracy of a meta-analysis
  2. The overall effect is likely overstated and should be treated cautiously Correct answer.
  3. The small effect proves there is no real effect
  4. The meta-analysis is invalid and should be discarded entirely

Explanation

Publication bias means studies with significant or positive results are more likely to be published, so a meta-analysis drawing on the literature may overestimate the true effect. The finding should therefore be interpreted cautiously, ideally with bias-adjusted methods. Bias does not make the analysis worthless, nor does a small effect mean no effect.

Question 26The Foundations of Scientific Thinking

Which practice most directly allows other scientists to evaluate the reliability of a reported measurement?

  1. Presenting the result at a large international conference
  2. Reporting the measurement together with its estimated uncertainty Correct answer.
  3. Publishing the result in a journal with a high impact factor
  4. Repeating the experiment until the same number appears twice

Explanation

A measurement is only meaningful when accompanied by an estimate of its uncertainty, because every instrument and procedure introduces error. Reporting uncertainty lets readers judge how much confidence the value deserves and whether differences between results are meaningful.

Question 27The Foundations of Scientific Thinking

A scientist writes that a hypothesis must be testable against evidence. Which feature of the hypothesis does this requirement most directly support?

  1. Its capacity to generate predictions that could fail Correct answer.
  2. Its consistency with the researcher's earlier publications
  3. Its approval by a funding committee before the study
  4. Its ability to be expressed in mathematical notation

Explanation

Testability means the hypothesis yields predictions that observations could contradict, which is what allows evidence to discriminate between competing ideas. A claim that cannot fail under any conceivable observation cannot be tested scientifically.

Question 28The Foundations of Scientific Thinking

In scientific reasoning, what distinguishes an observation from an inference?

  1. Observations are always numerical, whereas inferences are always verbal
  2. Observations are provisional, whereas inferences are permanent conclusions
  3. Observations are direct records of evidence, whereas inferences are interpretations drawn from evidence Correct answer.
  4. Observations are made by instruments, whereas inferences are made by people

Explanation

Observations record what was detected through senses or instruments, while inferences are conclusions reasoned from those records. The same observation can support different inferences, which is why the distinction matters when evaluating claims.

Question 29The Foundations of Scientific Thinking

Which statement best describes the role of a hypothesis in an investigation?

  1. It is a proposed explanation that guides what data will be collected Correct answer.
  2. It guarantees the outcome the researcher expects to record
  3. It replaces the need for a control condition in the design
  4. It is a summary written after the data have been fully analysed

Explanation

A hypothesis is a tentative explanation or prediction that directs the design of an investigation and specifies what evidence is relevant. It is formulated before data collection and is later evaluated against the results.

Question 30The Foundations of Scientific Thinking

Why is random assignment of participants important in an experiment comparing two treatments?

  1. It increases the total number of participants available
  2. It removes the need to measure outcomes objectively
  3. It balances known and unknown confounding factors across the groups Correct answer.
  4. It ensures that every participant receives the more effective treatment

Explanation

Random assignment distributes characteristics, including ones the researchers have not measured, roughly evenly between groups. This reduces the chance that an observed difference reflects pre-existing differences rather than the treatment.

Question 31The Foundations of Scientific Thinking

A class debates whether a claim about a herbal remedy should be accepted. Which action best reflects the principle of scepticism in science?

  1. Accepting the claim because it has been repeated by many people
  2. Requesting evidence and considering whether it can be independently checked Correct answer.
  3. Adopting the claim provisionally because it seems harmless
  4. Rejecting the claim immediately because it is unfamiliar

Explanation

Scientific scepticism means withholding acceptance until claims are supported by evidence that others can examine and verify. It is neither automatic belief nor automatic rejection, but proportionate doubt tied to evidence.

Question 32The Foundations of Scientific Thinking

Which feature most clearly distinguishes science from other ways of understanding the world?

  1. Its use of specialised technical vocabulary
  2. Its interest in explaining natural events
  3. Its reliance on systematic evidence and methods open to scrutiny Correct answer.
  4. Its dependence on the authority of respected individuals

Explanation

Science is characterised by systematic observation and reasoning whose methods and evidence can be examined, criticised and repeated by others. Vocabulary, authority and interest in nature are shared with many other activities.

Question 33The Foundations of Scientific Thinking

A scientist reports a result and another team obtains a different value using the same method. What does this most directly illustrate?

  1. That at least one team has acted dishonestly
  2. That the method must be invalid
  3. That scientific knowledge is purely a matter of opinion
  4. That measurement in science can involve variability and requires replication Correct answer.

Explanation

Repeated measurement commonly yields slightly different values because of random and systematic sources of variation. Comparing independent results is how science estimates that variability and checks whether findings hold up.

