That's one approach. I was suggesting:

$self->{logger}->trace( sub { "total NbObsThis $i=$nbObservedThisNGram
+->[$i]; nbObsAll $i=$nbObservedAllNGrams->[$i]; total=$totalObservedA
+ll; nbExpected $i=$nbExpectedThis[$i]; chisq = $chiSquare[$i]" } );
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which may be easier to bulk modify in source while maintaining existing log levels. (or not. YMMV.)