The IV is changed; the DV is measured
The independent variable (IV) is the variable the researcher changes; it has two or more conditions, since one gives nothing to compare. The dependent variable (DV) is the outcome the researcher measures, and it depends on which condition of the IV a participant was in. Two questions sort most scenarios: what did the researcher deliberately make different (the IV), and what did they count, time or score for everyone (the DV)? Naming only the memory test is too vague.
State the IV in full, with both conditions
Naming the topic of the IV is only half an answer: name the variable and both of its conditions. Incomplete — the IV was telephone numbers. Complete — whether the numbers were shown as one long string or split into groups of digits. The DV needs the same care: name the unit or count recorded, not the general area — the number of digits recalled, not memory. Write the IV as whether … or … and the DV as the number of, the time taken to or the score on …
Extraneous: situational vs participant
An extraneous variable is anything other than the IV that could affect the DV; left free to differ, it hides which one changed the DV. The specification names two kinds. Situational variables belong to the environment — noise, lighting, how busy a place is. Participant variables belong to the person and travel with them — age, prior knowledge, mood, being in a rush. Sorting test: would it still be true if the same person were tested elsewhere? If yes, participant.
Drawn from real examiner reports.
The IV and DV are swapped
Candidates report the measured thing as the IV and the changed thing as the DV. The check is one-directional: the researcher sets the IV first and reads the DV afterwards. If a value could only be known once a participant had finished, it is the DV. Fix it by writing both as one sentence first — the researcher changed whether … or … and measured the number of …
The IV and DV are recorded as swapped in June 2019 Paper 2 Q2a.
Naming the IV without both conditions
Giving the general topic of the IV rather than its two levels is incomplete. Naming the material in a memory study was not enough, because it never said what differed about how it was presented. An IV is a comparison, so it needs both sides: not telephone numbers, but whether they were shown as one string or split into groups.
November 2021 Paper 2 Q05a states that an IV must be given in full with both conditions, and that naming "telephone numbers" alone was not enough.
Situational and participant are muddled
The definition trap runs both ways: asked for a situational variable, candidates give something about the person; asked for a participant one, a feature of the setting. Examiners ruled that being in a rush is not situational — it depends on the person, not the environment. How busy a shop is belongs to the setting; being late for work belongs to the person.
June 2023 Paper 2 Q2c rules that being in a rush is not a situational variable because it depends on the person, not the environment. The reverse error — a situational variable given when a participant one was asked for — is reported in November 2020 Paper 2 Q04d.
Copying the scenario, not using it
When a question supplies a scenario, the marks come from using it, not reproducing it. Examiners record candidates copying from the stimulus and warn material should not be lifted. Repeating the question stem counts the same way, and naming the character is not application. Application means using the study's own conditions, measurement and setting, not echoing them back.
Copying rather than using the scenario is flagged in June 2023 Paper 2 Q16 and the June 2024 Paper 2 Introduction, which says candidates should not just lift information. Repeating the question stem is recorded in the June 2024 Paper 2 Summary and Q10; the character name alone is not application in June 2022 Paper 1 Q4b and June 2023 Paper 2 Q25.
Identifying without justifying it
Where a question asks you to explain an extraneous variable, naming one earns at most the first mark; the rest comes from saying how it could have affected the DV in this study. A two-part sentence carries both: one extraneous variable was … (name it and its type), and this could have affected the results because … (link it to the outcome, using the study detail).
Identification without justification is recorded in June 2024 Paper 1 Q11b and Q15b.
A difference needs a connective
Asked to describe a difference — say between a situational and a participant variable — candidates write two separate definitions and stop. That scores one mark. The second comes from a connective such as whereas or however: situational belongs to the environment, whereas participant belongs to the person. Define each, then join them comparatively.
That a describe-the-difference answer needs a connective rather than two separate definitions is recorded in June 2019 Paper 1 Q6 and June 2022 Paper 1 Q7.
The IV itself is not an extraneous variable
Asked to name an extraneous variable, a common answer is the IV restated, or the DV. Neither works: it must be a variable other than the IV that could affect the DV. The IV is the one the researcher wants to differ; the DV is the outcome, never the cause. It need not be something that went wrong — just anything left free to differ that could affect the DV.
One extraneous variable need not doom a study
Naming an extraneous variable does not by itself make a study useless — say which variable, which way it pushed results, and the doubt it leaves. Nor must such variables be removed: age and mood travel with the participant, so a researcher holds them constant or spreads them evenly. Credited standardisation answers were concrete.
June 2022 Paper 2 Q1b records that standardisation answers drifted onto controls, participant variables, sampling and ethics, and that the credited responses were concrete ones such as the same materials and the same timing for every participant.
Do the AO2 before any AO3
AO3 cannot be awarded without AO2 present: a general account with nothing from the study scores zero for evaluation as well as application. So write the IV and DV in full (AO1), quote its conditions and measurement (AO2), then judge its effect on your confidence (AO3).
Write both variables out first
First, on a variables question, write one sentence naming both: the researcher changed whether … or … and measured the number of … That forces the IV into two conditions and the DV into a countable outcome, giving the rest of the question something to attach to.
Read the sub-command before choosing
Marks are lost not to bad psychology but to the wrong sub-command: if a situational variable is asked for, a good participant one scores nothing, and vice versa. Underline the exact word — situational, participant, independent — before choosing which variable to name.
Independent variable (IV) — the variable the researcher changes or manipulates. It always has at least two conditions.
Dependent variable (DV) — the variable the researcher measures as the outcome of the study.
Extraneous variable — any variable other than the IV that could affect the DV.
Situational variable — an extraneous variable belonging to the environment or situation, such as noise, lighting or time of day.
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