Lab report: discussion
time to complete: 30 minutes
We will now explore the discussion section of the report. This section includes your critical interpretation of the results you obtained. You may also include a critique of the approach you took or a brief note on the limitations of your methods. Remember that a critique is a detailed evaluation.
Analysis vs. Interpretation
The following table can help you develop a substantial discussion section as it combines analysis and interpretation of the data provided.
| Analysis | Interpretation | |
| Questions to ask yourself |
Explain what you know with certainty based on your results and draw conclusions. |
Find logical explanations for problems in the data. |
| Example | Since none of the samples reacted to the Silver foil test, therefore sulfide, if present at all, does not exceed a concentration of approximately 0.025 g/l. It is therefore unlikely that the water main pipe break was the result of sulfide-induced corrosion. | Although the water samples were received on 14 August 2000, testing could not be started until 10 September 2000. It is normally desirable to test as quickly as possible after sampling in order to avoid potential sample contamination. The effect of the delay is unknown. |
Adapted from University of Toronto (2005)
What to include?
In this section, you should address the following elements:
- whether your hypothesis is supported by the data
- if there were any anomalous results or data deviation
- derived logical conclusions about your research area based on your findings.
If your report does not include a conclusion, then in the discussion you should also:
- if possible, link your results to the existing literature
- explore the theoretical and/or practical implications of your findings
Task 8:
Read an extract from the discussion section of the lab report we looked at earlier. Find examples of the following elements:
- whether the hypothesis is supported by the data
- if there were any strange or unexpected results
- derived logical conclusions about the research area, based on the findings.
Discussion
The natural frequency of the bungee cord for each applied load was calculated from the spring constant values using Equation 4 (see sample calculation in the Results section). This data can be seen in Table 1. The predicted value of natural frequency for an applied mass of 250g (applied load of 2.45N) was 0.96 Hz. The natural frequency measured by experiment was 0.97 Hz, showing excellent agreement (approximately 1% different).
There were a number of sources of error in this experiment. The deflection of the cord could only be measured to ± 1mm and the scale could only be originally placed to the same degree of accuracy. This led to an inaccuracy of up to 20% for the smaller deflection measurements (around 10mm). For larger deflections (up to 740 mm), this inaccuracy reduced to 0.3%. Further error could have been introduced by deflection of the loading frame and slippage of the attachments at each end of the cord.
Another error arose from the assumption shown in Equation 3, that the gradient of the force-deflection graph can be approximated using the finite difference between consecutive data points. This error may be reduced by using more data points and a more accurate method of gradient approximation.
The main error in the measurement of the natural frequency was caused by the human reaction time of operating the stop watch and assessing the point at which four oscillations had occurred. These sources of error may be reduced by using a longer piece of cord, which would oscillate more slowly and by averaging over a large number of measurements.
Adapted from Beagles et al. (no date)
- whether the hypothesis is supported by the data
- if there were any strange or unexpected results
- based on the findings, derived logical conclusions about the research area
Discussion
The natural frequency of the bungee cord for each applied load was calculated from the spring constant values using Equation 4 (see sample calculation in the Results section). This data can be seen in Table 1. The predicted value of natural frequency for an applied mass of 250g (applied load of 2.45N) was 0.96 Hz. The natural frequency measured by experiment was 0.97 Hz, showing excellent agreement (approximately 1% different).
There were a number of sources of error in this experiment. The deflection of the cord could only be measured to ± 1mm and the scale could only be originally placed to the same degree of accuracy. This led to an inaccuracy of up to 20% for the smaller deflection measurements (around 10mm). For larger deflections (up to 740 mm), this inaccuracy reduced to 0.3%. Further error could have been introduced by deflection of the loading frame and slippage of the attachments at each end of the cord.
Another error arose from the assumption shown in Equation 3, that the gradient of the force-deflection graph can be approximated using the finite difference between consecutive data points. This error may be reduced by using more data points and a more accurate method of gradient approximation.
The main error in the measurement of the natural frequency was caused by the human reaction time of operating the stop watch and assessing the point at which four oscillations had occurred. These sources of error may be reduced by using a longer piece of cord, which would oscillate more slowly and by averaging over a large number of measurements.
Language
Like in the results section, the discussion section uses verb forms in a similar way.
The predicted value of natural frequency for an applied mass of 250g (applied load of 2.45N) was 0.96 Hz.
This led to an inaccuracy of up to 20% for the smaller deflection measurements (around 10mm).
Further error could have been introduced by deflection of the loading frame and slippage of the attachments at each end of the cord.
These sources of error may be reduced by using a longer piece of cord, …
… the gradient of the force-deflection graph can be approximated using the finite difference between consecutive data points.
This error may be reduced by using more data points and a more accurate method of gradient approximation.
The natural frequency of the bungee cord for each applied load was calculated from the spring constant values using Equation 4 (see sample calculation in the Results section).
This error may be reduced by using more data points and a more accurate method of gradient approximation.
The main error in the measurement of the natural frequency was caused by the human reaction time of…