coef.frontier: no visible global function definition for 'pnorm'
coef.frontier: no visible global function definition for 'dnorm'
efficiencies.frontier: no visible global function definition for
  'residuals'
efficiencies.frontier: no visible global function definition for 'coef'
efficiencies.frontier: no visible global function definition for
  'pnorm'
efficiencies.frontier: no visible global function definition for
  'dnorm'
elas.frontierQuad: no visible global function definition for 'coef'
elas.frontierQuad: no visible global function definition for 'vcov'
front41WriteInput: no visible global function definition for
  'write.table'
frontier: no visible global function definition for 'as.formula'
logLik.frontier: no visible global function definition for 'coef'
logLik.frontier: no visible global function definition for 'logLik'
lrtest.frontier: no visible global function definition for 'logLik'
lrtest.frontier: no visible global function definition for 'pchisq'
lrtest.frontier: no visible binding for global variable
  'lrtest.default'
print.front41Output: no visible global function definition for 'coef'
print.frontier: no visible global function definition for 'coef'
print.summary.front41Output: no visible global function definition for
  'printCoefmat'
print.summary.front41Output: no visible global function definition for
  'coef'
print.summary.frontier: no visible global function definition for
  'printCoefmat'
print.summary.frontier: no visible global function definition for
  'coef'
sfa: no visible binding for global variable 'na.pass'
sfa: no visible global function definition for 'model.matrix'
sfa: no visible global function definition for 'model.response'
sfa: no visible global function definition for 'lm'
sfa: no visible global function definition for 'coef'
sfa: no visible global function definition for 'vcov'
sfa: no visible global function definition for 'logLik'
sfa: no visible global function definition for 'residuals'
summary.front41Output: no visible global function definition for 'pt'
summary.front41Output: no visible global function definition for
  'pnorm'
summary.frontier: no visible global function definition for 'pt'
summary.frontier: no visible global function definition for 'coef'
summary.frontier: no visible global function definition for 'vcov'
summary.frontier: no visible global function definition for 'pnorm'
summary.frontier: no visible global function definition for 'residuals'
vcov.frontier: no visible global function definition for 'coef'
Undefined global functions or variables:
  as.formula coef dnorm lm logLik lrtest.default model.matrix
  model.response na.pass pchisq pnorm printCoefmat pt residuals vcov
  write.table
Consider adding
  importFrom("stats", "as.formula", "coef", "dnorm", "lm", "logLik",
             "model.matrix", "model.response", "na.pass", "pchisq",
             "pnorm", "printCoefmat", "pt", "residuals", "vcov")
  importFrom("utils", "write.table")
to your NAMESPACE file.