Certified vs Certificated
When is it appropriate to use certified vs certificated?
If a person has been trained in X skill and has acquired that skill, is that person certified or certificated?
For me, certified sounds more of a product or food while certificated sounds like formal education.
If it helps, the word I use will help to describe a person that can now do X job because they now have the knowledge and skills required for the job, but it is not something as formal as gaining a qualification from a university or something like that, indeed, it's a training of 16 - 32 days.
Solution 1:
When a verb has a companion verbed noun (anthimeria?), the forms can have different nuances. Note that verbed nouns tend to be informal (stickered, friended, SMSed etc), though some have become established (booked, experienced, etc).
For example, consider
stuck vs stickered: an apple that is stuck may be wedged somewhere or otherwise not easily removed, but an apple that is stickered is one that has a sticker pasted on it.
befriended vs friended: someone you befriend is a person you have made friends with - you might dine together, go shopping, work on projects together, and so on. On the other hand, if you say you've friended someone, you mean that you have them on your Facebook list of friends; you might not even know them personally or interact with them at all.
There may well be pairs in which the 'proper' verb is treated more literally while the verbed noun is more general, but I don't have any instances handy.
Here's my take (AuE, though AmE might differ) on the case you're asking about:
The common term is certify (see definition below). Saying that someone has been certified carries the implication that the person is competent in whatever the certificate endorses. Saying that they have merely been certificated emphasises the acquisition of the certificate but doesn't say anything about the competence that the certificate is supposed to endorse.
certify verb 4 : to recognize as having met special qualifications (as of a governmental agency or professional board) within a field 'agencies that certify teachers' - M-W
Solution 2:
I ran a COCA and BNC search on the string certified/certificated (noun). I'll list the three most common uses on each search and their frequencies.
certified
- COCA: certified teachers / mail / copy (171 / 168 / 149)
- BNC: certified copy / question / accountants (24 / 18 / 17)
certificated
- COCA: certificated staff / carrier / employees (5 / 2 / 2)
- BNC: certificated foundation / officers / notaries (3 / 3 / 2)
COCA contains 560 millions words; BNC, 100 million.
From this short analysis, it seems certified is used more often to describe non-humans than humans (if I may draw a clunky sounding distinction) but the high frequency of certified teachers compared with certificated officers or employees or notaries may tip the scales in certified's favour. It may also be the case that certified teachers is a designation particular to the US, and this nation-specific usage is driving the high COCA count.
For whatever its worth, if I, a native BrE speaker, were forced to choose between the two, certified sounds more natural.