Ftest.Ttest: no visible binding for global variable ‘sd’
Ftest.Ttest: no visible global function definition for ‘pt’
Ftest.Ttest: no visible global function definition for ‘var’
Ftest.Ttest: no visible global function definition for ‘pf’
Ttest: no visible binding for global variable ‘sd’
Ttest: no visible global function definition for ‘pt’
do.one.experiment: no visible global function definition for
  ‘power.t.test’
do.one.experiment.t: no visible global function definition for
  ‘power.t.test’
optim.two.stage.appr: no visible global function definition for
  ‘mvrnorm’
optim.two.stage.appr: no visible global function definition for ‘var’
optim.two.stage.appr: no visible global function definition for ‘runif’
optim.two.stage.appr: no visible global function definition for ‘pbeta’
optim.two.stage.appr: no visible global function definition for ‘optim’
optim.two.stage.group: no visible global function definition for
  ‘mvrnorm’
optim.two.stage.group: no visible global function definition for
  ‘runif’
optim.two.stage.group: no visible global function definition for
  ‘pbeta’
optim.two.stage.group: no visible global function definition for
  ‘optim’
optim.two.stage.single: no visible global function definition for
  ‘mvrnorm’
optim.two.stage.single: no visible global function definition for
  ‘runif’
optim.two.stage.single: no visible global function definition for
  ‘pbeta’
optim.two.stage.single: no visible global function definition for
  ‘optim’
power: no visible global function definition for ‘par’
power: no visible global function definition for ‘hist’
power.appr: no visible global function definition for ‘qt’
power.appr: no visible global function definition for ‘pt’
power.appr: no visible global function definition for ‘var’
power.appr: no visible global function definition for ‘qf’
power.appr: no visible global function definition for ‘pf’
power.appr: no visible global function definition for ‘dt’
power.appr: no visible global function definition for ‘splinefun’
power.appr: no visible global function definition for ‘integrate’
power.group.cost: no visible global function definition for ‘mvrnorm’
power.group.cost : Ftest.Ttest: no visible binding for global variable
  ‘sd’
power.group.cost : Ftest.Ttest: no visible global function definition
  for ‘pt’
power.group.cost : Ftest.Ttest: no visible global function definition
  for ‘var’
power.group.cost : Ftest.Ttest: no visible global function definition
  for ‘pf’
power.group.cost : do.one.experiment: no visible global function
  definition for ‘power.t.test’
power.group.cost: no visible global function definition for ‘par’
power.group.cost: no visible global function definition for ‘hist’
power.single.cost: no visible global function definition for ‘mvrnorm’
power.single.cost : Ttest: no visible binding for global variable ‘sd’
power.single.cost : Ttest: no visible global function definition for
  ‘pt’
power.single.cost : do.one.experiment.t: no visible global function
  definition for ‘power.t.test’
power.single.cost: no visible global function definition for ‘par’
power.single.cost: no visible global function definition for ‘hist’
power.t: no visible global function definition for ‘par’
power.t: no visible global function definition for ‘hist’
Undefined global functions or variables:
  dt hist integrate mvrnorm optim par pbeta pf power.t.test pt qf qt
  runif sd splinefun var
Consider adding
  importFrom("graphics", "hist", "par")
  importFrom("stats", "dt", "integrate", "optim", "pbeta", "pf",
             "power.t.test", "pt", "qf", "qt", "runif", "sd",
             "splinefun", "var")
to your NAMESPACE file.