Inferential Statistics and Significance
Select and interpret inferential procedures from the research design, measurement level, hypothesis and critical-value rule.
How to study A-level Psychology
For every claim, identify the mechanism, supporting evidence, method, alternative explanation, practical implication and justified conclusion.
Core concepts
Concept 1
A test is selected from whether the hypothesis concerns difference or association, the participant design and the level of measurement.
Exam cue: State the difference-or-correlation purpose, design and measurement level when justifying a test.
Concept 2
A significance level sets the tolerated probability of a result under the null hypothesis; one- and two-tailed tests reflect directional logic.
Exam cue: Read the correct row and tail from any supplied critical-value table.
Concept 3
Observed and critical values, degrees of freedom and test-specific decision rules determine whether the null hypothesis is rejected.
Exam cue: Report statistical significance without claiming practical importance or certainty.
Targeted study blocks
Multi-board knowledge
Secure the shared psychological core
Secure the common logic of probability, test selection, statistical tables, significance and error rather than assuming every board supplies or emphasises the same named tests.
Scientific reasoning
Use evidence before reaching a judgement
Reach the correct statistical decision, then separate chance evidence from effect size, practical value, validity and replicability.
Risk pitfalls and guardrails
Selecting a test only because its name is familiar.
Guardrail: Do not memorise a study as an isolated story or assume that one board's named research and option choices apply nationally.
Treating p less than 0.05 as a 95% probability that the alternative hypothesis is true.
Guardrail: Do not memorise a study as an isolated story or assume that one board's named research and option choices apply nationally.
Using the same observed-critical comparison rule for every statistical test.
Guardrail: Do not memorise a study as an isolated story or assume that one board's named research and option choices apply nationally.
Memory anchors
Significance level
The significance level is the preset chance threshold for rejecting the null hypothesis.
One-tailed test
A one-tailed test evaluates an effect in a predicted direction.
Two-tailed test
A two-tailed test evaluates an effect in either direction.
Type I error
A Type I error rejects a true null hypothesis.
Type II error
A Type II error fails to reject a false null hypothesis.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which three features are central to choosing an inferential test?
Which test is appropriate for a correlation using ranked ordinal pairs?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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