The phrase "questionable conclusion" is correct and can be used in written English.
It refers to a statement or belief that is uncertain or doubtful in its validity or accuracy. Example: The study's methodology was flawed and therefore the researchers' questionable conclusion must be taken with a grain of salt.
Mr. Griffiths's article on a score of Mahler's First Symphony discovered in Israel draws questionable conclusions, especially his assertion that the corrections were written by Mahler.
These days, "bad" parenting (not the orphanage-style bad but your garden-variety kind) is also linked via studies with questionable conclusions to stunted brain development.
Morris Busby, who became the American ambassador shortly after the report was written and said he did not remember it, cautioned that some of the reports collected by intelligence agencies came to questionable conclusions.
While they didn't provide definitive answers, the e-mails provided more than enough breadcrumbs to feed reporters, as well as conspiracy theorists who followed every stray reference, sometimes to questionable conclusions.
But some of these studies – pushing results too far – have come up with questionable conclusions.
The values of ɛs, ɛ∞ and tan δ measured are not the true values of the sample and their analysis leads to questionable conclusions.
The allegation has many in the US - and Pakistan - crying foul, and pointing to what they see as insufficient attribution and questionable conclusions throughout Hersh's lengthy piece.
This week, Google started to propose a second line of attack to try to raise the level of conversation around questionable content: it plans to post alternative viewpoints and information, sourced from Wikipedia, alongside videos that carry questionable conclusions, for example conspiracy theories (although it's not clear how Google will determine which videos are conspiracies, and which are not).
What I do take exception to is those organizations making statements about their work designed to lead to questionable conclusions.
