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VCE Extended Investigation study materials
VCE Extended Investigation study resources

VCE Extended Investigation practice questions

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Question 1Units 3 and 4 coursework: designing and conducting an extended investigation

In an Extended Investigation, what is the main purpose of a research question?

  1. To focus the inquiry and guide decisions about methods and evidence Correct answer.
  2. To summarise the final conclusions before data collection begins
  3. To list every source the student has already read
  4. To replace the need for a methodology section

Explanation

A research question defines the scope of the inquiry and directs choices about what evidence to gather, which methods suit the problem, and how findings will be judged. It is not a summary of results, since conclusions emerge from the investigation itself. A well-formed question keeps the study focused and makes the investigation manageable within the available time.

Question 2Units 3 and 4 coursework: designing and conducting an extended investigation

A student wants to investigate how sleep duration affects concentration in Year 12 students. Which formulation is the most appropriate research question?

  1. Does sleep matter for students?
  2. What is the average bedtime of Year 12 students at my school?
  3. How does reported sleep duration relate to performance on a sustained attention task among Year 12 students? Correct answer.
  4. Why is sleep important for teenagers in general?

Explanation

An effective research question specifies the population, the variables and the relationship being examined, making it testable and bounded. The option naming sleep duration, a sustained attention task and Year 12 students does all three. Broad or purely descriptive questions cannot be investigated rigorously within the constraints of an Extended Investigation.

Question 3Units 3 and 4 coursework: designing and conducting an extended investigation

What is the key difference between a hypothesis and a research question?

  1. A hypothesis is a testable prediction about the relationship between variables, while a research question frames what is being investigated Correct answer.
  2. A hypothesis is written after data collection, while a research question is written before
  3. A hypothesis must be phrased as a question, while a research question must be phrased as a statement
  4. A hypothesis applies only to qualitative studies, while a research question applies only to quantitative studies

Explanation

A research question identifies the focus of the inquiry, whereas a hypothesis goes further by stating an expected, testable relationship between variables. Hypotheses are typically derived from the question and from prior literature. Both are formulated before data collection and both can be used in either quantitative or qualitative traditions, though hypotheses are more common in quantitative work.

Question 4Units 3 and 4 coursework: designing and conducting an extended investigation

Which practice best demonstrates ethical conduct when recruiting participants for an investigation?

  1. Offering extra marks to students who agree to participate
  2. Selecting only participants likely to support the hypothesis
  3. Recording participants without telling them to reduce bias
  4. Obtaining informed consent and explaining the right to withdraw Correct answer.

Explanation

Informed consent requires that participants understand the purpose and procedures of the study and know they may withdraw at any time without penalty. This protects autonomy and is a core requirement of ethical research. Coercion, deception and selective recruitment all compromise participant welfare and the integrity of the findings.

Question 5Units 3 and 4 coursework: designing and conducting an extended investigation

A student plans to compare two teaching methods but cannot control which class receives which method. Which design is most suitable?

  1. A true experimental design with random assignment
  2. A purely theoretical review with no data
  3. A case study of a single student
  4. A quasi-experimental design using intact groups Correct answer.

Explanation

When participants are already organised into groups that cannot be randomly assigned, a quasi-experimental design is appropriate because it compares conditions while acknowledging limited control. True experiments require random assignment, which is not possible here. A single case study or a purely theoretical review would not allow the comparison the student intends.

Question 6Units 3 and 4 coursework: designing and conducting an extended investigation

What is the main function of a literature review in an Extended Investigation?

  1. To provide a substitute for the methodology section
  2. To list every book in the school library on the topic
  3. To establish what is already known and identify the gap the investigation addresses Correct answer.
  4. To prove the student's hypothesis is correct before data are collected

Explanation

A literature review surveys existing knowledge, shows how the investigation is situated within it, and identifies what remains unresolved. This justifies the research question and informs methodological choices. It does not prove a hypothesis in advance and cannot replace a methodology section.

Question 7Units 3 and 4 coursework: designing and conducting an extended investigation

Which source is most likely to provide credible, peer-reviewed evidence for a literature review?

