Deila is keen to bolster his squad further but concedes finding the right men is proving tough.
Potential confounders also limit conclusions, as the authors concede findings could be due to emotional stress and potential impact of compensation bias in the test results.
MR. BARDY conceded that finding a strong international manager who will continue to beat the market is "impossible to do with certainty".
His biggest problem, he conceded, was finding enough riders who did wear helmets voluntarily to show it made a difference.
Ratner approached Josh Hartnett, Jude Law, Paul Walker and Brendan Fraser for Superman, but conceded that finding a famous actor for the title role had proven difficult because of contractual obligations to appear in sequels.
Privately, however, some former executives concede that finding new suppliers is time-consuming and costly.
Investment banks in Hong Kong privately concede that finding a "princeling" who is valuable for reasons other than their connections is the exception, not the rule.
Indeed, both Silver and Hassabis concede that finding ways for machines to learn from much less data will be important in their ongoing quest to master intelligence.
One study, the Voice Against Women Survey in 2006, conceded its findings were out of step with others, but concluded that intimate partner violence "varied little according to education, labour force status or household income".
There is also speculation over the role of Brailsford, as the performance director concedes he is finding it "more and more difficult" to reconcile his twin roles of heading the Olympic programme and the Team Sky professional squad.
Even Oberweis concedes, however, that finding small-cap growth companies trading at reasonable multiples has become a challenge.
