A data page will open. There are “data pages” (pages of tables) and “chart pages” that are pages with graphs on them.
Enter data (going downwards will be “x” axis, across will be “z” if you have 2-variable design)
Consider, for example
Study on Perceived values of numbers (with Johanna)
Asked subjects to judge “how good” (on likert scale) different proportions would be, in specific contexts (a grade of 8/10, a grade of 80/100).
Scale (10, 100, 1000)
Context (grades, toothpaste, cancer, profits)
We want to plot perceived goodness as a function of proportion and scale for each context (4 different graphs)
First thing we do is enter our data (this is like a cooking show). We have different tables for each context (Data pages). Use table icon to go to new data page. Name each page so you know what context it is. (to name page, click on “view” on menu then go to “name page”)
Making a graph
Highlight data you want to graph
Click on “data” on menu page and go to “Chart Gallery”
Choose a chart (line graph)
A graph will automatically be created with certain defaults on a new “chart page”
Name the chart page by going to “view” and “name page”
Changing features of our graph
Click on “text box” to add text
Using the chart menu
Go to “axes” to change scale or start point, etc.
Use “labels” to label “x” and “y” axes
Use “ticks and grids” to change where your ticks are, and whether or not you have grids
Use toolbox on left to change colors, patterns, add text, draw anything, etc.
Change size by pulling on corner; move
Making a new graph exactly the same
Go to “file” menu to open up a new library
Drag your graph into the library and name it (you can either save as template or save w/ data). Save as template
Now, drag the template back to your chart page (if you want it on the same page). Or, open new chart page by clicking on graph icon and “new page”
It will now go to the original data page.
Making new graph continued
Now, go to a new data page (let’s look at breast cancer page). Highlight the data you want to graph.
Click on plot.
Now a graph with same size and features appears on the page (you may have to make some changes, such as scale or labels, depending on data)
Tips for creating good graphs
Communicate relevant information explicitly (think: What do I want to convey). Remember, different graphic formats highlight different information about the same complex data. Consider the following examples:
Look at this graph
Compared to this one
Or this one
Compare this graph
Use line graphs for conveying trends (graphic convention is to only use for continuous data, but I violate that to make my point sometimes)
Bar graphs to make categorical comparisons
3-d graphs if exact data isn’t important, but a complex relationship or some idiosyncratic data points are important.
Pie charts are not good for exact values, good for comparing proportions.
Avoid forcing the reader to make any “calculations” or complex inferences
Do not make them mentally change scale
Do not make them subtract everything from 100 (e.g. if you’re talking about error data in the graph and accuracy data in your paper)
Do not make them subtract values on one graph from another graph on a different page!!
Keep it simple
Remember, adding 3d is not always so good. You lose ability to read exact data points, and you can occlude important data.
Lots of colors and designs are cool, but not necessarily helpful
Label your lines, avoid using legends
Make your symbols or lines distinct if they are to be compared. Esp if data are complex!
And plot only what you want to show
If the 1000’s scale doesn’t matter, don’t plot it
If the important thing is the relative values of different contexts, plot those four averages in a single bar graph. Leave out the other variables
Goal of graph reader
Expertise of the graph reader
Consider some bad graphs
Like this 3d graph of our proportion judgment study
Using graphs for more
Exploratory data analysis
Many statistical software packages allow you to make simple graphs to look at your data.