  1. A personal blog recounting an anecdote
  2. A promotional brochure from a commercial company
  3. An anonymous post on a discussion forum
  4. A peer-reviewed journal article reporting original research Correct answer.

Explanation

Peer-reviewed journal articles have been scrutinised by independent experts, which increases confidence in their methods and claims. They report original research and cite their evidence. Anonymous posts, promotional material and personal blogs lack this scrutiny and may contain unverified or biased claims.

Question 8Units 3 and 4 coursework: designing and conducting an extended investigation

A student finds a statistic on a website with no author, no date and no cited source. What is the most appropriate response?

  1. Use the statistic only if it supports the hypothesis
  2. Cite the website as a peer-reviewed source
  3. Use the statistic because it appears on the internet
  4. Treat it as unreliable unless corroborated by a credible source Correct answer.

Explanation

Source credibility depends on identifiable authorship, currency, and evidence that can be checked. A statistic with no author, date or citation cannot be verified, so it should be treated cautiously and only used if confirmed elsewhere. Accepting it because it is convenient or available is a form of confirmation bias.

Question 9Units 3 and 4 coursework: designing and conducting an extended investigation

Which statement best describes the role of a methodology section?

  1. It states the personal opinions of the researcher
  2. It presents the results in tables and graphs
  3. It explains and justifies how the investigation was designed and conducted Correct answer.
  4. It reviews the existing literature on the topic

Explanation

The methodology section documents the design, participants, materials, procedures and analysis techniques, and justifies why these choices suit the research question. It enables readers to evaluate validity and to consider replication. Results, literature and personal opinion belong in other sections.

Question 10Units 3 and 4 coursework: designing and conducting an extended investigation

In a study measuring reaction time, a student uses the same stopwatch procedure and instructions for every participant. Which concept does this primarily support?

  1. External validity
  2. Triangulation
  3. Ethical consent
  4. Reliability Correct answer.

Explanation

Reliability refers to consistency and repeatability of measurement. Applying identical procedures and instructions to every participant reduces variation caused by the researcher, supporting consistent results. External validity concerns generalisability, triangulation concerns using multiple sources, and consent concerns ethics.

Question 11Units 3 and 4 coursework: designing and conducting an extended investigation

A questionnaire asks: 'How much do you enjoy the excellent new canteen menu?' What is the main problem with this item?

  1. It is too long for respondents to read
  2. It uses a double negative
  3. It requires a numerical response
  4. It is a leading question that presupposes a positive view Correct answer.

Explanation

The wording 'excellent new canteen menu' presents a favourable premise, which pressures respondents toward agreement and biases the data. A neutral item would ask about satisfaction without evaluative adjectives. Length, response format and double negatives are separate issues not present in this item.

Question 12Units 3 and 4 coursework: designing and conducting an extended investigation

What is the purpose of a pilot study in an Extended Investigation?

  1. To replace the need for a literature review
  2. To test procedures and instruments on a small scale before the main study Correct answer.
  3. To select only participants who will confirm the hypothesis
  4. To generate the final conclusions of the investigation

Explanation

A pilot study trials the instruments, instructions and procedures with a small group so problems can be identified and corrected before the main data collection. This improves the quality of the eventual data. It does not produce conclusions, replace literature, or serve to select favourable participants.

Question 13Units 3 and 4 coursework: designing and conducting an extended investigation

A student wants a representative sample of a large school population. Which sampling method is most appropriate?

  1. Convenience sampling of friends in one class
  2. Purposive sampling of the researcher's teachers
  3. Random sampling from the full student list Correct answer.
  4. Volunteer sampling through a social media post

Explanation

Random sampling from the complete list gives every member of the population an equal chance of selection, which supports representativeness. Convenience, volunteer and purposive sampling all introduce selection bias because inclusion depends on availability, self-selection or researcher choice. Representativeness matters when findings are to be generalised.

Question 14Units 3 and 4 coursework: designing and conducting an extended investigation

Which of the following is an example of primary data?

  1. A summary of findings from a published review article
  2. A table of statistics copied from a government report
  3. A newspaper article describing another study
  4. Measurements a student records during their own experiment Correct answer.

