Anecdotally

pertaining to, resembling, or containing :
an anecdotal history of jazz.
(of the treatment of subject matter in representational art) pertaining to the relationship of figures or to the arrangement of elements in a scene so as to emphasize the story content of a subject.
compare (def 6).
based on personal observation, case study reports, or random investigations rather than systematic scientific evaluation:
anecdotal evidence.
contemporary examples

anecdotally, crime is slightly down in ferguson since brown died, decarli said.
ferguson’s only unsolved murder justin glawe october 19, 2014

anecdotally, some babies are ‘never the same’ after vaccines.
from ‘clueless’ to clueless: alicia silverstone’s ‘the kind mama’ lizzie crocker april 21, 2014

anecdotally, the influx of immigrants from latin america and east asia seems to have strengthened latino and asian ident-ties.
how ethnic can our politicians be? reihan salam june 10, 2010

“anecdotally i can tell you that the take-up rate is fairly small,” said smyth.
walmart’s new embrace of gay employees a sign of corporate shift daniel gross august 28, 2013

“anecdotally, we have u.s. citizens who smuggle drugs, in large amounts sometimes,” he says.
at mexican border, four in five drug busts involve american citizens andrew becker, g. w. schulz, tia ghose march 25, 2013

historical examples

instruction must be carried on objectively, experimentally, anecdotally.
talks to teachers on psychology; and to students on some of life’s ideals william james

adjective
containing or consisting exclusively of anecdotes rather than connected discourse or research conducted under controlled conditions
adj.

1794, from anecdote + -al (1). related: anecdotally. anecdotical is attested from 1744.