Understanding the difference between data types and analysis methods is essential for selecting the right tool for the enquiry.
| Feature | Primary Data | Secondary Data |
|---|---|---|
| Source | Collected by the student in the field | Existing records (maps, census, news) |
| Purpose | Specifically tailored to the hypothesis | Provides context and historical comparison |
| Examples | Traffic counts, EQS scores | GIS maps, old aerial photos |
| Feature | Quantitative | Qualitative |
| --- | --- | --- |
| Nature | Numerical and statistical | Descriptive and visual |
| Tools | Mean, Range, Bar graphs | Annotated photos, Field sketches |
The principle of Reliability refers to the consistency of the data; if the enquiry were repeated under the same conditions, would it yield the same results?
Validity refers to the accuracy of the data and whether the methods used actually measure what they were intended to measure (e.g., does a 5-minute traffic count truly represent daily congestion?).
Sampling Bias must be minimized by selecting sites objectively rather than choosing locations that simply support the hypothesis.
Graph Completion: When asked to complete a graph, always use a ruler and match the existing style (e.g., same bar width or line thickness). Accuracy in plotting points is a common source of easy marks.
Anomaly Identification: Look for data points that do not fit the general trend. In an exam, you may be asked to suggest why these occurred (e.g., a temporary road closure during a traffic count).
Evaluation Questions: For 8-mark questions, focus on the 'three pillars': What went well (validity), what were the limitations (reliability), and how would you improve it (e.g., larger sample size or group data collection to reduce subjectivity).
Subjectivity in EQS: Students often forget that Environmental Quality Surveys are based on personal opinion. To fix this, researchers should use a group of people and take an average (mean) or most frequent (mode) score.
Confusing Range and Mean: Ensure you know the difference. The range is a measure of spread (), while the mean is a measure of central tendency ().
Ignoring Secondary Data: A common mistake is relying solely on field data. Secondary data is crucial for proving that the chosen day or site was representative of the wider urban area.