isBest(L, BestTest) :-
        probPosDiseasePosTest1(L, P1Result),
        probPosDiseasePosTest2(L, P2Result),
        probNegDiseaseNegTest1(L, P3Result),
        probNegDiseaseNegTest2(L, P4Result),
        ( P1Result > P2Result , P3Result > P4Result -> BestTest = test1 ; P2Result > P1Result, P4Result > P3Result -> BestTest = test2),
        %( BestTest != 'test1', BestTest != 'test2' -> BestTest is 'neither').