4.1 Data handling cycle - collection methods
Form questions, collect and organise representative data, and evaluate how design and sample choices affect conclusions.
How to study WJEC GCSE Mathematics and Numeracy
Move from concept and notation to a justified method, show a complete mathematical chain, check scale and units, and interpret the answer in context.
Core concepts
Concept 1
Use the statistical problem-solving cycle and form testable hypotheses.
Exam cue: Confirm the unit, entered tier, calculator condition and available formula list before choosing a method.
Concept 2
Design and criticise questionnaires and sampling methods.
Exam cue: Connect the collection method and sample to the population and hypothesis before judging bias or representativeness.
Concept 3
Organise qualitative, discrete and continuous data in tallies, tables and class intervals.
Exam cue: Show a complete mathematical chain, use correct notation and units, and interpret or check the result in its original context.
Concept 4
Current matrix coverage: Unit 1, Unit 3. Read the exact subpoint scope in each applicable unit column.
Concept 5
Foundation content is shown in standard type in the specification; bold additions apply only to Higher Tier.
Risk pitfalls and guardrails
Calling a sample large enough without examining selection bias, non-response or whether the population is represented.
Guardrail: Do not import the outgoing separate qualifications, assume a universal tier across units or ignore calculator, formula-list, context and accuracy conditions.
Assuming that every subpoint in a cross-unit strand appears in all three papers, rather than reading the correct matrix column.
Guardrail: Read the precise subpoint in the applicable unit column; a cross-unit strand does not mean every subpoint appears in every paper.
Using a Higher-only method or expectation for a Foundation entry, or importing the outgoing Mathematics/Mathematics-Numeracy structure.
Guardrail: Standard type applies to Foundation and Higher; bold specification additions are Higher-only. There is no Intermediate Tier.
Memory anchors
Population
The population is the full group about which a study seeks conclusions.
Sample
A sample is the subset from which data are collected.
Bias
Bias systematically favours some outcomes or groups.
Hypothesis
A hypothesis is a testable statement about a pattern or relationship.
Continuous data
Continuous data can take any value within an interval.
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
A survey records each student's number of siblings. How should this data type be classified?
Patients' heights are measured to the nearest millimetre. What underlying data type is height?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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