Evaluating

Whilst carrying out your investigation, you may find that some of the ideas you had are not working well. You may wish to make changes in order to improve your method. If you do, then you should mention it in your evaluation. It is a sign of a good scientist and you will receive credit for explaining why you changed your plan. Even if you didn't change plan, saying in the evaluation any changes that you could have made to improve the method you used will gain you some credit.

Part of evaluation is spotting any results that are anomalous. These are results that don't fit the pattern. If you have the opportunity, you can repeat these parts of your experiment, otherwise you can discard them. Even if you do neither of those things, at least mention them and say why you think they are anomalous (e.g. they are too high or low to fit the pattern). Candidates taking the higher tier should then be able to decide how reliable the results are and if they are sufficiently good quality to support the conclusion.

Finally, to gain credit at the very highest level, you should decide on what you could do to extend your experiment to get additional evidence relevant to the investigation and write in your conclusion a plan of action for an experiment to carry out the extra research.