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10 Tips for

Better Visualization of

Scientific DataSercan Taha Ahi (tahaahi@gmail.com)

Yamaguchi Laboratory @ Tokyo Institute of Technology

2012/7/26

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Each plot, each figure, and each drawing is there to communicate a

scientifically interesting idea to a scientific community.

They are not intended to be laundry lists of experimental outcomes.

Please do not forget the purpose, and do not forget the audience.

Before starting

36%

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1. Get rid of “empty” dimensions.

A pie chart

A better pie chart

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A bar graph

A better bar graph

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2. Maximize data-ink ratio.

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A bar graph A better bar graph

Optimized data-ink ratio (1) is eco-friendly, (2) provides better visibility - even for greyscale prints-, and (3)

communicates ideas more efficiently.

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3. Show the entire scale.

Is this a significant drop?

A line plot A better line plot

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3. Show the entire scale.

This one is better

A group of line plots

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4. State the axis labels, units, and title.

A line plot A better line plot

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100Classification accuracy

Number of training samples

Acc

ura

cy (

%)

For arbitrary units, use (a.u.)

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5. Set the aspect ratio appropriately.

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2-dim representation of the data by PCA

PC#1

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#2

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2-dim representation of the data by PCA

PC#1

PC

#2

A 2D plot

A better 2D plot

Although the ranges of x and y coordinates of the

data samples are unequal, the left figure has equal

length x and y axes, which might mislead the viewer

into believing the distance between cluster A and B is

equal to the distance between cluster A and C.

A

B

C

A

B

C

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6. Indicate and label uncertainty.

There is an uncertainty in every experiment, in every measurement. Depending on the deviation in the data,

the conclusions that you draw might be drastically different. Therefore, you should always show the

uncertainty in the data.

Mean plot

Mean plot

One data sample

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Wavelength (nm)N

orm

aliz

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coeffi

cien

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a.u

.)

(Given confidence intervals are for 1 std.)

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Wavelength (nm)

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a.u

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7. Do not use bitmap graphics; prefer eps or pdf when possible.

Bitmap graphics do not scale well. When graphics do not scale well, your study looks amateurish.

Use vector graphics instead. If you have no access to proprietary tools, then please create high-resolution

bitmap images, or better, consider using free programming languages such as R and Python for plots, and

free graphics tools such as Inkscape and Gimp for drawings.

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100Classification accuracy

Number of training samplesA

ccura

cy (

%)

A line plot A better line plot

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8. Set the precision of the real numbers appropriately.

0.060216

612.272794

1224.510995

1836.737045

2449.010718

3061.264419

3673.485352

4285.764609

4897.965173

5510.240014

6122.491553

6734.756012

7346.954305

7959.213265

8571.479209

9183.700827

9795.935226

0

0.3235235

0.647047000000001

0.970570500000001

1.294094

1.6176175

0.060216

408.193666

816.356831

1224.510995

1632.684048

2040.827888

2449.010718

2857.165282

3265.318728

3673.485352

4081.650341

4489.808321

4897.965173

5306.167373

5714.313701

6122.491553

6530.654041

6938.789245

7346.954305

7755.141964

8163.295462

8571.479209

8979.635357

9387.81045

9795.935226

0.00.20.40.60.81.01.21.41.61.8

A line plot

A better line plot

Ask yourself: What is the minimum precision (number of decimal places) needed to convey my idea?

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9. Choose colors carefully.

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Our methodTheir method1Their method2Their method3Their method4

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A bar graph A better bar graph

When you want to compare your method with a number of well-established approaches on a graph, pick an

easily distinguishable color for your results. Do not make the listeners or readers search for it.

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9. Choose colors carefully.

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A scatter plot A better scatter plot

Be gentle, and do not forget color blinds.

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10. Put your data into a context.

A plot that depicts the total snowfall in Boston for the winter of 2010-2011

Inches?? Can you quickly imagine how high 80.1 inches is?

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10. Put your data into a context.

A better plot that depicts the total snowfall in Boston for the winter of 2010-2011

Now you can, right?

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THANK YOU.I would also like to thank Dr. Mehmet Cagatay

Tarhan for his valuable comments.