Practical and Investigative Skills in Home Economics
This domain assesses how you plan, carry out and report a food or consumer investigation. Marks come from design rigour, consistent method, honest evaluation and correct hygiene and safety throughout.
Designing the investigation
- State an aim, then a testable hypothesis; identify the independent variable (what you change), the dependent variable (what you measure) and the controlled variables (what you hold constant).
- Plan sampling, ethical consent, allergen disclosure and a written risk assessment before practical work.
- Standardise recipes: weigh ingredients, record brands, oven temperature, portion size and timings, so the method is repeatable.
Methods of data collection
- Sensory evaluation: discriminative tests (triangle, duo-trio) detect differences; descriptive tests profile attributes; affective tests (nine-point hedonic scale) measure liking.
- Dietary assessment: 24-hour recall, estimated or weighed food diary, food frequency questionnaire - each with known limitations such as recall bias or under-reporting.
- Present results in tables and charts, then evaluate validity and reliability.
Hygiene throughout
Apply the four Cs - cleaning, cooking, chilling, cross-contamination - with separate boards for raw meat, core temperatures of 75 °C, and chilled storage at or below 5 °C.
Worked example
Testing whether a 30% reduced-sugar muffin is acceptable. Reasoning: bake control and trial batches to one standardised recipe; code samples randomly with three-digit numbers; serve 30 untrained panellists in identical portions at the same temperature under the same lighting; randomise sample order to prevent first-sample bias; score on a nine-point hedonic scale; compare mean scores. If the trial scores near the control, the modification is acceptable - but report the panel size and untrained status as limitations.
Traps
- Changing more than one variable at once.
- Too few panellists, or telling them which sample is 'healthy'.
- Presenting conclusions that the data cannot support.
- Omitting the risk assessment, costing or evaluation of the practical work.