ST2: Investigation Design & Constraints
Understand the practical constraints on statistical investigations including time, cost, ethics, confidentiality and other limitations, and how they affect the design of an enquiry.
Investigation Design & Constraints
Understand the practical constraints on statistical investigations including time, cost, ethics, confidentiality and other limitations, and how they affect the design of an enquiry.
Key Fact: Every statistical investigation has constraints that limit what is possible.
Key Fact: Time constraints affect how long you can spend collecting and analysing data.
Key Fact: Cost constraints limit the resources available — equipment, travel, printing, software.
Key Fact: Ethical issues include obtaining consent, avoiding harm, and being honest about results.
Key Fact: Confidentiality means personal data must be kept private and not linked to identifiable individuals.
Key Fact: The Data Protection Act and GDPR require personal data to be handled lawfully and securely.
Key Fact: Anonymity can be preserved by using codes or numbers instead of names on data sheets.
Key Fact: Practical constraints include access to participants, equipment availability and school policies.
Key Fact: A pilot study helps identify constraints before the main investigation.
Key Fact: The design of an investigation must balance ideal methods against what is realistic given the constraints.
Key Fact: You should always acknowledge limitations and explain how they might affect your conclusions.
Key Fact: Some investigations require ethical approval — in a school setting this means teacher and possibly parental consent.
📋 Key Vocabulary and Concepts
For Investigation Design & Constraints, you must know:
- Constraint: A factor that limits what can be done in an investigation.
- Ethics: Moral principles that govern how participants are treated in an investigation.
- Confidentiality: The obligation to keep participants' personal data private and secure.
- Informed consent: Agreement from participants after they have been told what the investigation involves.
- Pilot study: A small-scale trial run of an investigation to check for problems before the full study.
- Anonymity: Ensuring participants cannot be identified from the data collected.
❓ Practice Questions
Q: Name three practical constraints that might affect a statistical investigation.
Q: Why is confidentiality important in a statistical investigation?
Q: How can a pilot study help with investigation design?
Q: What is informed consent?
Q: Why should you acknowledge limitations in your conclusions?
✅ Answers
- Time, cost, and access to participants or equipment.
- To protect participants' privacy and comply with data protection laws; it also encourages honest responses.
- It identifies practical problems, unclear questions and constraints before the main data collection begins.
- Permission given by participants after they have been fully told what the investigation involves and how data will be used.
- Because limitations may affect the reliability or validity of results, and readers need to know how much confidence to place in the findings.
🎯 Exam Tips
- When asked about constraints, be specific — give concrete examples relevant to the investigation.
- Ethics questions often ask about consent and confidentiality — mention both.
- Use the term 'pilot study' when discussing how to test an investigation design.
- If evaluating an investigation, always comment on constraints and how they affect conclusions.
- Remember that constraints are not just negatives — they shape good investigation design.
📝 Exam Technique
GCSE Statistics Exam Tips — Investigation Design & Constraints:
1. For Investigation Design & Constraints questions, show every step of your working clearly — method marks count even if the final answer is wrong
2. Check your answer makes sense in context (estimation, units, reasonableness)
3. Use correct mathematical notation and state formulae before substituting values
4. If a Investigation Design & Constraints question asks you to 'prove' or 'show', write a logical chain of reasoning with a conclusion line
5. For problem-solving, identify the topic first, then recall the relevant method
1. For Investigation Design & Constraints questions, show every step of your working clearly — method marks count even if the final answer is wrong
2. Check your answer makes sense in context (estimation, units, reasonableness)
3. Use correct mathematical notation and state formulae before substituting values
4. If a Investigation Design & Constraints question asks you to 'prove' or 'show', write a logical chain of reasoning with a conclusion line
5. For problem-solving, identify the topic first, then recall the relevant method
⚠️ Common Errors
✗ Saying 'cost' without giving a specific example ✓ Giving a specific example, e.g. 'the cost of printing 200 questionnaires may be too high for a school project.'
✗ Confusing anonymity and confidentiality ✓ Anonymity means participants cannot be identified at all; confidentiality means their data is kept private but the researcher may know who they are.
✗ Ignoring ethical issues in investigation design ✓ Always considering informed consent, right to withdraw, and data protection when planning.
✗ Thinking constraints are reasons to abandon an investigation ✓ Constraints are factors to work within — good design adapts to them, for example by reducing sample size or changing the method.
✍️ Model Answer
Full-Mark Response
A student plans to investigate how much time Year 10 students spend on social media. Identify three constraints and explain how each affects the investigation design.
1. Time constraint: The student has only two weeks to collect data. This limits the sample size, so they may need to survey fewer students or use an online questionnaire to reach more people quickly. 2. Confidentiality: Students may not want others to see their social media usage. The questionnaire should be anonymous (no names) and data should be stored securely so responses cannot be linked to individuals. 3. Ethical consent: Participants must agree to take part and be told how the data will be used. The student should include a clear statement at the start of the questionnaire explaining the purpose and guaranteeing anonymity. Under-16s may need parental consent.
📊 AO Deep Dive
Assessment Objective Analysis
AO1 (Knowledge & Understanding): Demonstrate knowledge and understanding of investigation design & constraints, including data collection, presentation and calculation techniques relevant to Edexcel 1ST0 & AQA 8382.
AO2 (Application): Apply knowledge and understanding of investigation design & constraints to interpret data, reason statistically and draw conclusions in context.
AO3 (Evaluation): Evaluate statistical methods and conclusions, assessing appropriateness, reliability, validity and bias through the statistical enquiry cycle.
📝 Exam Questions by Topic
- AQA Past Papers - Topic Questions -- AQA
- Edexcel Past Papers - Topic Questions -- Edexcel
- CCEA Past Papers - Topic Questions -- CCEA
🎬 Video Resources
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