Interpreting
What you must understand
Interpreting means extracting meaning from data presented as tables, graphs, diagrams, keys, food webs or written descriptions. You need to identify the independent variable (on the horizontal axis) and the dependent variable (on the vertical axis), read the axis labels and units before looking at any data, and work out what each small grid square is worth. Look for trends (rising, falling, flat, cyclic), compare values across categories, spot anomalous points, and describe patterns in words using the data. Distinguish correlation from causation: two quantities rising together does not prove one causes the other. Use interpolation to read between plotted points and be cautious about reading beyond the plotted range. Diagrams and keys require careful matching of labels, arrows and symbols.
Traps to watch
- Misreading the scale because each square is worth 2, 5 or 10 rather than 1.
- Swapping the axes, or quoting a value without its unit.
- Treating a single unusual point as part of the trend instead of an anomaly.
- Claiming cause when the data show only a relationship.
- Reading a value from the drawn line when the question asks about an actual plotted point.
Worked example
On a graph where the vertical axis runs 0 to 50 with 10 small squares, each square is 50 ÷ 10 = 5 units. A point sitting two squares above the 20 line is therefore 20 + 2 × 5 = 30 units. General rule: value per square = labelled range ÷ number of squares, and always state the unit.