Explanation

Primary data are collected firsthand by the investigator for the specific purpose of the study. Measurements taken during the student's own experiment fit this definition. Statistics from reports, summaries of reviews and news accounts of other studies are secondary because they were gathered by someone else for another purpose.

Question 15Units 3 and 4 coursework: designing and conducting an extended investigation

A student records participants' responses as 'strongly agree, agree, neutral, disagree, strongly disagree'. What type of data is this?

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

Explanation

Likert-style response categories have a meaningful order but the distances between categories are not guaranteed to be equal, which characterises ordinal data. Nominal data have no order, interval data have equal intervals without a true zero, and ratio data have equal intervals and a true zero. Treating ordinal categories as interval can distort analysis.

Question 16Units 3 and 4 coursework: designing and conducting an extended investigation

Which measure of central tendency is most affected by a single extreme outlier?

  1. The median
  2. The range
  3. The mean Correct answer.
  4. The mode

Explanation

The mean uses every value in its calculation, so an extreme score can pull it substantially toward that value. The median depends on position rather than magnitude and is resistant to outliers, and the mode depends only on frequency. The range is a measure of spread rather than central tendency.

Question 17Units 3 and 4 coursework: designing and conducting an extended investigation

A student reports that a result is statistically significant at p < 0.05. What does this indicate?

  1. The observed result is unlikely under the null hypothesis Correct answer.
  2. The result is important in practical terms
  3. The sample size was too small
  4. The hypothesis has been proven true

Explanation

A p-value estimates the probability of obtaining results at least as extreme as those observed if the null hypothesis were true. A value below 0.05 indicates the result is unlikely under that assumption. Statistical significance does not establish practical importance, prove a hypothesis, or indicate sample size.

Question 18Units 3 and 4 coursework: designing and conducting an extended investigation

Which action best reduces the risk of bias when interpreting qualitative interview data?

  1. Selecting only quotes that support the researcher's view
  2. Discarding responses that seem unusual
  3. Having interpretations checked by a second researcher Correct answer.
  4. Reporting only the most dramatic statements

Explanation

Having a second researcher review the coding and interpretations, sometimes called inter-coder or peer checking, helps reveal subjective assumptions and improves trustworthiness. Selecting, discarding or dramatising responses introduces bias and misrepresents participants. Systematic, transparent treatment of all data is essential.

Question 19Units 3 and 4 coursework: designing and conducting an extended investigation

What is the main purpose of triangulation in an investigation?

  1. To increase confidence in findings by using multiple sources, methods or researchers Correct answer.
  2. To guarantee a statistically significant result
  3. To ensure the sample is randomly selected
  4. To eliminate the need for ethical approval

Explanation

Triangulation cross-checks findings against more than one source, method, dataset or investigator, so conclusions are less dependent on a single approach. Converging evidence strengthens confidence, while conflicting evidence prompts further inquiry. It does not ensure random sampling, remove ethics requirements or guarantee significance.

Question 20Units 3 and 4 coursework: designing and conducting an extended investigation

A student's investigation finds no significant difference between groups. What is the most appropriate way to report this?

  1. Report the null result honestly and discuss possible explanations Correct answer.
  2. Omit the result and report only the expected finding
  3. Claim the result proves the groups are identical
  4. Change the hypothesis to match the result without comment

Explanation

Honest reporting of non-significant findings is a core requirement of research integrity. The discussion can consider explanations such as limited sample size, measurement limitations or a genuine absence of effect. Omitting results, silently altering hypotheses or overclaiming proof misrepresents the evidence.

Question 21Units 3 and 4 coursework: designing and conducting an extended investigation

Which referencing practice best avoids plagiarism when paraphrasing another author's idea?

  1. Copying the sentence without quotation marks
  2. Rewording the idea and citing the original source Correct answer.
  3. Citing only sources that were published recently
  4. Rewording the idea and presenting it as original

Explanation

Paraphrasing changes the wording but not the origin of the idea, so the original author must still be acknowledged with a citation. Presenting reworded ideas as original, copying without quotation marks, or citing by date rather than relevance all fail to give proper credit. Accurate referencing protects academic integrity.

