applyMetaCheck: no visible global function definition for
  'globalVariables'
computeCfvar: no visible global function definition for 'sd'
computeLag: no visible global function definition for 'tail'
computeLag: no visible global function definition for 'head'
computeMedian: no visible global function definition for 'median'
computeSd: no visible global function definition for 'sd'
computeVariance: no visible global function definition for 'var'
enter: no visible global function definition for 'lm'
enter: no visible global function definition for 'as.formula'
xpssCorrelations: no visible global function definition for 'na.omit'
xpssDescriptives: no visible global function definition for 'na.omit'
xpssDescriptives: no visible global function definition for 'sd'
xpssDescriptives: no visible global function definition for 'var'
xpssFrequencies: no visible binding for global variable 'frequency'
xpssFrequencies: no visible global function definition for 'na.omit'
xpssFrequencies: no visible global function definition for 'quantile'
xpssFrequencies: no visible global function definition for 'var'
xpssFrequencies: no visible global function definition for 'density'
xpssFrequencies: no visible global function definition for 'lines'
xpssFrequencies: no visible global function definition for 'title'
xpssFrequencies: no visible global function definition for 'median'
xpssFrequencies: no visible global function definition for 'sd'
xpssMeans: no visible global function definition for 'na.omit'
xpssMeans: no visible global function definition for 'summary.lm'
xpssMeans: no visible global function definition for 'anova'
xpssRegression: no visible global function definition for 'na.omit'
xpssRegression: no visible global function definition for 'anova'
xpssRegression: no visible binding for global variable 'sd'
xpssTtest: no visible global function definition for 'complete.cases'
xpssTtest: no visible global function definition for 't.test'
xpssTtest: no visible global function definition for 'na.omit'
xpssTtest: no visible global function definition for 'sd'
xpssTtest: no visible global function definition for 'var'
xpssTtest: no visible global function definition for 'cor.test'
Undefined global functions or variables:
  anova as.formula complete.cases cor.test density frequency
  globalVariables head lines lm median na.omit quantile sd summary.lm
  t.test tail title var
Consider adding
  importFrom("graphics", "lines", "title")
  importFrom("stats", "anova", "as.formula", "complete.cases",
             "cor.test", "density", "frequency", "lm", "median",
             "na.omit", "quantile", "sd", "summary.lm", "t.test", "var")
  importFrom("utils", "globalVariables", "head", "tail")
to your NAMESPACE file.