SO YOU WANT TO MAKE A GRAPH Name ________________________________________ Date __________________ Period ___________ SO YOU WANT TO MAKE A GRAPH Ah, Graphing. What a noble pursuit! I’m so delighted that you’ve decided to take part in this wonderful tradition, and make a graph of your own. Below, you’ll find a few things that will be very useful to you as you craft your graph, so pay attention! The purpose of a graph is to: Present data in a format that is easy to understand. Form a logical, cause-and-effect connection between two sets of data. If, when you are done with your graph, it doesn’t do either of these things, go back and try again. You should make sure that you follow all the guidelines below to create the best graph possible. I. Use a ruler to construct your axes – This means that you should use a ruler. Alternately, use a computer, which must have a ruler in it somewhere, because the lines they make are always straight… II. Label everything you can – That means I want a label on each axis, a title on the top, and a legend or key of some sort that tells me what is going on. Make it clear and concise! III. UNITS! – Tell me what units are used on each axis. You don’t have to put units on every single number, but just in the axis label (see example). IV. Connect the Dots – This is tricky, and if you don’t read this, you may become easily confused. If your data is solid and will never, ever, ever change, you can connect each dot with a ruler. That is, if you have taken data every second for three hours, and you know the data exactly, you can use a straight line to connect all the points. But if you have taken just a few measurements, and you have large gaps between your data points, DO NOT connect the points with a ruler. Use a best-fit line (see example). The point of a best fit line (best constructed by a computer, but you can do one too – just draw a line with a ruler that is about the same distance away from each point) is to point out a general trend in your data. You might be able to see if the relationship is direct or indirect much easier with a best-fit line than without. Obviously, if you’re making a bar graph or histogram, there are no dots. So just make sure your bars are neat and end where they are supposed to. V. Variables – Put the variables on the correct axis. The independent variable is the thing that you manipulate in the experiment, and is usually time, distance, etc. It can be something like the amount of fertilizer that you add to a plant, or the dosage of a new drug. This goes on the X axis, an nowhere else. The dependent variable is the one that “depends” on the independent one. That is, it changes as the independent variable does. It is what you are experimenting with, it’s the “Why” in your experiment. It goes on the Y axis, and nowhere else. If your graph was of the effect of temperature on reaction rate, then the temperature is what you are changing (independent variable, X axis), and the reaction rate is what you are looking for (dependent variable, Y axis). VI. Neatness and Readability – Do not turn in graphs that are wrinkled, smudged, erased, white-out-ed, or otherwise un-neat. If you are using a computer, do not choose backgrounds, colors, patterns, outlines, fonts, etc. that interfere with the readability of your graph. For instance, a light blue line on a light blue background with light blue points will probably not be very helpful to your reader. You should make your

graph attractive and eye-catching, but don’t make it complicated and difficult to read. Pay special attention to the fonts that you use and how easy they are to read. VII. Example – Note how this example has data points that are fairly spread out, so the points are not connected by a line, but rather, a best-fit line has been inserted. There are titles and labels with units where appropriate, and the variables are on the correct axes. The trend of the data is easily sussed out and, while it is sad and/or slightly depressing, the story that the graph tells is quite easy to read. Figure 1. A rather sad but still accurate and well-drawn graph.