Question 22Units 3 and 4 coursework: designing and conducting an extended investigation

A student's data collection runs over several weeks and participants drop out. Which threat to validity does this most directly raise?

  1. History
  2. Attrition Correct answer.
  3. Instrument decay
  4. Testing effect

Explanation

Attrition occurs when participants leave a study before it finishes, which can bias results if those who leave differ systematically from those who remain. Instrument decay concerns changes in measurement tools over time, history concerns external events, and testing effects concern repeated exposure to measures. Dropout across time is the defining feature of attrition.

Question 23Units 3 and 4 coursework: designing and conducting an extended investigation

What is the main advantage of using a mixed-methods design in an Extended Investigation?

  1. It removes the need for a research question
  2. It guarantees that results will be generalisable
  3. It combines numerical and descriptive evidence to give a fuller picture Correct answer.
  4. It allows the researcher to avoid ethical approval

Explanation

Mixed-methods designs integrate quantitative data, such as scores, with qualitative data, such as interview accounts, so findings can be explained and corroborated more richly. They still require a clear research question, careful sampling for generalisability, and ethical approval. Combining methods adds depth rather than removing obligations.

Question 24Units 3 and 4 coursework: designing and conducting an extended investigation

A student claims that because two variables are strongly correlated, one causes the other. What is the main flaw in this reasoning?

  1. Correlation requires qualitative data
  2. Correlation always indicates a negative relationship
  3. Correlation does not establish causation and a third variable may explain the relationship Correct answer.
  4. Correlation cannot be calculated for two variables

Explanation

A correlation shows that two variables vary together, but it does not show that one produces the other. A confounding variable could influence both, or the causal direction could be reversed. Establishing causation requires stronger designs such as controlled experiments and consideration of alternative explanations.

Question 25Units 3 and 4 coursework: designing and conducting an extended investigation

When planning the timeline of an Extended Investigation, which approach best supports completion?

  1. Begin recruitment before defining the sample
  2. Set milestones with contingency time for ethics approval and data collection Correct answer.
  3. Collect all data first and decide the research question later
  4. Leave writing the report until the final week

Explanation

A realistic plan sequences tasks, sets milestones and builds in contingency for delays such as ethics review or participant recruitment. This reduces the risk of running out of time and allows revisions. Deciding the question late, delaying writing or recruiting without a defined sample all create avoidable problems.

Question 26Units 3 and 4 coursework: designing and conducting an extended investigation

A student writes a research question for an Extended Investigation. Which version is most suitable for systematic inquiry?

  1. What do teachers think about caffeine?
  2. Does caffeine affect people?
  3. How does caffeine consumption influence short-term memory recall in Year 12 students? Correct answer.
  4. Caffeine is interesting and worth studying.

Explanation

A workable research question names the variables, the population and the relationship under study, so it can be investigated with defined measures. It should be focused enough to answer within the available time and resources. Vague topics lack defined variables and cannot guide data collection.

Question 27Units 3 and 4 coursework: designing and conducting an extended investigation

A student forms the hypothesis 'Students who sleep more than eight hours will score higher on a memory test than students who sleep less than six hours.' Which feature makes this a testable hypothesis?

  1. It uses technical vocabulary about memory.
  2. It includes a personal opinion about sleep.
  3. It predicts a specific relationship between measurable variables. Correct answer.
  4. It states a conclusion that has already been proven.

Explanation

A testable hypothesis predicts a relationship between variables that can be operationalised and measured. Here sleep duration and memory test scores are both defined and comparable across groups. Opinions, jargon or pre-proven claims do not create testability.

Question 28Units 3 and 4 coursework: designing and conducting an extended investigation

In an investigation, what does the term 'operationalisation' of a variable mean?

  1. Choosing a statistical test for the variable
  2. Removing the variable from the analysis
  3. Defining exactly how the variable will be measured or manipulated Correct answer.
  4. Reviewing the literature about the variable

Explanation

Operationalisation converts an abstract concept into a concrete, measurable procedure, such as defining 'stress' as a score on a validated scale. This allows other researchers to understand and replicate the measurement. It is separate from literature review or statistical choice.

