What this lesson teaches
I can analyse qualitative and quantitative data and explain results that do not fit.
Syllabus 9173, Fieldwork, 3. Post-fieldwork stage. Students should be able to: organise and represent data using appropriate methods (see Additional Notes on Data); analyse the data using appropriate qualitative and quantitative methods.
Make a guess
Six residents walk 4, 5, 5, 6, 7 and 33 minutes to a clinic. Which average best shows a typical walk?
- The median, 5.5 minutes.
- The longest walk, 33 minutes.
- The mean, 10 minutes.
- Delete the 33 and report the rest.
Show the answer
The median, 5.5 minutes.
The single 33-minute walk pulls the mean up to 10 minutes. The median sits between the two middle values and is not dragged by the unusual one.
Describe the pattern with numbers, then check the spread, the exceptions and other possible explanations.
Clean your data first. Check units, missing values, duplicates and obvious mistakes. An unusual value is not automatically wrong. Keep it unless you have evidence it is an error, and note any you remove.
The mean adds all values and divides by how many there are. The median is the middle value in order. The mode is the most common. For walking times of 5, 5, 10, 15 and 40 minutes, the mean is 15, the median 10 and the mode 5. The range is 35. The long journey pulls the mean above the median.
Use proportions when groups differ in size. If 12 of 20 people and 18 of 60 people report a barrier, the rates are 60% and 30%. The bigger count does not mean a higher rate.
A scatter graph pairs two measurements from the same case. Describe direction, strength and exceptions. A link between distance and difficulty fits a distance effect, but mobility, crossings or heat may also matter. Tables need the same care: read units and totals.
- Mean, median, mode
- Average, middle value, most common.
- Range
- Highest minus lowest.
- Proportion
- Count divided by group size; compare rates, not counts.
Step by step
Summarise fairly
Pick the right average and show the spread.
Compare like with like
Keep units, totals and matching pairs.
Explain cautiously
A pattern is evidence, not proof of cause.
Worked example: Describe, then qualify
"Difficulty generally rises from 1 at 100 m to 5 at 500 m. But the 400 m journey is rated 3, below the 300 m journey's 4. The overall link supports studying distance, while the exception suggests other factors."
Watch out for this
The highest average shows the worst experience for everyone.
An average summarises a group. Look at the spread and exceptions.
Check your understanding
Which group has the higher barrier rate: 12 of 20 people, or 18 of 60?
- 12 of 20: 60%, compared with 30%.
- They have equal rates of about 45%.
- 18 of 60, because 18 people is more.
Show the answer
12 of 20: 60%, compared with 30%.
Yes. Compare rates, not counts.