diff --git a/src/Data/Statistics/Loess.hs b/src/Data/Statistics/Loess.hs
index 96afa10..5700d26 100644
--- a/src/Data/Statistics/Loess.hs
+++ b/src/Data/Statistics/Loess.hs
@@ -6,6 +6,8 @@ import Statistics.Regression (ols)
 import Data.Vector.Unboxed((!), zipWith, length, (++), map)
 import Statistics.Matrix(transpose)
 
+lambda :: Double
+lambda = 1.0
 
 triCube :: Double -> Double
 triCube d = (1.0 - (abs d) ** 3) ** 3
@@ -15,7 +17,7 @@ loess inputs outputs x = a * x + b
   where a = params ! 1
         b = params ! 0
         params = ols inputMatrix scaledOutputs
-        weights = Data.Vector.Unboxed.map (\v -> triCube (x - v)) inputs
+        weights = Data.Vector.Unboxed.map (\v -> lambda * triCube (lambda * (x - v))) inputs
         scaledOutputs = Data.Vector.Unboxed.zipWith (*) outputs weights
         scaledInputs = Data.Vector.Unboxed.zipWith (*) inputs weights
         inputMatrix = transpose (SMT.Matrix 2 (Data.Vector.Unboxed.length inputs) 1000 (weights Data.Vector.Unboxed.++ scaledInputs))