Presenting Your Data

📊 Presenting Your Data

How you present data matters — different variables call for different graphs. Choosing the wrong graph type loses marks in the exam. Here is the standard approach for river fieldwork data:

Scatter Graphs

Use a scatter graph to show the relationship between two continuous variables — for example, distance downstream (x-axis, in km or metres) and velocity (y-axis, in m/s). Plot a line of best fit through the data. The slope and direction of the line shows you whether the relationship is positive (as x increases, y increases) or negative.

You can draw separate scatter graphs for: velocity vs distance, pebble size vs distance, pebble roundness vs distance, channel width vs distance, channel depth vs distance.

Channel Cross-Section Profiles

Draw a cross-section diagram for each site. Plot the channel width on the x-axis (in metres, starting at 0 for the left bank) and depth on the y-axis — but invert the y-axis so that deeper readings point downwards (like a river bed). Plot all your depth readings across the channel width at that site. Connect them with a smooth line to show the shape of the river bed. This allows you to visually compare how channel shape changes from one site to another.

Proportional Diagrams

A table of means for each variable at each site is essential — it summarises all your raw data into a form that can be graphed and compared directly. Always include a column for the distance of each site from the source.

Rose Diagrams / Pebble Roundness

Pebble roundness can be presented as a bar chart (x-axis = roundness category 1–6, y-axis = frequency or percentage of pebbles). Comparing bar charts between sites reveals whether roundness increases downstream as predicted.