What makes a great lab report Conclusion?

Let’s look at each part in turn, remembering that where ABEL includes IV or DV, you need to include the Independent Variable and Dependent Variable of your experiment or investigation. 

The sections below offer a structure that can be used to help you at each stage, and these are then put together at the end of this page to give you an example Conclusion.

As we described in our article about the Hypothesis in a science lab report, it doesn’t matter whether you “got it right” or not. It doesn’t matter if your prediction was incorrect, perfectly correct, or the results don’t deliver a clear answer; if you describe why the results don’t fit, or fit, your hypothesis—that can still be enough to get you the top marks.

You can address the hypothesis at any point in the Conclusion, by stating whether your prediction was correct or not, but as starting a new section is the hardest part, many students prefer to do this first. You may therefore use a standard opening sentence to the Conclusion, something like:

Our hypothesis was correct, as the IV increased/decreased, the DV increased/decreased. This is because…..

As you can see, this structure reflects that used in the Hypothesis section, and it also leads nicely into discussing the results in relation to the Research Question.

A great Conclusion discusses the results in relation to the Research Question

You may have generated some surprising data, or made some interesting qualitative observations, but you should mention them after you have discussed the results in relation to the Research Question. This makes sure your Conclusion is focused and only relevant information is discussed, the reader’s focus is maintained and you are ticking all the right boxes on the mark scheme to get the top marks. 

This part can be a bit tricky and a common mistake is that students fail to provide enough evidence in the Conclusion to support their claims as they have written the Results section; they know what is in it and assume the reader does as well. However, you will have spent much longer getting to know the results than the reader of your lab report (probably your teacher) so you will need to be very clear. 

If you have prepared the ground adequately with the above structure (the This is because….. bit), then you can state at the end of the first paragraph something along the lines of:

Therefore the IV is positively correlated/negatively correlated/shows no correlation with the DV.

The above statement can be used to ‘jump off’ into the next paragraph. You might start this with 

This positive/negative/lack of correlation/normal distribution can be seen in Graph 1, where…..

Then you just need to describe what you see. Imagine you have never seen the graph (or graphs) before and someone has just handed it to you. 

What are the most obvious things that jump off the page? 

Note these down in bullet points and then turn them into sentences.

A great Conclusion provides specific examples of the results

This is not always required by teachers or specified in mark schemes, but infrequent references to specific examples of data, or data ranges, helps to focus your Conclusion and gives your explanations a more solid foundation when the reader sees that you are basing your work on actual measurements and calculations you have made. You may use a structure like this:

Graph 2 shows that when the IV increases by XX, the DV also increases, from YY to ZZ.

As can be seen in Table 1, the DV measurements range from XX to YY. The median measurement was ZZ.

Where XX, YY, and ZZ are place holders for examples of your data. To avoid producing a conclusion that is too formulaic, don’t see this part as where all references to data must occur; you can space out the references to your results throughout the Conclusion and include them at appropriate points.

A great Conclusion explains the trends in the results using science that was presented in the Background Information

A common mistake that science teachers often see, is a lack of science in the Conclusion! This is a strange thing to happen, as lab reports are generally written in science classes, after the students have been performing a scientific experiment. As we said at the start of this article, by the time a student starts to write the Conclusion, they are tired and running out of momentum. 

But this is a scientific report, so the Conclusion needs to have some scientific explanations in it, and where does that science come from? You can’t just pick new information and stick it in here, even if you had to do some more research to explain your results, it shouldn’t be so different to anything in your Background Information. 

If for example you need to include an explanation that talks about the density of a liquid, you may wish to add a sentence or two in the Background Information about how density of a liquid is calculated. It wouldn’t be appropriate to include the equation in the Conclusion, but you might need to use the science held in that equation in your Conclusion. 

Adding too much information that is general and not specifically related to your experiment or results will disrupt the flow and focus of your writing, may confuse the reader, and ultimately lose you marks. You might use a sentence like this to start your explanation:

The changes in the IV affected the DV by ……. . As described in the Background Information, this is because ……. . 