Question 29Units 3 and 4 coursework: designing and conducting an extended investigation

A student wants to investigate how a school community responds to a new recycling policy. Which research design would best capture both the extent of behaviour change and the reasons behind it?

  1. A mixed-methods design combining bin-weight data with interviews Correct answer.
  2. A purely qualitative set of unstructured observations
  3. A single case study of one student's recycling habits
  4. A purely quantitative survey of bin weights

Explanation

Combining quantitative measures of behaviour with qualitative accounts of reasons allows the investigation to address both 'how much' and 'why'. Neither data type alone fully answers a question about extent and motivation. A single case would not represent the community.

Question 30Units 3 and 4 coursework: designing and conducting an extended investigation

A student plans to interview classmates about their study habits. Which action best protects participants' rights?

  1. Obtaining informed consent and explaining how data will be stored Correct answer.
  2. Recording participants secretly to ensure honesty
  3. Sharing identifiable responses with teachers without asking
  4. Publishing full names alongside quotations

Explanation

Informed consent ensures participants understand the purpose, procedures and any risks before agreeing to take part. Clear data-storage and confidentiality arrangements protect privacy. Secret recording or publishing names without permission breaches ethical expectations.

Question 31Units 3 and 4 coursework: designing and conducting an extended investigation

A student is deciding how many participants to recruit for a quantitative survey. Which consideration is most relevant to this decision?

  1. The number of questions the student finds interesting
  2. The statistical power needed to detect the expected effect Correct answer.
  3. The colour scheme used in the questionnaire
  4. The length of the student's literature review

Explanation

Sample size in quantitative research should be planned around the effect size expected and the statistical power required to detect it reliably. Too small a sample increases the risk of inconclusive results. Personal interest or presentation choices do not determine sample adequacy.

Question 32Units 3 and 4 coursework: designing and conducting an extended investigation

A student uses a random number generator to assign participants to either a control or a treatment condition. What is the main purpose of this procedure?

  1. To ensure participants enjoy the task
  2. To make the study easier to describe in a report
  3. To reduce systematic differences between groups Correct answer.
  4. To increase the sample size

Explanation

Random allocation distributes known and unknown confounding characteristics across groups, reducing systematic bias. This strengthens the claim that any difference in outcomes is due to the treatment. It does not change sample size or participant enjoyment.

Question 33Units 3 and 4 coursework: designing and conducting an extended investigation

Which statement correctly distinguishes an independent variable from a dependent variable?

  1. The independent variable is manipulated; the dependent variable is measured. Correct answer.
  2. Both variables are manipulated by the researcher.
  3. Both variables are held constant throughout the study.
  4. The independent variable is measured; the dependent variable is manipulated.

Explanation

The independent variable is the factor the researcher changes or selects, while the dependent variable is the outcome measured in response. This directional relationship defines the logic of an experiment. Holding both constant would make an investigation impossible.

Question 34Units 3 and 4 coursework: designing and conducting an extended investigation

A student's survey asks participants to rate agreement on a seven-point scale from 'strongly disagree' to 'strongly agree'. What type of data does this produce?

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

Explanation

A Likert-type rating scale ranks responses in order but the distances between points are not guaranteed to be equal, so the data are ordinal. Nominal data have no order, and interval or ratio data require equal and meaningful intervals.

Question 35Units 3 and 4 coursework: designing and conducting an extended investigation

During data collection a student realises a question was misunderstood by many participants. What is the most appropriate action?

  1. Change the participants' answers to what they probably meant
  2. Ignore the issue and analyse all responses together
  3. Record the problem and consider excluding affected responses with justification Correct answer.
  4. Delete the whole dataset and abandon the investigation

Explanation

Transparently documenting problems and justifying any exclusion of affected data preserves the integrity of the analysis. Altering participants' responses would falsify data, and ignoring the problem would bias results. Abandoning a whole dataset is unnecessary when the issue can be managed.

