Moins de résultats en utilisant la troncature ? Pourquoi ?

The truncation character in ProQuest is an asterisk ()--used to replace up to five characters. For example, a search for farm will retrieve documents with the terms farm, farms, farmer, or farming. You can include the truncation character within a word in your search term, frm, or at the end of a word, (farm).
Extrait de la section Search Tips de la plateforme ProQuest

Certif includes: certify, certifying, certifies, certified, certificate, certifiable, certifiably
Certif does not include: certificates, certificated, certification, certifications
(slide 11)

PubMed’s Automatic Term Mapping applies to all “untagged”fields. It counts specifying [all fields] as an “untagged” field.
[...]
Adding quotation marks and/or truncating a term preventsthis in all databases [...]
(slide 12)

Extrait de l'aide de PubMed à la slide 8