Fix Barber-Candes adjustemt if all p-values are < 0.5

Fixes #81.

Author: juliangehring

src/pval-adjustment.jl

@@ -228,8 +228,12 @@ end
 
 function adjust(pValues::PValues{T}, method::BarberCandes) where T<:AbstractFloat
     n = length(pValues)
+    # special cases unlike other p-adjust methods
     if n <= 1
-        return fill(1.0, size(pValues)) # unlike other p-adjust methods
+        return fill(1.0, size(pValues))
+    end
+    if maximum(pValues) < 0.5
+        return fill(1/n, size(pValues))
     end
 
     sorted_indexes, original_order = reorder(pValues)

test/test-pval-adjustment.jl

@@ -141,6 +141,12 @@ using Base.Test
         end
     end
 
+    @testset "BarberCandès: All p-values < 0.5 (#87)" begin
+        for pv in ([0.05, 0.1, 0.3], [0.01, 0.17, 0.25, 0.37, 0.47])
+            n = length(pv)
+            @test isapprox( adjust(PValues(pv), BarberCandes()), fill(1/n, n) )
+        end
+    end
 
     @testset "Step-up/down" begin