Measures of Central Tendency: These provide a single value that represents the 'center' of a data set. The Mean is the arithmetic average, the Median is the middle value in a ranked list, and the Mode is the most frequent value.
Measures of Dispersion: These describe how spread out the data is. The Range is the difference between the maximum and minimum values, while the Interquartile Range (IQR) focuses on the middle 50% of the data to reduce the impact of outliers.
Anomalies: These are data points that deviate significantly from the established pattern. In analysis, anomalies must not only be identified but also explained by considering external factors like human error or unique local conditions.
| Feature | Quantitative Analysis | Qualitative Analysis |
|---|---|---|
| Data Type | Numerical, measurable values | Descriptive, non-numeric info |
| Tools | Mean, Median, Mode, Range | Annotations, sketches, interviews |
| Objectivity | High; based on hard numbers | Lower; based on human perception |
| Goal | Identify statistical significance | Understand meaning and context |
Mean vs. Median: The mean is sensitive to extreme outliers, which can pull the average away from the typical value. The median is more 'robust' because it only considers the middle position, making it better for skewed data sets.
Description vs. Explanation: Description states what the data shows (e.g., 'The graph rises'). Explanation states why it shows that (e.g., 'The graph rises because increased velocity leads to higher erosion rates').
The 'Anomaly' Rule: Always look for the point that doesn't fit the line of best fit. Examiners often award marks for identifying an anomaly and suggesting a logical geographical reason for its existence.
Use Data Evidence: When describing a trend, never just say it 'increases.' Always quote specific figures from the axes (e.g., 'The value increased from 10 units at Site A to 50 units at Site E').
Check the Units: Ensure all statistical calculations include the correct units of measurement (e.g., , , or degrees).
Verify Calculations: A common mistake is miscalculating the mean by forgetting to divide by the total number of samples (). Always double-check the sum and the divisor.