Graph & Table Labelling Conventions
- There are specific conventions for labelling physical quantities in columns of data in tables and on graph axes
Table Conventions
- When labelling table headings, the symbol is presented first, then a forward slash and the unit
- e.g. Current with unit Amps – I / A
- The general convention for tables:
- The independent variable goes in the column on the left
- The dependent variable goes in the column on the right
- Sometimes, powers of tens are also included with the unit, such as t / × 102 s
- This means the column of data has been divided by 100 to save repeating lots of zeros in the table
- If the values of t in the table or axes on the graph are 1, 2 and 3, the actual values obtained for t are 100 s, 200 s and 300 s
- Any processed data (eg. averages) should be in columns to the far right
- All units should be in the table headings, not in the body
- Any raw data should be recorded to the resolution of the measuring instrument
- All data of the same type must be recorded to the same number of decimal places
- An example table and graph is shown below for a Velocity v Time graph:
The convention for labelling tables and graphs
Graph Conventions
- When labelling graphs:
- The independent variable should be plotted on the x-axis
- The dependent variable should be plotted on the y-axis
- Each axis should be labelled with the quantity and unit, separated by a forward slash just like the table headings
- The graph must cover over 75 % of the space provided
- This means either axis does not always have to start at 0
- The only exception to this is that a y-intercept must always be read from an axis that starts at x = 0
- A suitable scale must be used for each axis to provide this (in steps of 1, 2, 5 or a multiple of 10)
- When calculating a gradient, draw a triangle that covers at least 75 % of the data points
- Similar to table headings, powers of tens may also be included with the unit on the axes labels, such as t / × 102 s
- The data points should be made with a small sharp pencil
- The general convention is to put an 'x' instead of a dot, as this is clearer to see on graph paper
- A line of best fit should have roughly equal points on either side and should not be forced through the origin
- It must also be a thin line that is clear, drawn using a straight edge or ruler
An example of a correctly labelled and plotted graph
Examiner Tip
One way to remember which axis is labelled with the independent and dependent variable is that the word 'independent' is a longer word and therefore 'sinks' to the bottom axis (the x axis)