Creating Effective Graphs
From Stepping Up
| Letting the Numbers Talk |
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In science, graphs are one of the main methods of presenting information effectively and concisely. Graphs usually represent quantitative results from your experiments in a visual way. A few graphs on your board will not only reduce the amount of text cluttering your board, it can also be visually appealing to your audience. But like many other things, don’t overdo it! Keep the number of graphs to a minimum.
Every graph should have:
- A TITLE that is easily located. The title should tell your audience what information the graph is trying to convey.
- LABELS on the axis, or in the form of a legend. A legend is a separate box near or on an empty part of your graph that clearly shows what each part of the graph represents, if there are multiple sections or sets of information.
- NUMBERS; remember, your graph is representing a quantitative information. Your graph should have numbers labeled on the axis, or in the case of pie charts, near each sections.
There are numerous types of graphs, and depending on what you use it for, there is often one type of graph that is the most effective and the most easily decoded by your audience for your purpose. Here, I will list the most commonly used types of graphs.
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Pie Chart
The purpose of a pie chart is to present information that is divided into different categories. It should be ordered from large to small sections, and should always have a legend to tell the audience what each of the sections represent. Its shape, a circle, offers a visual sense of a whole (100%) of something.
Bar Graphs
When you have only a few data points (10 or less), and want to visually emphasize the size of your numerical data (by the height of a bar), the bar graph would be the right type of graph to use. Bar graphs are also handy when you want to compare two different sets of data, because bar graphs allow you to plot more than one data set on one graph. It is important to label your axis and their respective increments, as well as a legend if there are more than one set of data represented.
Line Graphs
On a line graph, each value is represented by a data point. Line graphs are used when there are many data points, where each data point can be connected by a line, or a line of best fit can be drawn to show a trend. Like bar graphs, line graphs can have multiple sets of information, i.e. multiple lines on one graph.
Standard Deviation
Even if you try very hard to make your experiments precise, there is always a possibility of your data being not as precise as you hoped. This is accounted for by standard deviation. Standard deviation is the measure of dispersion of a data set. Sometimes, you are expected to include the standard deviation on your graph. They are represented by a small bar protruding from each data point (refer to figure 2, the bar graph). The calculation of the value of the standard deviation can be complicated; but do not worry! The Excel program can do all that for you.
Make sure to see: More than Just the Mean
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