A crucial scientific skill is critically evaluating investigations — your own and others' — for assumptions, possible sources of error, conflicting evidence, and unanswered questions, rather than simply accepting a conclusion at face value. Sources of error might include a small sample size, an uncontrolled variable, imprecise equipment, or a biased sampling method. Building an evidence-based argument means clearly connecting your data to your conclusion, showing exactly how the evidence supports the claim, rather than just stating an opinion. When using someone else's data or claims, it's also important to consider any ethical issues or cultural protocols — like properly acknowledging sources and respecting any conditions around how that information can be used.
Example
A study concluding "this supplement improves memory" based on just 8 participants with no control group has an obvious source of error — the small sample size and lack of comparison group make it hard to trust the claim, even though the data technically showed improvement in those 8 people.
Key terms
Source of error:
A factor (like small sample size or uncontrolled variables) that could undermine a study's reliability.
Evidence-based argument:
A conclusion clearly and explicitly supported by the data collected.
Questions
1. Evaluating a scientific method critically means:
Checking for assumptions, errors and unanswered questions
Accepting every conclusion automatically
Ignoring how the data was collected
Assuming every study is perfect
2. A small sample size is an example of:
A possible source of error
A guarantee of accuracy
Something that never affects a study
A type of graph
3. An evidence-based argument:
Clearly connects data to the conclusion
States an opinion with no supporting data
Ignores the data collected entirely
Is based purely on feelings
4. A study with no control group and only 8 participants likely has:
A source of error worth questioning
No possible flaws whatsoever
The most reliable evidence possible
Perfect, unquestionable results
5. When using someone else's data, you should consider:
Ethical issues and proper acknowledgement of sources
Nothing about where the data came from
Only whether it supports your own opinion
Ignoring where the information originated
6. Uncontrolled variables in an experiment are:
A possible source of error
Never a problem for a study
Always irrelevant to the conclusion
A sign of a perfect experiment
7. Cultural protocols around data might involve:
Respecting conditions around how information can be used
Ignoring who the information belongs to
Never being relevant to science
Only applying to written texts, never data
8. Why might a study's conclusion be considered weak if it doesn't clearly explain how the data supports it?
A conclusion should be directly and explicitly justified by the evidence collected, not just stated as an opinion
A conclusion never needs to be connected to the data collected
Weak conclusions are always just as trustworthy as well-supported ones
The relationship between evidence and conclusion is irrelevant to evaluating a study
9. Why might imprecise equipment be considered a source of error in an investigation?
It could introduce inaccuracies into the measurements, affecting the reliability of the results
Imprecise equipment never affects the reliability of measurements
Equipment precision has no bearing on the trustworthiness of data
Imprecise equipment always improves the accuracy of an experiment
10. Why might a biased sampling method undermine confidence in a study's conclusion?
The sample might not fairly represent the wider population, skewing the results
Biased sampling always produces the most accurate possible results
Sampling method has no bearing on how trustworthy a conclusion is
A biased sample is always identical to a random one
11. Why is it useful to ask "what questions does this study leave unanswered?" when evaluating a scientific claim?
It highlights the limits of the current evidence and what further investigation might be needed
This question is irrelevant once a study reaches a conclusion
Every study fully answers every possible related question
Identifying unanswered questions weakens the credibility of good science
12. Why might conflicting evidence from two different studies on the same topic be worth investigating rather than simply picking whichever conclusion you prefer?
Understanding why studies conflict (different methods, samples, contexts) leads to a more accurate overall picture
Conflicting evidence should always be ignored entirely
You should always trust whichever study confirms your initial expectation
Conflicting results between studies never provide any useful scientific insight
13. Why is properly acknowledging the source of secondary data important, beyond just being polite?
It allows others to verify the data's origin and respects intellectual and, where relevant, cultural ownership
Acknowledging sources has no real importance in scientific work
Data sources never need to be identified or verified
This consideration only ever applies to written text, never to data
14. Why might a claim supported by multiple independent, well-controlled studies be considered stronger evidence than a single small study?
