Stata now handles factor (categorical) variables elegantly. You can now prefix a variable with i. to specify indicators for each level (category) of the variable. You can put a # between two variables to create an interaction–indicators for each combination of the categories of the variables. You can put ## instead to specify a full factorial of the variables—main effects for each variable and an interaction. If you want to interact a continuous variable with a factor variable, just prefix the continuous variable with c.. You can specify up to eight-way interactions.
We run a linear regression of cholesterol level on a full factorial of age group and whether the person smokes along with a continuous body mass index (bmi) and its interaction with whether the person smokes.
You can now include multiple fonts in regular, bold, and italics; the full Greek alphabet in upper- and lowercase; and over 70 mathematical symbols anywhere that text appears in graphs.
Graphs now accept an extended version of Stata’s text markup language, SMCL. Greek letters and mathematical symbols have intuitive, easy-to-remember names (tags). To make the title of the x axis of your graph say “β-carotene”, you just specify xtitle(“{&beta}-carotene”). To include χ2 in your text, specify {&chi} {superscript:2} or, even shorter, {&chi}{sup:2}. Additional tags make it easy to select from among sans serif, serif, monospace, and symbol fonts.
Here are a few other examples. Click on them to enlarge them.
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Of course, these new features are also available via the dialog boxes and through the interactive Graph Editor.
Here is a complete list of what’s new in Stata graphics: