diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,1 +1,16 @@
 # Welford: Online mean and variance computation
+
+
+Example
+
+    example :: [Double] -> IO ()
+    example vals = do
+      let n = fromIntegral (length vals)
+      mean = VB.sum vals / n
+      var = VB.sum (VB.map (\x -> (x - mean) ^ 2) vals) / (n - 1)
+      (wMean, _, wVarSample) = finalize $ foldl' addValue (WelfordExistingAggregateEmpty) (VB.toList vals)
+      print (mean, var)
+      print (wMean, wVarSample)
+
+
+`WelfordExistingAggregate` is used to save the state. Use the function `finalize` to retrieve the current estimates for the mean, variance and sample variance.
diff --git a/src/Statistics/Sample/WelfordOnlineMeanVariance.hs b/src/Statistics/Sample/WelfordOnlineMeanVariance.hs
--- a/src/Statistics/Sample/WelfordOnlineMeanVariance.hs
+++ b/src/Statistics/Sample/WelfordOnlineMeanVariance.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE FlexibleInstances #-}
 module Statistics.Sample.WelfordOnlineMeanVariance
   ( WelfordExistingAggregate(..)
+  , WelfordOnline (..)
   , addValue
   , finalize
   , nextValue
diff --git a/test/Statistics/Sample/WelfordOnlineTest.hs b/test/Statistics/Sample/WelfordOnlineTest.hs
--- a/test/Statistics/Sample/WelfordOnlineTest.hs
+++ b/test/Statistics/Sample/WelfordOnlineTest.hs
@@ -3,7 +3,6 @@
 import           Control.Monad
 import           Data.List                                   (foldl')
 import qualified Data.Vector                                 as VB
-import           Debug.Trace
 import           Test.Tasty.QuickCheck
 
 import           Statistics.Sample.WelfordOnlineMeanVariance
diff --git a/welford-online-mean-variance.cabal b/welford-online-mean-variance.cabal
--- a/welford-online-mean-variance.cabal
+++ b/welford-online-mean-variance.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           welford-online-mean-variance
-version:        0.1.0.0
+version:        0.1.0.1
 synopsis:       Online computation of mean and variance using the Welford algorithm.
 description:    Please see the README on GitHub at <https://github.com/githubuser/welford-online-mean-variance#readme>
 category:       Statistics