help paragr-------------------------------------------------------------------------------

Title

paragr-- Parallel graphing of a coefficient across different equations

Syntax

paragrvariable[,options]

Description

paragrprovides a fast and easy way to compare a coefficient across different equations within an estimation.It can used to visualize the parallel assumption of ordered logit or the equality of coefficients for quantile regression, etc.

By default

paragrplots a scatter graph. A quadratic fitted line (qfit) can be superimposed.Twoway graph options can be specified for the entire graph, or separately for the scatter graph or for the qfit graph.

Options+------+ ----+ Main +-------------------------------------------------------------

scatter()standard options for scatter graph. Use this to set color, range, etc

qfita quadratic fitted line is superimposed.

qfit()standard options for qfit graph. Use this to set color, range, etc

gen()a prefix for saving the plot points as variables.click here for a list of twoway options, including:

nodrawsuppress the display of graph

saving()save as a Stata graph

name(name[,replace])specifies the name of the graph

Examples* reg3 sysuse auto, clear reg3 (price weight rep78) (price weight rep78 mpg) (price weight rep78 mpg headroom) (price weight rep78 mpg headroom length) paragr rep78, xtitle(Equation) gen(reg3_) saving(mygraph)

* sqreg sysuse auto, clear sqreg price mpg rep78 headroom length, q(.10 .20 30 .40 .50 .60 .70 .80 .90) reps(25) paragr rep78, qfit

* Unconstrained gologit sysuse auto, clear egen money=cut(price), group(5) gologit money headroom mpg weight length turn displacemen paragr displacement

* constrained gologit2 from ssc (need Stata 8.2 or better) sysuse auto, clear egen money=cut(price), group(5) gologit2 money headroom mpg weight length turn displacement, auto paragr weight, qfit ytitle(odds ratios) xtitle(cut)

Remarks

qfitrequires at least two equations.Coefficient values goes on the y-axis.

AcknowledgementNick Cox provided detailed and helpful suggestions.

AuthorRoy Wada roywada@hotmail.com