Collecting quantitative and qualitative evidence

Overview

Difference between quantitative and qualitative evidence, weaknesses of qualitative evidence and triangulation in fieldwork.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is the difference between quantitative and qualitative evidence?

   Model answer

   Quantitative evidence is numerical: measurements, counts, scores and percentages, such as channel depth in centimetres, pedestrian numbers, or the proportion of respondents travelling more than five kilometres. It can be graphed, averaged and tested statistically, and it is objective in the sense that repeating the measurement should give the same figure. Qualitative evidence describes qualities rather than amounts: field sketches, photographs, interview responses, written observations and opinions. It captures character, reason and perception, but it cannot be averaged and it depends on the judgement of whoever recorded it.

2. 2

   Why should an investigation use both quantitative and qualitative evidence?

   Model answer

   Because each answers a question the other cannot. Quantitative data establish that something is the case - that footfall halves beyond a certain distance, that environmental quality scores differ between two estates - and allow the pattern to be tested. Qualitative data explain why it matters and how it came about, through what residents say, what the buildings look like and what the fieldworker observed. Together they produce a conclusion that is both measurable and meaningful; alone, numbers lack explanation and description lacks evidence.

3. 3

   Where does qualitative evidence add something that measurement cannot?

   Model answer

   Wherever the geography turns on perception, meaning or condition. How safe residents feel in an area is not the same as the crime rate; why people oppose a development cannot be counted; the visible state of a sea wall or a housing estate tells you things no single measurement captures; and the appearance of a landform explains the process behind it. Qualitative evidence also picks up factors the investigator had not anticipated and so had not designed a measurement for.

4. 4

   What are the weaknesses of qualitative evidence?

   Model answer

   It is subjective, so two investigators can record the same site differently, and the recorder's expectations can shape what is noticed and written down. It is hard to summarise or compare systematically, cannot be tested statistically in its raw form, and can be selectively quoted to support a conclusion already reached. Small numbers of interviews or observations may not represent the wider population. It is strengthened by structuring the collection - using the same prompts, the same scoring criteria, the same photographic viewpoints - and by triangulating with quantitative data.

5. 5

   Give examples of qualitative primary evidence collected in the field.

   Model answer

   Annotated field sketches of a landform or a street; photographs taken from recorded viewpoints with the direction and time noted; written field notes describing conditions, sounds, smells and activity; responses to open questionnaire questions and transcripts of interviews with residents, shopkeepers or officials; and structured observation such as recording the condition of buildings or the type of activity taking place. Environmental quality and bipolar surveys sit between the two types, since they convert qualitative judgements into numerical scores.

6. 6

   Give examples of quantitative secondary sources a geographer would use.

   Model answer

   Census tables giving population, age structure, housing tenure, employment and travel to work; river gauging station records of discharge and level; long-run rainfall and temperature records from weather stations; traffic count and air quality monitoring data; house price and land registry figures; tourism and visitor number statistics; and health and deprivation indices. All of these give figures over periods far longer than a fieldwork day, which is precisely what primary collection cannot supply.

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