Question 36Units 3 and 4 coursework: designing and conducting an extended investigation

A student calculates a mean score of 72 with a standard deviation of 15 for one group and a mean of 75 with a standard deviation of 2 for another. What does the comparison of standard deviations indicate?

  1. Both groups have identical variability
  2. The means of the two groups are equal
  3. The second group's scores are more spread out around its mean
  4. The first group's scores are more spread out around its mean Correct answer.

Explanation

Standard deviation measures the typical spread of scores around the mean, so a larger value indicates greater variability. The first group's standard deviation of 15 is much larger than 2, showing wider dispersion. Means and variability are separate features of a distribution.

Question 37Units 3 and 4 coursework: designing and conducting an extended investigation

A student wants to display the distribution of scores on a continuous test across many participants. Which graph is most appropriate?

  1. A map of the school
  2. A table of raw names
  3. A pie chart
  4. A histogram Correct answer.

Explanation

A histogram groups continuous scores into intervals and shows the shape of the distribution, including peaks and spread. Pie charts suit proportions of a whole, and the other options do not represent numerical distributions.

Question 38Units 3 and 4 coursework: designing and conducting an extended investigation

A student interviews six teachers and identifies recurring themes across their responses. Which analytic approach does this describe?

  1. Calculation of a correlation coefficient
  2. Random sampling
  3. Inferential statistical testing
  4. Thematic analysis of qualitative data Correct answer.

Explanation

Thematic analysis involves coding qualitative responses and grouping them into recurring patterns or themes. It is suited to exploring meanings and experiences rather than testing numerical hypotheses. Correlations and inferential tests apply to quantitative data.

Question 39Units 3 and 4 coursework: designing and conducting an extended investigation

A student reports a correlation coefficient of r = -0.82 between hours of revision and number of errors on a test. How should this be interpreted?

  1. More revision is strongly associated with more errors
  2. More revision is strongly associated with fewer errors Correct answer.
  3. Errors cause students to revise less
  4. There is no relationship between revision and errors

Explanation

A negative correlation of this magnitude indicates a strong inverse association: as revision hours increase, error counts tend to decrease. The value describes association, not causation. Interpreting the sign and strength together is essential.

Question 40Units 3 and 4 coursework: designing and conducting an extended investigation

A student writes: 'According to a 2019 study, teenagers need more sleep.' No author, title or journal is given. What is the main weakness of this citation?

  1. It states a finding rather than an opinion
  2. It refers to teenagers rather than adults
  3. It lacks sufficient detail for the reader to locate the source Correct answer.
  4. It uses too many words

Explanation

A citation must give enough detail, such as author, year, title and source, for a reader to locate and verify the evidence. Without these elements the claim cannot be checked. Word count and the population described are not the issue here.

Question 41Units 3 and 4 coursework: designing and conducting an extended investigation

A student finds that results from an earlier study contradict their own findings. What is the most appropriate response in the discussion section?

  1. Omit the earlier study to keep the report simple
  2. Change their own data to match the earlier study
  3. Claim the earlier study was definitely wrong
  4. Acknowledge the contradiction and discuss possible explanations Correct answer.

Explanation

Strong discussion sections engage honestly with conflicting evidence and consider methodological, contextual or sampling explanations. Omitting contrary findings misrepresents the field, and altering data is misconduct. Acknowledging disagreement strengthens the credibility of the analysis.

Question 42Units 3 and 4 coursework: designing and conducting an extended investigation

What is the main purpose of stating limitations in an investigation report?

  1. To increase the apparent length of the report
  2. To show how findings should be interpreted with appropriate caution Correct answer.
  3. To prove that the investigation has no weaknesses
  4. To excuse the researcher from following ethical guidelines

Explanation

Limitations identify constraints such as sample size or measurement issues that affect how far conclusions can be generalised. Discussing them demonstrates critical awareness and supports honest interpretation. They do not excuse ethical breaches or prove absence of weaknesses.

Question 43Units 3 and 4 coursework: designing and conducting an extended investigation

A student's conclusion states: 'The results prove that music improves concentration for all students.' Which criticism is most justified?

