Writing Lab Reports

The Simple Report

The simple report is generally only two to five pages long, and usually consists of the following:

• Aims
• Method
• Results
• Conclusion
• Discussion
• References

Aims (or Objectives)

The purpose of the experiment.
There may be one aim or several. For instrumentation-based practicals it is customary to mention the apparatus to be used: for example, the aim for a biochemistry practical which uses a spectrophotometer to determine serum protein levels might be written as "to determine protein levels in normal serum samples by spectrophotometry".  

Method (or Materials & Methods)

How you carried out the experiment (and what reagents you used).
Normally, the method is given out as part of the practical notes and very rarely would you be required to rewrite it, although you may have to note any alterations. Some lecturers will be happy with a reference to the method, e.g. "see practical notes page xx - alterations noted" and others may require a photocopy of the method attached to the report (with any alterations noted).

Results

What you found.
This is the raw data and is best presented in the form of tables and graphs. Record your data in tables and use the tabulated data to do the graphs.

Record any data you have determined from the graph in a separate table. For example, if you are trying to determine protein levels by spectrophotometry, you would record all the spectrophotometry readings for your standards and samples in the first table, and use the standard readings to construct a graph of protein concentration versus absorbance readings (a standard curve). The concentration of the samples can then be worked out from the graph, and recorded in a separate table. If the amount of raw data is excessive, consider presenting it as an appendix.

Conclusion

An interpretation or summary (not a discussion) of your results.
This is normally a brief statement (e.g. "the concentration of protein in serum sample xyz was found to be xx g/L, which is within the normal reference range"), or it may even be a tabulated summary of results. It should always reflect the question(s) posed in the Aim(s).

Sometimes the conclusion is not separate from the discussion, i.e. you may be asked to give a combined "conclusion/discussion".

Sometimes the conclusion may be required to go after the discussion, in which case it will not be a summary of the results but will be what you conclude based on your discussion. This type of conclusion will probably be about a paragraph in length. 

Discussion

What the results mean, whether they were as expected (and if not, why not), any problems with the practical etc. For example, a result outside the normal reference range could indicate one or more disease states, which should be mentioned.

It is usual to run a positive and negative control with any analysis as a way of making sure that the method worked. This would be in the form of a normal and an abnormal control of known value for a practical like the serum protein analysis. If these controls give results within their expected ranges you can generally assume that your sample result is valid. If not, this is a good indication that something went wrong, somewhere!

Sometimes the controls are past their expiry date, which means you have no way of knowing if your results are valid. If your results are not what you expected (as frequently happens in biochemistry practicals), don't panic — you can often score excellent marks by being able to explain what went wrong.  

References

This is usually just a list of the sources you consulted for your discussion.