Research methods (science inquiry): WACE Year 12 Psychology
“Science inquiry (formulating research and methodology): aims, research questions, variables (independent, dependent, control, extraneous and confounding), directional and non-directional hypotheses and qualitative inquiry questions; research designs (experimental and non-experimental, observational, case study, correlational, longitudinal, cross-sectional); sampling (convenience, snowballing, random, stratified) and random allocation; experimenter effect and demand characteristics; single-blind procedures and standardisation”
Science inquiry is examined in both Unit 3 and Unit 4. You must be able to identify the aim, write a research question, identify variables (independent, dependent, control, extraneous and confounding), write directional and non-directional hypotheses (or a qualitative inquiry question), choose a research design (experimental or non-experimental: observational, case study, correlational, longitudinal, cross-sectional), select participants (convenience, snowball, random or stratified sampling) and allocate them randomly, and minimise extraneous variables such as experimenter effects and demand characteristics using random allocation, single-blind procedures and standardisation.
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What this dot point is asking
The design brief requires at least 20 percent of the short answer section to come from the Science inquiry strand, and extended answers draw on it too. Most questions describe a study and ask you to apply these terms to it, so practise on unfamiliar scenarios. Data collection, analysis and evaluation are on the companion page, data collection and analysis; ethics is on psychological research and ethics.
Formulating research
- Aim: a statement of what the research sets out to investigate ("to investigate whether sleep restriction affects working memory in adolescents").
- Research question: the question the study answers, based on the aim ("Does restricting sleep to five hours reduce adolescents' scores on a working memory task?").
- Hypothesis (quantitative research): a testable prediction about the relationship between the IV and DV in a population.
- Directional: states the direction of the effect ("will score lower than").
- Non-directional: predicts a difference but not its direction ("will differ from").
- Inquiry question (qualitative research): an open question that guides the collection of descriptive data ("How do Year 12 students describe their experience of exam stress?").
Name the population, the operationalised IV (both conditions), the operationalised DV and, for a directional hypothesis, the direction. Example: "Year 12 students who sleep 9 hours will recall more words from a 20-word list than Year 12 students who sleep 5 hours."
Variables
- Independent variable (IV): the variable the researcher manipulates.
- Dependent variable (DV): the variable measured to see the effect of the IV.
- Control variable: a variable kept constant so it cannot affect the DV.
- Extraneous variable: any variable other than the IV that could affect the DV. SCSA groups them as:
- participant variables (age, prior knowledge, motivation);
- environment variables (noise, temperature, time of day);
- researcher variables (the researcher's tone, expectations or behaviour).
- Confounding variable: an extraneous variable that has affected the DV in a systematic way, so the researcher cannot tell whether the IV or the confound caused the change.
Research designs
| Design | What it involves | Strength | Limitation |
|---|---|---|---|
| Experimental | IV manipulated; experimental group receives the IV, control group does not; participants randomly allocated | Can show cause and effect | Often artificial; may lack ecological validity |
| Non-experimental | No manipulation of an IV; variables measured or observed as they occur | Can study things that cannot ethically be manipulated | Cannot establish cause and effect |
| Observational | Behaviour watched and recorded, often in a natural setting | Real behaviour in real settings | Observer bias; participants may change behaviour if aware |
| Case study | In-depth study of one person or a small group (such as Henry Molaison) | Rich detail on rare cases | Cannot be generalised; may rely on memory |
| Correlational | Measures two variables to see whether they are related | Shows strength and direction of a relationship | Correlation does not show causation |
| Longitudinal | Same participants studied repeatedly over a long time | Shows change within individuals | Costly; participants drop out |
| Cross-sectional | Different groups (such as age groups) compared at one time | Quick and cheaper | Group differences may be due to cohort, not age |
Selecting and allocating participants
The population is the whole group the researcher wants to draw conclusions about; the sample is the subset who take part.
| Sampling method | How it works | Strength | Limitation |
|---|---|---|---|
| Convenience | Uses people who are easy to reach (a psychology class) | Quick and cheap | Likely to be unrepresentative |
| Snowballing | Participants recruit other participants they know | Reaches hard-to-find groups | Participants tend to be similar; not representative |
| Random | Every member of the population has an equal chance of selection | Avoids selection bias | Needs a full population list; may still be unrepresentative by chance |
| Stratified | Population divided into subgroups; participants chosen from each in proportion | Sample mirrors the population on key characteristics | Time-consuming; needs population data |
Random allocation means every participant has an equal chance of being placed in the experimental or control group. It spreads participant variables evenly across groups and is different from random sampling, which is about who is selected in the first place.
