Anecdotal

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

if true—and it appears consistent with anecdotal information—about 50 regime figures have been killed this year.
why north korea released two americans gordon g. chang november 8, 2014

until recently, the dominant paradigms for both lie detection and interrogation were based mostly on anecdotal police evidence.
new research suggests enhanced interrogation not effective r.m. schneiderman may 24, 2012

but they do say that, even if all of their evidence (so far) is anecdotal.
new york’s nanny-state e-cig ban olivia nuzzi december 19, 2013

the “link” consists in anecdotal reports that some people think kids with autism improve on a dairy-free diet.
twisted anti-vaxxer parents choose fatal diseases over autism elizabeth picciuto june 30, 2014

most of the information on this topic is anecdotal, if consistent: bad economic times pretty much guarantee bad s-x.
when markets fall, so do the big swinging d-cks mimi swartz october 16, 2008

historical examples

like the two older pyramids, “the supreme” had its anecdotal history, in which the egyptians gave free rein to their imagination.
history of egypt, chalda, syria, babylonia, and -ssyria, volume 2 (of 12) g. maspero

you say that the sensualities of princes are only of ‘anecdotal interest.’
the catholic world, vol. x, october 1869 various

whilst i am anecdotal, perhaps i had better say something about books into which my stories have been pressed.
the reminiscences of an irish land agent s.m. hussey

they represent the interest of the century in fiction and in anecdotal literature.
the thirteenth james j. walsh

if an anecdotal review is bad, it is because it is badly done, not because it is anecdotal.
the art of letters robert lynd

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.