Question 34The Foundations of Scientific Thinking

A student concludes that a plant grew taller because it was spoken to daily, without measuring light, water or temperature. Which improvement most strengthens the investigation?

  1. Photographing the plant each day for the school newsletter
  2. Speaking to the plant more frequently and for longer
  3. Choosing a plant species that grows faster
  4. Recording the growth of several plants kept under controlled, comparable conditions Correct answer.

Explanation

To support a causal claim, the investigation must control or account for other factors that could affect growth and compare conditions fairly. Using several plants under controlled, comparable conditions reduces the influence of chance and confounding variables.

Question 35The Foundations of Scientific Thinking

A researcher reports that a new study method produced results consistent with predictions made before data collection. Why does this consistency strengthen the claim?

  1. Because it shows the researcher is experienced
  2. Because the method was expensive to develop
  3. Because predictions made in advance cannot be influenced by the data Correct answer.
  4. Because consistent results prove the underlying theory is true

Explanation

Predictions specified before data collection cannot be shaped to fit the results, so confirming them provides stronger evidence than explanations devised afterwards. This protects against the bias of adjusting hypotheses to match whatever data appear.

Question 36The Foundations of Scientific Thinking

A researcher uses a thermometer calibrated to read 0.5 degrees Celsius too high at every temperature. What type of error does this introduce?

  1. No error, because the shift is constant
  2. Random error that averages out over repeated readings
  3. A systematic error that shifts all readings in one direction Correct answer.
  4. A sampling error caused by the choice of thermometer

Explanation

A consistent offset affects every measurement in the same direction, which is the defining feature of systematic error. Repeating readings will not remove it, although calibration against a known standard can correct it.

Question 37The Foundations of Scientific Thinking

Two explanations exist for a set of observations. Which principle should guide a scientist choosing between them?

  1. Prefer the explanation that requires fewer unverified additional assumptions Correct answer.
  2. Prefer the explanation that is more complicated because it covers more possibilities
  3. Prefer the explanation proposed by the more senior researcher
  4. Prefer the explanation that has been described in the most engaging way

Explanation

When competing explanations fit the same evidence, the one invoking fewer unsupported assumptions is generally preferred because it makes fewer claims that could turn out to be false. This is the practical value of parsimony in reasoning.

Question 38The Foundations of Scientific Thinking

A scientist describes a finding as preliminary. What does this most reasonably signal about the claim?

  1. The claim is known to be false
  2. The claim rests on limited evidence and may change with further work Correct answer.
  3. The claim cannot be investigated scientifically
  4. The claim has been fully verified by independent groups

Explanation

Calling a finding preliminary indicates that the evidence base is incomplete and that conclusions may be revised as more data accumulate. It communicates appropriate caution rather than final certainty or falsity.

Question 39The Foundations of Scientific Thinking

An investigator wants to know whether a tutoring program improves numeracy. Which design best supports a causal conclusion?

  1. Comparing numeracy scores of randomly allocated tutored and untutored groups Correct answer.
  2. Comparing numeracy scores of students who chose tutoring with those who declined
  3. Asking students whether they felt tutoring helped them
  4. Comparing the school's numeracy average before and after the program began

Explanation

Random allocation creates groups that should be comparable apart from the tutoring, so any difference in numeracy can be attributed more confidently to the program. Self-selection and simple before-after comparisons leave alternative explanations open.

Question 40The Foundations of Scientific Thinking

A model of ocean circulation simplifies many real processes. Why is such simplification acceptable in scientific practice?

  1. Because simplified models are always more accurate than reality
  2. Because the omitted processes are known to have no effect
  3. Because models are only used for teaching rather than research
  4. Because simplification can isolate the processes most relevant to the question being asked Correct answer.

Explanation

Models deliberately abstract from reality so that key mechanisms can be represented and investigated. A simplification is justified when the omitted details are unlikely to matter much for the specific question being addressed.

Question 41The Foundations of Scientific Thinking

A scientist finds that a result holds only when a particular data-processing choice is made. What is the most appropriate interpretation?

  1. The finding depends on an analytical choice and requires checking under alternatives Correct answer.
  2. The finding is robust because a choice was made deliberately
  3. The finding proves that all other choices are wrong
  4. The finding should be reported without mentioning the choice

Explanation

If a conclusion changes with reasonable variations in analysis, its robustness is in doubt and the dependence should be investigated and disclosed. Testing alternative choices shows whether the result reflects the data or the analyst's decisions.

Question 42The Foundations of Scientific Thinking

Why is an operational definition important when a study measures something like attention?

