Part 2 – Evaluation of Findings (distinction) Broken down into 5 areas: Evaluation of statistical data Evaluation of conclusions drawn Evaluating limitations of the experiment Assessment and relevance of information sources Evaluation of proof of hypothesis

Evaluation of Statistical Data Comment on graph and standard deviation Standard Deviation A statistical test which measures the spread of the data from the mean (the variance from the mean). The larger the standard deviation the larger the variance from the means and therefore the less reliable the measurements for that value are. It was used to (hopefully) show the reliability of the data and therefore support your hypothesis. It should show you which results were the most reliable (state the value and the standard deviation and which were the least), are these the ones you expected based on your pattern of results i.e. are these results that do not follow the pattern as well as the others.

Evaluation of Statistical Data Graph A graph was used to visually represent the data so that patterns and relationships between the variables could easily be spotted. As the data is continuous a line graph was chosen as the most suitable type of graph to use. Range bars were used to visually show the spread of results for each value allowing a quick visual guide as to which set of results were the most or least reliable.

Evaluation of Statistical Data Did your graph allow you to easily identify patterns between your variables? Did your scale allow this to be a clear pattern? Would a different sized graph have been better? Did your range bars allow you to clearly make judgements on the precision and reliability of results for each value?

Evaluation of Conclusions Drawn Is there a link or relationship between the variables? No correlation/weak correlation/strong correlation/positive correlation/negative correlation As the (independent variable) increased from (value) to (value) the (dependent variable) increased/decreased from (value) to (value). Do the results support the hypothesis? Restate your hypothesis. Do have results that support this hypothesis? Even if your method was closely followed and correct your results may still not support this hypothesis.

Evaluation of Conclusions Drawn Have you identified errors in your investigation? Identify anomalous readings and errors. Make a comment on how you dealt with them. You may have decided to omit them from your mean calculation completely, explain and justify that here. You may have included them in your mean calculation and have considered them later when looking at the range bars and the standard deviation, explain that and justify it here.

Evaluation of Conclusions Drawn Were there any experimental problems? Make comments on any measurements that were difficult (e.g. pH 4) and on the suitability of the equipment – were they the correct size, was there any possible contamination or errors of measurement?

pH 4 took significantly longer than the other measurements, I had to use a cut off point, it is difficult to conclude when pH would have risen. The syringes were chosen specifically for the volume which they were going to measure. E.g. 5ml of water was measured using the 5ml syringe etc However, there is still room for error and issues with measurements could have be made. There was difficulty getting into the conical flask between each measurement and even though it was rinsed it wasn’t completely washed and any residue could have caused contamination. The same syringe was used to measure the different pH’s/concentrations which could have resulted in contamination. The same pestle and mortar was used to crush the different lengths of potato, even though it was rinsed in-between, it wasn’t cleaned thoroughly so there could have been contamination cumulatively with each measurement.

Evaluation of Conclusions Drawn Suggest possible improvements to your method. Perfect investigations do not exist. There is always something that can be improved. Justify your choices. Address the experimental problems if they can be improved.

Use an accurate micro pipette which allows you to set the specific volume to measure and measures it precisely. Use a new conical flask/pestle and mortar/bottle/syringe etc for each measurement to reduce the risk of contamination OR thoroughly clean in between each measurement using soap and hot water and allow to dry. Change the hydrogen peroxide concentration for each repeat so that the concentration has not changed between each measurement and will be the same number of hydrogen peroxide molecules and therefore the chance for the same number of successful collisions. Use a gas syringe to measure the oxygen gas given off which is more accurate than the measuring cylinder e.t.c.

Evaluating the limitations of the experiment Identify the limitations Explain the nature of the limitations Suggest how to reduce limitations/improvement Plan in the table and then write up, it will ensure that you cover all three of the above areas. Limitations could be due to method or equipment. There can and will be overlap between this and the previous section.

Evaluating the limitations of the experiment Measuring cylinder had a percentage error of... Inaccuracies in measuring the volume of gas at the start and end of the experiment resulting less accurate results Use a gas syringe attached to the conical flask so that it measures the gas more accurately. Oxygen gas dissolves in the liquid Less oxygen collected in measuring cylinder as it would have dissolved in the water on the way/ less oxygen formed on the disc as it has dissolved in the hydrogen peroxide, effecting the results Use a gas syringe attached to the conical flask so that it measures the gas directly without having to pass through water/ Complete more repeats to increase the reliability and eliminate any anomalous results

Other possible limitations: Unknown catalase concentration in potato/beetroot/liver/yeast – different pieces/solutions may have more or less each time than thought or stated Hydrogen peroxide concentration was retained between each repeat, it would have been broken down in each repeat reducing the concentration and therefore possibly effecting the number of successful collisions

Assessment and relevance of information sources Where your sources reliable and do they reflect current knowledge? Was your information taken from a reputable publication such as a textbook or independent source? Is there a clear indication that your information was written by informed experts in the field? Were any of your other sources, such as non-technical websites, also useful? Look back at your literature review and comment on those sources used as well as any additional ones you may have used since.

Evaluation of proof of hypothesis In this section you should state whether the data and evidence supports your hypothesis. Restate your hypothesis (yes, again!) State the conclusion you can draw from your investigation. Look at the pattern of results. Is this pattern what you expected based on your scientific knowledge? Are the results accurate? Do they follow the expected pattern? Were there any large sources of inaccuracies that could have affected your results? Are your results reliable and therefore add extra support to your hypothesis? Overall do the results support your hypothesis?

Evaluation of proof of hypothesis Does it encompass exactly what you set out to test? Does it fit with the assignment brief? Can the hypothesis be interpreted in a different way by someone else? Does it match with your initial assumption of the experimental outcomes? Was your hypothesis suitable or does the evidence suggest that another hypothesis could have been used?