A scatter graph is also known as a “scatter plot.” It displays a series of measured incidences of the correlation between two factors. One of these factors might be time-based. The observation displayed may be gained from one subject, or the results of a series of studies plotted together. A scatter graph typically has a vertical and horizontal axis, often labelled "x" and "y." The level of “x” at point ”y” is marked on the graph with a dot for each observation. Writing comments on graphs can confuse and obscure the data. Be careful how you annotate them.

Prepare the data without comments, either in a computer program, such a spreadsheet application, or on graph paper. Mark the scale on each axis clear and label each axis accurately. If you want to highlight relationships between observations in the series, use different coloured dots to mark each observation. Making the data clear reduces the need for notes on your graph, which is preferable.

Draw attention to any relationship between coloured groups of dots by writing a key on the graph. The key should lie in the top right hand corner of the graph, but only if there is no data falling in that region. If there are points plotted in that area, write the key below the graph, or to the right of the graph.

Write comments on a separate sheet that can overlay the graph. If you created your scatter graph on graph paper, overlay an “acetate,” or clear plastic sheet, and mark comments on that. You can write comments on several sheets and overlay them either together, or one at a time. If you created the graph in a computer package, extract an image of the graph into a slide in a presentation. Copy the picture onto several slides and then add comments to each version, leaving the first slide as the uncommented graph. This method provides a clean, uncrowded presentation of the raw data. It also enables alternative strategies, such as trend analysis and a notation of variance to highlight data without the confusion of overlaying comments.

Use different coloured text in the comments on the scatter graph making it clear which markers on the graph relate to which comments. Keep a separate sheet for each coloured category of comments so that they can also be viewed in isolation.

### Things you need

- Graph paper
- Acetate sheets
- Coloured pens

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