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General
These guidelines are written for hand drawn graphs but most of the points are applicable to computer-generated graphs. These guidelines are used in teaching Biology in Tasmania.
Graphs are used to
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Communicate information to other people.
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Identify trends in different variables (interpretation)
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Identify how one factor affects another (correlation)
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Help understand what the data represents (analysis)
Graphing data
General
A graph shows the relationship between two quantities in a way that is
easily understood. It is important that graphs should be plotted
accurately and the data presented be easily interpreted. The following
points should be noted:
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(i) The independent variable (manipulated variable) is the factor
that is specifically varied in an experiment. It usually changes in a
regular manner, for example time or temperature. This factor is plotted
along the horizontal (x) axis of the graph
(ii) The dependent variable (responding variable) is the response
observed (measurements made) when the independent variable is altered.
Such values 'fluctuate' during an experiment, for example rate or
frequency. This factor is plotted along the vertical (y) axis of the
graph.
A typical graph has the following features;
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Entire graph including labelling should be done with a sharp pencil.
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Select the appropriate form of graph (e.g. point graph, column graph or histogram) according to the data.
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Axes must be drawn with a ruler and have labels which should include units where appropriate.
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The axes must be calibrated evenly and where the scale does not go to 0, use a broken axis, . Tick marks should be included where values are shown.
Equal intervals on he scale must represent equal numerical values.
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Choose a scale which uses the graph paper to the full. Centre the graph on the paper.
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The whole graph should be clear and neat.
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The graph must have a title which refers to the labels given to the horizontal and vertical axes (usually the independent and dependent variables.)
Provide an explanatory title for the graph.
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Data Analysis
Organisation
of Data
Drawings
Tabulating info
Graphing
Line graphs
Column graphs
Histograms
Scatter graphs
Two+
variables
Summary
Analysis of Data
Trends
on a graph
Guidelines from BIOTA
Report Writing
Working Scientifically
Observations
Observation Questions
Hypothesis Formation
Experimental Design
Aspects
Ethics
Types of Research
Data Analysis |