A great Conclusion discusses the validity of the results

A good way to link this section from the previous one, is to say whether your results agree with other studies/results/experiments/information you may have talked about in your Background Information. Like the Hypothesis, it is not the end of the World if your results are the opposite of what other experiments found, as long as you explain why this might have happened. 

You may therefore use sentences like these to summarise whether you feel your results are valid or not:

This finding is in line with the results of the experiment by AA (ref) as described above.

Our results therefore agree with AA who also found that as IV increases, DV increased/decreased because of ….., (ref)

However, this does not agree with the theory of WW, as outlined in the Background Information. This may be because….

Where AA could be the name of a researcher or website, WW could be the name of a theory or researcher, and (ref) means you should include the same reference as you used in the Background Information.

A great Conclusion describes the impact of erroneous results/measurement errors on the results.

Properly commenting on any strange measurement values or inbuilt error of your equipment does not make you sound like a bad scientist, in fact, it allows the reader to decide on the validity of the results, and leads you nicely into the next part of the Conclusion. Don’t be tempted to say something like 

“Everything went perfect and our results were amazing” 

- as has been seen in some lab reports! Be honest and remember you are doing this in a school lab or even online, so some error is expected; you’re (probably) not working at CERN!

A simple statement acknowledging any erroneous results and the limits of your equipment is fine:

Two measurements were repeated due to the values being so different to the others taken during the experiment. This was done so as not to impact the average values. However, as noted in the materials section, the MM had an error of ± 1 unit, so although this was used to record every value, this should be taken into account. 

Where MM is a piece of equipment, and unit is whatever unit was used to measure the DV.

As you can see, this leads nicely into:

A great Conclusion discusses the reliability, repeatability, and suitability of the method in relation to the Research Question

After you have written a clear and robust explanation of your results, a good way to wrap-up the Conclusion section and show the reader it is coming to an end, and you can place what you have done in the lab in a wider setting, you can write about how good the method is in general. This can be confusing, because the next section of the lab report, the Evaluation, is also about ‘how good’ the Method was. So what’s the difference?

In the Conclusion, this part is a lot shorter than that in the Evaluation; and whereas the Evaluation talks about specific points in the Method, here you write about more general points: Can you completely trust your results? Could other researchers easily follow the method and get similar results? Did the Method produce results that could completely answer the Research Question?

You might briefly summarise these points by writing:

Because the DV measurements did not differ greatly from the averages, our findings can be seen as being reliable and the method robust enough for other people to follow and get similar results. However, the graph shows the optimum IV may be in the range of AA–BB, therefore in order to provide an exact optimum value, the method could be revised to focus on this range. 

Where AA and BB are values from your data/graph.

These points might not be relevant for every experiment you do, or your teacher might not be looking for all these points every time, but if you get in the habit of thinking about these issues, when you come to designing your own investigation you will be well placed to get the top marks. 

AND FINALLY:

A great Conclusion outlines possible work for the future

As with most things, always try to end on a positive! This is a standard end to a lab report or Conclusion section. Again, it lets the reader know you are finishing up this section, places your project into a wider context, and allows you to change negative things into a positive. Realistically, you probably won’t repeat the experiment but you might do other experiments related to it, but you can talk as though you will be repeating and revising the Method. For example, you might write:

This experiment shows that as XX is dependent on YY, this finding may be of use to ZZ. In the future, experiments could be designed to calculate the optimum amount of XX needed to produce the biggest increase in ZZ.

As our results are so different to those produced by other researchers, in the future we would investigate this by….

Unfortunately, as no conclusion could be made due to our results containing so many erroneous measurements, the method needs to be redesigned. The following evaluation section looks at specific problems with the method in more detail.

As you can see, there is again some overlap with the Evaluation, so you may put work for the future at the end of that section, or link to the Evaluation with a sentence similar to the one above.

Looking for more specific guidance on how to write a lab report specific to your age or syllabus? 

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