install.packages('irt')Itempool-class objectItempool-class object into a data.frame.Item, Itempool or Testlet objects and
return an Itempool object.Item-class objectItem-class,
Itempool-class or Testlet-class object.Item objectTestlet-class objectItem-class object.Item-classItem-class object.Item objectItempool objectTestlet-class objectItempool objectItempool objectTestlet-class objectItempool objects.Itempool-class objectItempool-class objectItem-class objectItem-class objectItempool objectsTestlet-class objectItempool objectsTestlet-class object.