Conclusion
Summarise your findings:
Answer the question you posed in your introduction.
Justify your answer by referring to your findings in your data analysis
Comment on your hypothesis (in your introduction)
Discuss any other relevant findings that may have some impact on your results:
Groupings - were there any groups and how could this have affected the analysis (effect of groups)
Size of data set - was there enough data to analyse
Unusual values - Did you have to retain any unusual values that could have affected the results.
Other models - Were alternative models considered - discuss these.
Bias - Were there any potential sources of bias in the data (how was it collected?)
Assumptions - Were any assumptions about the data made that could affect the analysis?
Relevance and usefulness - Are your findings going to be useful?
Finally evaluate the the whole investigation by suggesting any improvements that could be made. i.e What would you do different if you could do this again and were given more time?