Cambridge Pre-U Syllabus - Cambridge International Examinations

50
Cambridge Pre-U Draft
Sub-skill
Presenting data in the form of graphs and charts
Candidates should be able to:
• present data in the form of charts, graphs, drawings or mixtures of methods of presentation
• select the most appropriate form of presentation for the data collected or provided, e.g. bar chart,
histogram and line graph
• select which variable(s) to plot and plot appropriately on clearly labelled x- and y-axes
• plot all points or bars to an appropriate accuracy
• follow the Society of Biology recommendations for putting lines on graphs.
Generally, candidates are expected to present data in the form in which the key points of the data can be
most easily visualised:
for quantitative data, this is likely to be a graph,
for qualitative data this may be a table.
Candidates should:
choose scales for the graph axes that allow the graph to be read easily, such as 1, 2 or 5 units to a
20 mm square;
make the best use of the space available, using over half of the length and width of the grid;
use pencil for lines on graphs.
The accepted scientific conventions for labelling the axes of a graph are the same as for the column
headings in a table of results with both the quantity and the unit shown (where appropriate). Points should
be finely drawn with a sharp pencil, but must still be visible. A fine cross or an encircled dot is suitable; a
thick pencil blob is not. Often it is obvious that the data fall on a straight line or smooth curve, when a line of
best fit or appropriate curve should be placed on the graph. Sometimes it is not possible to be sure if the line
should be straight or a smooth curve, so adjacent points should be joined by straight ruled lines in order to
represent the data with the minimum of assumptions. Lines of best fit should show an even distribution of
points on either side of the line along its whole length. Lines should be finely drawn and should not contain
kinks or breaks. If error bars are placed onto graphs, then the line of best fit must go through those error
bars.