Appendix A: Graphing
For graphic
presentation of results, the following rules should be observed:
Line graphs show changes in quantity of the dependant
variable and emphasize the rise and fall of the values over their range. Use a
line graph to present continuous data. When drawing best-fit lines, you do not have to go through any of the
points.
If you are
plotting more than one curve, the data point from each curve should be plotted
with different symbols.
BAR
GRAPHS are constructed
like line graphs except that a series of vertical bars are drawn from the datum
to the x-axis. Bar graphs are often used for data that represent separate or
discrete groups. For example, the graph to the right illustrates the
differences in height of males and females in Biology 111.
Note that
categories on the x-axis (bins) are separated by some space, i.e. there are
eight bars on this graph, though they are presented in four groups of two.
Appendix B: Captions
The amount of
information in a caption is context sensitive, but is usually more than most
students think. The caption for a graph will have different information than
that for a map; however, the caption’s job is to explain to the reader what is
illustrated; we do not use the word “title” synonymously with “caption”.
·
A key
to symbols is sometimes in the caption (if not, there would be a legend with
the same information)
A
map of… A
table of…
A
diagram of… A
graph of…
If
it isn’t obvious to the reader that you’re illustrating a map (for example),
without being told that this is “A map of…”, then the reader is not qualified
to read this material.
i.
microscope
images or drawings
·
type
of preparation
·
e.g.
whole mount, wet mount, section [which plane], smear
·
key
to symbols (if necessary)
·
species
ii.
graphs
·
error
bar interpretation (e.g. standard deviation, 95% Confidence Limit…), if
necessary
·
sample
size (this is sometimes placed elsewhere on the graph)
iii.
tables
·
sample
size
·
the
column heading of tables usually allow for easy interpretation, so little more
than a standard description is needed
If there are two graphs or pictures which are closely related, they
should appear within one figure, with
the two being labelled (a) and (b); one caption is used to refer to both.
For example, students were asked to measure the length
of two axes on scallops. This was done to determine if the height and length of
the shell grow uniformly relative to one another. The data are shown below,
with a single, suitable caption covering both graphs.
[1] To
avoid generating graphs with wasted space, you may signify unused graph space by
two vertical tic marks between zero and the lowest number on one or both axes,
or simply start the labelling of each axis at a higher number.