Sources of extraneous variables and how to minimise them
- Experimenter effect: the researcher's expectations or behaviour influence the results, for example by unintentionally encouraging one group.
- Demand characteristics: cues that tell participants what the study is about, so they change their behaviour to fit (or defy) what they think is expected.
Ways to minimise extraneous and confounding variables named in the syllabus:
- Random allocation of participants to groups.
- Single-blind procedure: participants do not know which condition they are in, reducing demand characteristics.
- Standardisation of procedures and instructions: every participant gets the same instructions, materials, timing and conditions.
Does music affect concentration?
A teacher tests her own Year 12 class: students complete a maths task in silence on Monday and with music on Friday. Scores are higher on Friday.
- IV: music or silence. DV: maths task score.
- Sampling: convenience sample (her class), so results may not generalise to other students.
- Problems: the day of the week and practice at the task are environment and participant variables that vary with the IV, so they may be confounding. The teacher knows the hypothesis, so an experimenter effect is possible, and students may guess the aim (demand characteristics).
- Improvements: randomly allocate students to a music group and a silence group tested at the same time; standardise the task and instructions; use a single-blind procedure where students are not told the hypothesis; ideally use a larger, randomly selected sample.
Marker's note: tie each weakness to its type (participant, environment or researcher variable) and give a specific fix.
- Confusing random sampling with random allocation
- Sampling is about who is in the study; allocation is about which group they are in.
- Vague variables
- "Memory" is not a DV; "the number of words recalled from a 20-word list after 10 minutes" is.
- Calling every extraneous variable a confound
- It only becomes confounding if it varies systematically with the IV and affects the DV.
- Using terms outside the syllabus instead of the named ones
- Use single-blind, standardisation and random allocation, which are the control methods SCSA names.
Exam-style questions
Questions in the style of SCSA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
Original7 marksA researcher investigates whether elaborative rehearsal improves recall. Forty Year 12 volunteers are randomly allocated to two groups. Group A repeats a list of 20 words aloud; Group B links each word to its meaning. After 30 minutes, both groups write down as many words as they can. (a) Identify the independent and dependent variables. (b) Write a directional hypothesis. (c) Identify one extraneous variable and explain how it could be controlled.Show worked answer →
(a) 2 marks. IV: the type of rehearsal (maintenance rehearsal by repeating aloud, or elaborative rehearsal by linking to meaning). DV: the number of words correctly recalled after 30 minutes.
(b) 3 marks. Year 12 students who use elaborative rehearsal will recall more words from a 20-word list after 30 minutes than Year 12 students who use maintenance rehearsal. (Population, direction and both operationalised variables are needed.)
(c) 2 marks. Prior familiarity with the words (a participant variable) could affect recall. Control it by using unfamiliar or equally common words for both groups; random allocation also spreads such differences evenly across the groups.
Original6 marksCompare random sampling and stratified sampling, stating one strength and one limitation of each, for a study of stress in students at a school with 1200 students.Show worked answer →
A 6 mark response needs each method described (1 mark each), a strength of each (1 mark each) and a limitation of each (1 mark each).
Random sampling. Every student in the school has an equal chance of selection, for example by drawing 100 names from the full enrolment list. Strength: it avoids researcher bias in choosing participants. Limitation: by chance, some groups (such as Year 7s) may be over or under represented, especially in a small sample, and a complete list of the population is needed.
Stratified sampling. The school is divided into subgroups (strata) such as year levels, and participants are randomly selected from each stratum in proportion to its size. Strength: the sample reflects the make-up of the population on the chosen characteristic, improving generalisability. Limitation: it takes more time and requires detailed information about the population.
Practise this
Sources & how we know this
- Psychology ATAR course Year 12 syllabus (effective from 1 January 2024) — School Curriculum and Standards Authority (SCSA)
- Psychology ATAR course: syllabus and support materials — SCSA
- Past ATAR course examinations — SCSA