Paper 5: Analysis and Evaluation Tips
A2 Practical Skills Paper
In this case, students must concentrate on planning, data analysis and interpretation and evaluation. They must know about descriptive statistics and also when and how to use two statistical tests: the χ2 test and the t-test. To prepare for this paper, students should do practical activities that generate data which they can analyse using statistical methods.
There are many topics in the AS and A2 courses which lend themselves to planning. Past papers are, of course, a good source of these. This is a list of skills that students need in order to make a good experimental plan:
1 Identifying key variables.
2 Describing, including diagrams, a workable practical procedure.
3 Selecting appropriate methods for varying and measuring the dependent variable.
4 Selecting appropriate methods for measuring the independent variable. 5 Selecting appropriate methods for standardising (or controlling) other variables (known as controlled variables or control variables).
6 Suggesting a suitable control experiment (if appropriate).
7 Suggesting a quantitative, testable, prediction.
8 Selecting equipment of a level of precision appropriate to ensure accuracy, e.g. choosing a balance that measures to the nearest 0.01 g rather than to the nearest 1.0 g.
9 Planning to collect sufficient results to ensure reliability.
10 Describing how results will be recorded.
11 Suggesting how results will be analysed.
12 Stating the risks involved in the practical procedure and giving precautions to take during the investigation.
Students can continue their planning by making notes under the following headings.
Suggest one or more suitable controls for this investigation. Again, this may not always be appropriate. You do not, for example, always have to use a boiled enzyme, or a tube containing water instead of enzyme, as a control in enzyme experiments.
Suggest a suitable prediction for this experiment. This is not always appropriate. For example there is no point in trying to predict an optimum pH. The prediction here could be that an optimum pH will be found.
• Outline a suitable procedure to carry out this investigation
This is best written as a set of numbered points; step 1, step 2, etc. This makes it easy to refer to steps that may need to be repeated in your plan.
Include a labelled diagram or a flow chart of your investigation if you think that will help show the steps in your plan.
• Results table
Prepare a table to record the results of your investigation.
Suggest what analysis you will perform on your results.
When students have finished making notes, they can write out their plans. If they are set a fairly simple plan, then they can carry it out and assess how well they have done.