














• 
There is no need
to fit a model to the data.




– 
We
just compute some very simple statistics (the



number
of datapoints in each bin) and store them.



• 
The number of
bins is exponential in the dimensionality



of the
dataspace. So highdimensional data is tricky:




– 
We
must either use big bins or get lots of zero counts


(or
adapt the local binwidth to the density)



• 
The density has
silly discontinuities at the bin



boundaries.




– 
We
must be able to do better by some kind of



smoothing.

