Once you've completed your experiment and recorded your results, make sure they are put together in an organized manner. Keeping your records organized will not only impress the judges, but will also give you a clear picture on what you've done. Once you have put your data together, you will have to ascertain whether the results support your hypothesis or not. If the results do not support your hypothesis, you should also state the reasons for this. Think carefully why this is the case, using your data to support your reasons.
Ensure that you spend enough time analyzing the data and results of your experiment. Many scientists find it extremely useful to use tables, charts and graphs to visually represent the data collected from the experiment. One of the easiest ways to do this is to use Microsoft Excel or Google Docs (Spreadsheet). Ensure that the unit of measurement is clearly stated in your tables and graphs.
Where you have repeated your experiment several times (as mentioned, you should typically perform at least 3 trials of the same experiment), a table/chart can be very useful to help you summarize and present your data in a meaningful manner. Sometimes, it may be appropriate to provide a calculation of the average measurements.
For graphs, it's probably best that the X-axis represent your independent variable whilst the Y-axis represents the dependent variable. In our example, the independent variable is the sunscreen protection factor whilst (grouped by brands, as we performed this experiment with 5 brands of sunscreen lotion) the dependent variable is the UV index (UV reading). Take a look at the graph here.
As you can see, we used a different color for each SPF level (but re-used that color for that particular SPF level regardless of the brand). Different types of graphs are appropriate for different experiments.
There are many types of graphs that you can use, but the most common and effective types are the bar chart, as well as the line graph.
A scientist never gives up, even when the results of the experiment do not support his or her hypothesis! A scientist realizes that experiments with negative results are just as important as experiments with positive results - because they both provide objective, valid information about the topic that is being researched. You will notice that in some of the science projects contained on this website, some of them actually have a hypotheses that us rejected. Again, that's perfectly acceptable and the science fair judges will not penalize you for failing to prove your hypothesis.
Do not change your hypothesis, even if you are tempted to do so. Instead, you should provide possible explanations of why the results do not support your hypothesis. You should also suggest an alternative experiment to solve your "problem".
If the results do support your hypothesis, you should then summarize your findings in a short, clear narrative. Here, you should also re-state the problem, the hypothesis and some ways you can improve your experiment. In the example above, you could say:-