Incorrect spelling

Name(s): 
Inability to spell
Spelling disorder
Cacography
Incidence 
According to a 1992 UK survey of 1,000 people, only 1 in 6 adults could correctly spell six familiar words (necessary, accommodation, sincerely, business, separate, height). 1 in 10 of the adults tested failed to spell any of the six words correctly.
Type 
(E) Emanations of other problems