We have a process for evaluating how candidates score at each task to be sure their difficulty level fits into the right category. 

Each task we release we analyze further based on how candidates score at it. If we see that, for example, candidates fail too often on a task marked as easy we change its difficulty to medium once we have enough data. 

Right now we're changing the difficulty level of 37 tasks:

AlternatingTrees to medium
AppleOrchard to very-hard
ArrayFilterVarJade to easy
BugfixingKthWord to easy
BugfixingReverseNumber to easy
ConsecutiveDecomposition to easy
DayOfWeek to elementary
DifferentNeighboursLetters to easy
DistributedDistinct to hard
EqualFractions to medium
EraseOneLetter to easy
EvenWord to easy
FairSplits to hard
ForbiddenTrios to elementary
ForbiddenTriosSwaps to easy
IntegerDecimalOccurrence to elementary
JsComments to medium
LessThanThreeDigits to elementary
LongestEvenPath to hard
MaxMagicSquare to easy
OppositeNumbers to easy
PhoneNumberCheck to elementary
Pow11 to easy
SelectedIcon to easy
SemiAlternatingSubstring to easy
ShellAbsSum to easy
ShellFindFunction to medium
SkylinePaint to medium
SmallestSameDigits to elementary
SqlAssignTaskDifficulty to easy
SqlCars to elementary
SqlTheater to easy
SumTo1 to hard
TheWidestPath to easy
TransactionalStack to very-hard
UpsideDown to elementary
ZerolessDecomposition to elementary 

This change affects mostly customers who are going to create new tests.

If you were using one of those tasks, that doesn't necessarily mean you need to change anything - signal you're getting is going to remain the same so in most cases, you don't need to adjust your current tests. 

If you have questions about our task library or need help with your tests, reach out to us at support@codility.com

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