help xtfrontier dialog: xtfrontier also see: xtfrontier postestimation -------------------------------------------------------------------------------
Title
[XT] xtfrontier -- Stochastic frontier models for panel data
Syntax
Time-invariant model
xtfrontier depvar [indepvars] [if] [in] [weight] , ti [ti_options]
Time-varying decay model
xtfrontier depvar [indepvars] [if] [in] [weight] , tvd [tvd_options]
ti_options description ------------------------------------------------------------------------- Model i(varname_i) use varname_i as the panel ID variable noconstant suppress constant term ti use time-invariant model; the default cost fit cost frontier model constraints(constraints) apply specified linear constraints
SE vce(vcetype) vcetype may be bootstrap or jackknife
Reporting level(#) set confidence level; default is level(95)
Max options ml_maximize_options control the maximization process; seldom used -------------------------------------------------------------------------
tvd_options description ------------------------------------------------------------------------- Model i(varname_i) use varname_i as the panel ID variable t(varname_t) use varname_t as the time variable noconstant suppress constant term tvd use time-varying decay model cost fit cost frontier model constraints(constraints) apply specified linear constraints
SE vce(vcetype) vcetype may be bootstrap or jackknife
Reporting level(#) set confidence level; default is level(95)
Max options ml_maximize_options control the maximization process; seldom used -------------------------------------------------------------------------
You must tsset your data before using xtfrontier; see tsset. depvars and indepvars may contain time-series operators; see tsvarlist. fweights and i weights are allowed; see weight. bootstrap, by, jackknife, statsby, and xi may be used with xtfrontier; see prefix. See xtfrontier postestimation for features available after estimation.
Description
xtfrontier fits stochastic production or cost frontier models for panel data. More precisely, xtfrontier estimates the parameters of a linear model with a disturbance generated by specific mixture distributions.
The disturbance term in a stochastic frontier model is assumed to have two components. One component is assumed to have a strictly non-negative distribution, and the other component is assumed to have a symmetric distribution. In the econometrics literature, the non-negative component is often referred to as the inefficiency term, and the component with the symmetric distribution as the idiosyncratic error. xtfrontier permits two different parameterizations of the inefficiency term: a time-invariant model and the Battese-Coelli parameterization of time-effects. In the time-invariant model, the inefficiency term assumed to have a truncated-normal distribution. In the Battese-Coelli parameterization of time effects, the inefficiency term is modeled as a truncated-normal random variable multiplied by a specific function of time. In both models, the idiosyncratic error term is assumed to have a normal distribution. The only panel-specific effect is the random inefficiency term.
Options for time-invariant model
+-------+ ----+ Model +------------------------------------------------------------
i(varname_i); see estimation options.
ti specifies that the parameters of the time-invariant technical inefficiency model be estimated.
noconstant; see estimation options.
cost specifies the frontier model be fitted in terms of a cost function instead of a production function. By default, xtfrontier fits a production frontier model.
constraints(constraints); see estimation options.
+----+ ----+ SE +---------------------------------------------------------------
vce(vcetype); see vce_option.
+-----------+ ----+ Reporting +--------------------------------------------------------
level(#); see estimation options.
+-------------+ ----+ Max options +------------------------------------------------------
ml_maximize_options: difficult, technique(algorithm_spec), iterate(#), [no]log, trace, gradient, showstep, hessian, shownrtolerance, tolerance(#), ltolerance(#), gtolerance(#), nrtolerance(#), nonrtolerance, from(init_specs); see ml and maximize. These options are seldom used.
Options for time-varying decay model
+-------+ ----+ Model +------------------------------------------------------------
i(varname_i), t(varname_t); see estimation options.
noconstant; see estimation options.
tvd specifies that the parameters of the time-varying decay model be estimated.
cost specifies the frontier model be fitted in terms of a cost function instead of a production function. By default, xtfrontier fits a production frontier model.
constraints(constraints); see estimation options.
+----+ ----+ SE +---------------------------------------------------------------
vce(vcetype); see vce_option.
+-----------+ ----+ Reporting +--------------------------------------------------------
level(#); see estimation options.
+-------------+ ----+ Max options +------------------------------------------------------
ml_maximize_options: difficult, technique(algorithm_spec), iterate(#), [no]log, trace, hessian, gradient, showstep, shownrtolerance, tolerance(#), ltolerance(#), gtolerance(#), nrtolerance(#), nonrtolerance, from(init_specs); see ml and maximize. These options are seldom used.
Examples
. xtfrontier lnv lnk lnl, i(id) t(t) tvd
. xtfrontier lnv lnk lnl, i(id) ti
. xtfrontier lnv lnk lnl, i(id) t(t) tvd cost
Also see
Manual: [XT] xtfrontier
Online: xtfrontier postestimation; frontier, regress, tsset, xtreg