  1. It guarantees that the concept has been measured without error
  2. It removes the need for statistical analysis
  3. It specifies the concrete procedure or measure used to quantify the concept Correct answer.
  4. It shows that the concept is identical in every context

Explanation

Concepts such as attention are abstract, so researchers must state exactly how they are measured, for example by reaction time on a task. Operational definitions allow others to replicate the measurement and judge whether the results support the intended claim.

Question 43The Foundations of Scientific Thinking

A scientist reads a report claiming that a supplement improves memory and notices that the control group also took the supplement. What is the most significant problem with the study's design?

  1. The study should have used a different memory test
  2. There was no comparison group free of the supplement to isolate its effect Correct answer.
  3. The sample size was probably too small to matter
  4. The supplement was probably too expensive to be useful

Explanation

Without a group that does not receive the supplement, any change in memory cannot be attributed to the supplement rather than to other influences. A valid comparison requires groups differing in the treatment under test.

Question 44The Foundations of Scientific Thinking

A theory has survived many attempts to refute it. What is the most accurate description of its status?

  1. It is now a proven fact that can never be revised
  2. It is well supported by evidence but remains open to revision Correct answer.
  3. It should be replaced because it has been tested too often
  4. It is merely an opinion held by most scientists

Explanation

Surviving repeated testing gives a theory strong evidential support, yet scientific claims remain revisable if new evidence demands it. Support and certainty are therefore not the same thing.

Question 45The Foundations of Scientific Thinking

A researcher observes that two variables change together but suspects a third factor influences both. What does this suspicion concern?

  1. The wording of the research question
  2. The format used to display the data
  3. The possibility of a confounding variable Correct answer.
  4. The precision of the measuring instrument

Explanation

A confounding variable is associated with both the supposed cause and the outcome, creating an apparent relationship that may not be causal. Identifying plausible confounders is central to interpreting correlational evidence.

Question 46The Foundations of Scientific Thinking

A scientist uses a computer simulation to explore how a disease might spread. Which limitation is most fundamental to this approach?

  1. The simulation cannot be run more than once
  2. The simulation's conclusions depend on the assumptions built into it Correct answer.
  3. The simulation produces too much data to analyse
  4. The simulation is not a recognised scientific tool

Explanation

A simulation follows whatever rules and parameters its designers specify, so its outputs are only as trustworthy as those assumptions. Comparing simulations with observed data is one way to test whether the assumptions are adequate.

Question 47The Foundations of Scientific Thinking

A study reports an effect size with a confidence interval that includes zero. What is the most appropriate reading?

  1. The confidence interval should be ignored in favour of the point estimate
  2. The study has proven that no effect exists
  3. The effect is large and certain
  4. The data are compatible with no effect, so the finding is inconclusive Correct answer.

Explanation

A confidence interval spanning zero means that no effect remains among the plausible values consistent with the data. The estimate may still suggest a direction, but the evidence is not strong enough to rule out no effect.

Question 48The Foundations of Scientific Thinking

Two labs measure the same quantity. Lab A's mean is close to the accepted value but its readings vary widely; Lab B's readings cluster tightly but sit far from the accepted value. How should their results be described?

  1. Lab A is more precise; Lab B is more accurate
  2. Both labs are equally accurate and equally precise
  3. Lab A is neither accurate nor precise
  4. Lab A is more accurate; Lab B is more precise Correct answer.

Explanation

Accuracy concerns closeness to the true or accepted value, while precision concerns how closely repeated readings agree with one another. Lab A is nearer the accepted value but scattered, and Lab B is tightly clustered but offset.

Question 49The Foundations of Scientific Thinking

A research group reports only the analyses that produced statistically significant results, omitting the rest. Why does this practice threaten the validity of the published literature?

  1. It prevents the use of statistics in future research
  2. It distorts the evidence base by over-representing chance findings Correct answer.
  3. It reduces the number of authors who can be credited
  4. It makes the articles too short for readers to follow

Explanation

When only significant outcomes are reported, the literature overstates how often effects appear and can present chance results as reliable. The overall evidence base then misrepresents what the full set of analyses actually showed.

Question 50The Foundations of Scientific Thinking

A claim is framed so that any possible observation can be counted as supporting it. What is the most significant consequence for scientific evaluation?

  1. The claim requires no further communication to other scientists
  2. The claim cannot be tested, because no evidence could count against it Correct answer.
  3. The claim automatically becomes a scientific law
  4. The claim becomes more valuable because it explains everything

Explanation

If every conceivable observation is treated as confirmation, the claim makes no risky prediction and evidence cannot discriminate between it and its alternatives. Such a claim falls outside empirical testing, however appealing it may sound.