Twoway graphs (line & scatter)

So far the created graphs had one thing in common: One axis was always numerical and the other one was defined by a categorical variable

In some cases, you may have two numerical variables and are interested in how/ whether their values are related using

a scatter plot
a line plot

All twoway graphs share the same set of options twoway options - keep these in mind as many of them can also be used for other graph types like the coefplot


			* Twoway: Scatter plots
sysuse auto.dta, clear 

// Draws scatter plot (one dot per observation)
twoway scatter price weight 
// Shorthand
scatter price weight
// Change the symbol
twoway scatter price weight, msymbol(x) 
// Use style of Economist magazine
twoway scatter price weight, scheme(economist) 

// Add a line at a specific value (here: mean of price)
sum price 
sum weight
twoway scatter price weight, yline(6165.257) xline(3019.459)


			* Twoway: Line plots
clear 
set obs 100 
gen time=_n 
gen white_noise=rnormal()

// Connects dots sequentially; e.g. in financial economics, evolution over time 
twoway line white_noise time 

// Compare this to the scatter plot: plots each dot by itself to assess relationship between two variables
twoway scatter white_noise time 

// Similar plots to line plot: 
// Combination of scatter and line plot
twoway connected white_noise time 
// Line plot with shaded area underneath
twoway area white_noise time 
// Spike for each observation
twoway spike white_noise time