What Makes a Good Graph

** YOUR GRAPH TELLS A STORY, IT SHOULD STAND ALONE AND A STRANGER SHOULD BE ABLE TO LOOK AT IT AND UNDERSTAND THE

“STORY” BEING TOLD. **

2010 – Collecting Data

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1. NEATNESS COUNTS

• use a pencil!, graph paper, a ruler to produce neat, accurate graphs (colors are nice!)

• Easy to read easy to grade!!

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2. Must have a TITLE• Descriptive title - Always give your graph a title in the

following form: "The dependence of (your dependent variable) on (your independent variable).

• Let's say that you're doing a graph where you're studying the effect of temperature on the speed of a reaction. In this reaction, you're changing the temperature to known values,

• temperature is your independent variable. • Because you don't know the speed of the reaction and

speed depends on the temperature, the speed of the reaction is your dependent variable.

• As a result, the title of your graph will be "The dependence of reaction rate on temperature"

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3. What are your AXES

• Y (vertical axis): dependent variable → measures or frequency (i.e. counts, %) dependent variable changes or is manipulated

• X: (horizontal axis): independent variable →

distribution (i.e. time, categories)

• For the graph described above, temperature would be on the x-axis (the one on the bottom of

the graph), and the reaction rate would be on the y-axis (the one on the side of the graph)

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4. What are your UNITS?

• Y and X are uniform / uncluttered, having units and labels

• If you don’t have units we do not know what you are talking about!!

• Proper Scale (0,5, 10, 15)not ( 2, 10, 22, 30)

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5. Key and Legend

• Key to identify your sets of Data• Legend to tell: who, what, when, where, and

how

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Line Graphs

Visually displays values, usually over time to show trends

Best way to plot multiple sets of data for comparison

Implies continuous data (i.e. time)** Best Choice **

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Bar Graphs

Emphasizes magnitudes more than percentages or differences

Can plot multiples sets of data (series) for comparison

Implies discrete data (i.e. letter grades, hair color)

Best for comparing categories

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Pie GraphsCompares relative magnitudes or frequencies Can plot only a single set of data Shows the percentage an item contributes to

the whole

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Grades vs. hours of sleep for two science clasesat Charles W. Flanagan High School, Pembroke

Pines, FL, 2002

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What is Wrong With this Graph?

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What is Should Look Like

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