Designing a Scientific Investigation

Scientific Method

  • Sequence: Observe & Question → Research → Formulate Hypothesis → Test → Analyse & Conclude → Report/Share
  • First step: Ask a question / Make an observation\text{Ask\ a\ question / Make\ an\ observation} (problem identification)

Research Question & Aim

  • Research Question: precise, answerable inquiry defining study focus
  • Aim: concise statement of investigation’s purpose (what you seek to discover)

Hypothesis

  • Testable prediction linking variables
    • Null: no relationship
    • Alternative: relationship exists
  • Write as: “If IV\text{IV} is changed, then DV\text{DV} will respond.”

Variables

  • Independent Variable (IV): factor deliberately changed; the “cause”
  • Dependent Variable (DV): factor measured; the “effect”
  • Controlled / Constant Variables: kept the same to isolate IV effect
  • Control Group: baseline group without IV manipulation; used for comparison

Data Handling

  • Observation & Measurement → record using drawings, tables, graphs
  • Analyse: look for patterns/trends; distinguish correlation vs causation
  • Conclusion: judgment based on data; relates back to hypothesis

Validity, Reliability, Accuracy

  • Validity: only IV influences DV (control constants & design)
  • Reliability: repeatability; increase by replication & larger sample size
  • Accuracy: closeness of measurements to true value; improve via calibrated instruments

% Change Formula (useful for Q6)

% change=new−originaloriginal×100\%\ \text{change} = \frac{\text{new} - \text{original}}{\text{original}} \times 100

Common Exam Triggers

  • Identify IV, DV, Control Group in scenarios
  • Match definitions: hypothesis, prediction, variable, control, conclusion
  • Ensure experimental improvements: add repeats, larger n, measure consistently, keep constants