Multiple independent studies reduce the chance that one study's errors or biases explain the result
A single small study is always just as reliable as multiple independent large ones
The number of supporting studies never affects how strong a claim is
Independent replication has no bearing on scientific confidence
15. Why might respecting cultural protocols be especially important when using traditional knowledge or data from a specific community?
Some knowledge is subject to specific conditions about how, when or by whom it can be shared or used
Cultural protocols never apply to any type of data or knowledge
All information is always free to use however a researcher wants
Cultural context has no bearing on how data should be ethically used
16. Why might a well-conducted experiment still be undermined by an overreaching conclusion — one that claims more than the evidence actually supports?
Even accurate data can be misused if the conclusion generalises far beyond what the specific evidence justifies
A conclusion can never claim more than what the data directly shows
Overreaching conclusions are always fully justified by any underlying data
The scope of a conclusion has no bearing on whether it is scientifically sound
17. Why might critically evaluating your OWN investigation (not just others') be an important scientific habit?
Recognising the limitations and possible errors in your own work leads to more honest, accurate conclusions
Scientists should only ever critically evaluate other people's work, never their own
Self-evaluation has no role in producing trustworthy scientific work
Your own investigation is always free from errors or limitations by default
18. Why might a claim based on evidence with several unaddressed sources of error still sometimes be worth taking seriously as preliminary, rather than dismissed outright?
It may point toward something worth further, more rigorous investigation, even if not yet fully conclusive
Evidence with any flaws at all should always be completely dismissed with no further consideration
Preliminary evidence is always exactly as certain as extensively validated evidence
Sources of error make a claim entirely worthless with no further scientific value
19. Why might evaluating the credibility of a claim's source (e.g. a peer-reviewed journal versus an unverified social media post) be an important part of assessing evidence?
Different sources undergo different levels of scrutiny and verification, affecting how much confidence to place in them
All sources of scientific claims should always be treated with identical credibility
The source of a claim never affects how trustworthy it should be considered
Peer review and social media posts provide equally rigorous verification
20. A news article cites "a study" showing a food additive is dangerous, but doesn't say who conducted it, the sample size, or whether it was peer-reviewed. Why is it reasonable to withhold full judgement until more details are available?
Without knowing the method, sample size and review process, it's impossible to properly evaluate the claim's reliability
A claim should always be fully trusted regardless of how much detail is provided
Missing methodological details never affect how a claim should be evaluated
Citing "a study" with no further detail is always sufficient evidence on its own
21. Understanding how to evaluate methods, claims and evidence mainly helps you to:
Critically assess the reliability and limitations of scientific claims, rather than accepting them uncritically
Accept every scientific claim exactly as presented with no further thought
Ignore possible sources of error in an investigation
Assume all evidence is equally strong regardless of its source or method
Answer key (parent copy)
1. Checking for assumptions, errors and unanswered questions
2. A possible source of error
3. Clearly connects data to the conclusion
4. A source of error worth questioning
5. Ethical issues and proper acknowledgement of sources
6. A possible source of error
7. Respecting conditions around how information can be used
8. A conclusion should be directly and explicitly justified by the evidence collected, not just stated as an opinion
9. It could introduce inaccuracies into the measurements, affecting the reliability of the results
10. The sample might not fairly represent the wider population, skewing the results
11. It highlights the limits of the current evidence and what further investigation might be needed
12. Understanding why studies conflict (different methods, samples, contexts) leads to a more accurate overall picture
13. It allows others to verify the data's origin and respects intellectual and, where relevant, cultural ownership
14. Multiple independent studies reduce the chance that one study's errors or biases explain the result
15. Some knowledge is subject to specific conditions about how, when or by whom it can be shared or used
16. Even accurate data can be misused if the conclusion generalises far beyond what the specific evidence justifies
17. Recognising the limitations and possible errors in your own work leads to more honest, accurate conclusions
18. It may point toward something worth further, more rigorous investigation, even if not yet fully conclusive
19. Different sources undergo different levels of scrutiny and verification, affecting how much confidence to place in them
20. Without knowing the method, sample size and review process, it's impossible to properly evaluate the claim's reliability
21. Critically assess the reliability and limitations of scientific claims, rather than accepting them uncritically