Screening Survey for Early Vocabulary

"The average child will know 150 of the words in the Language Development Survey but scores of 75 to 225 are normal. 
Many late-talkers are simply late bloomers, so the professor says that if a child is otherwise developing normally, parents shouldn’t panic. 
But if the child is still struggling for words by two and a half, they should consider help such as speech therapy, and certainly not put this off past the age of three."

@ Mail Online Science & Tech