Why data presentation matters
Once you've stood on a beach measuring pebbles and waves, you end up with a big messy table of numbers. On its own, that table is almost useless — nobody can look at 50 rows of digits and instantly "see" a pattern. Data presentation turns raw numbers into a visual story that makes patterns, trends, and anomalies jump out at a glance.
The trick the exam wants you to understand isn't just "how do I draw a graph" — it's which graph fits which type of data, because each graph type is built to answer a different kind of question.
Primary data — the graphs you'll actually be tested on
Primary data is data you collected yourself out in the field (pebble sizes, wave counts, beach gradients). Here are the three main graph types Edexcel expects you to know, and — more importantly — why each one is the right tool for its job:
Quick way to choose the right graph
Ask yourself: "Is this ONE thing changing over time/distance?" → line graph. "Am I comparing SEPARATE sites or categories?" → bar graph. "Am I checking if TWO variables are connected?" → scatter graph.
Worked Example — completing a bar graph and spotting the anomaly
From the exam
Students measured the mean shingle size (mm) at five sites along a beach:
| Site | Mean shingle size (mm) |
| 1 | 21.1 |
| 2 | 16.0 |
| 3 | 14.1 |
| 4 | 10.0 |
| 5 | 30.1 |
Sites 1–4 show a clear decreasing pattern as you move along the beach — the shingle is getting smaller and smaller. Then Site 5 suddenly jumps up to 30.1mm, completely breaking the pattern. That break in the pattern is your anomaly.
Possible explanations for the anomaly (you need TWO linked points for full marks):
- Human error measuring or calculating the mean, or an unrepresentative sample was chosen (1), which made the sediment appear bigger than it really was (1).
- The sample may have been taken from an area protected from wave action, e.g. near a groyne (1), meaning less erosion had taken place there (1).
- Site 5 may have experienced a recent rockfall (1), meaning the sample was larger and less eroded than the other sites (1).
Examiner tip
You'll never be asked to draw a whole graph from scratch — but you WILL be asked to complete an unfinished one using given data. Match the style already on the graph exactly: if bars are a certain width, keep that width; if dots are joined by a line, join yours too. Also practice drawing best-fit lines on scatter graphs and marking an "x" on anomalies — these are easy, guaranteed marks if you're careful.
Practice Question 1 2 marks
A student collected sediment size along a beach transect at five separate sites. Which type of graph should they use to present this data, and why?
Practice Question 2 2 marks
Suggest a reason why sediment size and beach gradient would be presented using a scatter graph rather than a bar graph.