  1. The conclusion should not mention students at all
  2. The conclusion is too cautious and should be stronger
  3. The conclusion uses too many technical terms
  4. The conclusion overgeneralises beyond the sample studied Correct answer.

Explanation

Conclusions must be bounded by the sample, setting and measures used, so claiming an effect for 'all students' exceeds the evidence. Careful hedging and reference to the specific sample are expected. Overclaiming weakens the credibility of a report.

Question 44Units 3 and 4 coursework: designing and conducting an extended investigation

A student plans to analyse interview transcripts by first labelling meaningful segments with codes and then grouping similar codes. What is this process called?

  1. Randomising
  2. Trialling
  3. Calibrating
  4. Coding Correct answer.

Explanation

Coding is the process of assigning labels to meaningful units of qualitative data so that patterns can be identified and grouped into themes. It is a foundational step in qualitative analysis. Randomising, calibrating and trialling refer to other research procedures.

Question 45Units 3 and 4 coursework: designing and conducting an extended investigation

A student measures plant growth after applying different amounts of fertiliser while keeping light, water and temperature constant. What role do the constant conditions play?

  1. They act as the research question
  2. They act as controlled variables that reduce confounding Correct answer.
  3. They act as the independent variable
  4. They act as the dependent variable

Explanation

Controlled variables are held constant so they cannot explain differences between treatment groups. Keeping light, water and temperature fixed means growth differences can be attributed more confidently to fertiliser amount. The independent variable is the fertiliser quantity and the dependent variable is growth.

Question 46Units 3 and 4 coursework: designing and conducting an extended investigation

A student's investigation has a tight deadline and limited access to participants. Which planning strategy best supports completion?

  1. Recruiting participants only after writing the conclusion
  2. Adding extra research questions whenever a new idea arises
  3. Designing the study around available time and access from the outset Correct answer.
  4. Leaving data analysis until the final week

Explanation

Feasible planning matches the design, sample and methods to the real constraints of time and access. This prevents late-stage problems that threaten completion. Expanding scope or delaying analysis increases risk, and conclusions must follow data collection.

Question 47Units 3 and 4 coursework: designing and conducting an extended investigation

A student wants to compare the mean scores of two independent groups. Which type of analysis is most appropriate?

  1. A thematic coding of responses
  2. A frequency table of names
  3. A literature search
  4. An independent-samples t-test Correct answer.

Explanation

An independent-samples t-test compares the means of two separate groups on a continuous measure. It assesses whether any observed difference is likely to have arisen by chance. Thematic coding and literature searching do not test mean differences.

Question 48Units 3 and 4 coursework: designing and conducting an extended investigation

A student argues that because their interview study produced rich detail, the findings can be generalised to the whole country. Which assumption is flawed?

  1. Detailed data are always less valuable than numbers
  2. Qualitative studies cannot produce useful findings
  3. Interviews should never be used in investigations
  4. Rich qualitative detail always guarantees statistical representativeness Correct answer.

Explanation

Depth of detail does not make a small, purposively selected sample statistically representative of a whole population. Generalisation depends on sampling and design, not on richness alone. Qualitative findings can be valuable and transferable without being statistically generalisable.

Question 49Units 3 and 4 coursework: designing and conducting an extended investigation

A student uses a published questionnaire but does not check whether it measures the same construct in their own context. Which quality of measurement is most at risk?

  1. Validity Correct answer.
  2. Referencing style
  3. Word count
  4. Sampling frame

Explanation

Validity concerns whether an instrument measures what it is intended to measure in the given context. Using a tool developed for a different setting without checking it risks measuring something else. Word count, sampling frame and referencing style are separate concerns.

Question 50Units 3 and 4 coursework: designing and conducting an extended investigation

A student repeats the same measurement on the same stable sample three times and obtains very similar results each time. Which property does this demonstrate?

  1. High statistical significance
  2. High generalisability
  3. High ethical standard
  4. High reliability Correct answer.

Explanation

Reliability refers to the consistency and stability of measurements when repeated under the same conditions. Similar results across repeats indicate that the instrument is dependable. Generalisability, ethics and significance are distinct concepts.