A2 1 Investigative Project as an internally assessed portfolio: developing a research question and hypothesis, planning and risk-assessing an extended investigation, collecting and statistically analysing data, drawing conclusions and evaluating, and referencing scientific sources.

What this unit is asking

A2 1 Investigative Project is an internally assessed unit, so there is no terminal written paper for it. You design and carry out an extended, largely independent scientific investigation and write it up as a portfolio that your centre marks against CCEA criteria and CCEA moderates. It is the A2 counterpart of AS 1, but more demanding: you take greater responsibility for the research question, the methodology, the statistical analysis and the critical evaluation, and you reference the scientific literature. It rewards the same data-handling skills that the externally assessed A2 units test in their data questions.

Developing the research question and plan

The project begins with background research into the topic, using textbooks and reliable scientific sources, which both justifies the question and informs the method. You then state a clear research question and a testable hypothesis (usually framed as a null hypothesis so it can be tested statistically). Planning identifies the independent, dependent and control variables, the range and number of values, the apparatus and its resolution, and a full risk assessment for any biological, chemical or physical hazards. A strong plan also anticipates the analysis: you decide in advance what data you need and which statistical test will suit it, so you collect enough repeats to make the test valid.

Collecting and analysing data

Choosing the right test matters: a test of difference (such as a t-test or a chi-squared test) suits comparisons between groups, while a correlation test suits relationships between two variables. The point of the statistics is to turn an impression ("the extract seemed to reduce growth") into a defensible judgement ("the difference was statistically significant at the 5 per cent level"). The analysis also describes the trend or pattern in the data and links it back to the underlying science from the rest of the qualification.

Conclusions, evaluation and referencing

The conclusion answers the research question using the evidence and the statistical result, and relates the finding to the relevant scientific theory. The evaluation is critical and detailed: it judges the reliability of the data (from the spread of repeats), the validity of the conclusion (from how well variables were controlled and how representative the sample was), identifies the main sources of random and systematic error, considers any anomalies, and proposes specific, realistic improvements and sensible extensions for further work. Finally, the project references the sources used, so claims are supported and the work shows academic honesty. Strong referencing and a balanced evaluation are what separate the highest-marked projects.

Examples in context

Example 1. Effect of an antimicrobial on bacterial growth. A common project measures the zone of inhibition around discs soaked in different concentrations of an antimicrobial, with a solvent-only control, several repeats and aseptic technique. A statistical test of difference judges whether the antimicrobial significantly reduces growth, linking the project to the microbiology and health content of the qualification.

Example 2. A correlation in human physiology. A student investigates whether resting heart rate correlates with a measure of fitness across a sample of volunteers, gathering paired quantitative data. A correlation test judges whether the relationship is significant, and the evaluation considers sample size, confounding variables and how representative the volunteers were, connecting the project to the cardiovascular content of Human Body Systems.

Try this

Q1. State what a null hypothesis is and why it is used. [2 marks]

• Cue. It states there is no significant difference or correlation; it allows a statistical test to accept or reject it objectively.

Q2. Explain why repeats are needed before a statistical test can be applied. [2 marks]

• Cue. Repeats give a mean and a measure of spread, so the test can judge whether a difference is larger than the random variation.

Q3. A test result has a probability of 0.10 of arising by chance, tested at the 0.05 level. State whether the null hypothesis is accepted or rejected. [1 mark]

• Cue. Accepted; 0.10 is greater than 0.05, so the result is not significant.