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sql server data mining : decision tree algorithm parameters..



sqlster
2/28/2006 9:05:28 AM
I have been reading chapter on decision tree algorithm in sql server 2005
data mining book.
Even though it discusses the algorithm parameters very well, is there any
other source where
I could read up on algorithm parameters?

Here is the case I am working on. I have a customer demographic table with
about 8 attributes
and I predict on what (grocery product : fruit, juice, chips, chicken) they
would buy.

Out of 400 cases, I take out 40 cases with known product choice and call it
newpurchase.
Another 100 cases, I separate out for testing as testpurchase and rest it
for training called
trainpurchase.

I played with different attributes in decision tree model and ran it against
newpurchase.
90% of predictions were correct and rest were wrong. I have been looking at
case generated
etc. etc. Is it possible that even though attributes point to the correct
product in
terms of statistics but customer chose a different product any ways????

I could use a real good discussion on decision tree algorithm parameters and
how it influences the growth/pruning of the tree.

Please help and let me know if I need to further clarify this.

sqlster
2/28/2006 9:51:28 AM
Lets say in the training cases, 90 % of the product purchase was chicken and
only 3% was fruit. How can I accurately predict "fruit"? I have been tweaking
the parameters with differernt values and looking into the lift chart. Tried
to make sure
that the split is correct but still no success. Most of the predictions are
"chicken" even though in the newpurchase cases I have 4% fruit.

Please help and TIA...

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ZULFIQAR SYED
3/1/2006 7:47:26 PM
sqlster,
Check out books online for an excellent description on algorithm parameters.

http://msdn2.microsoft.com/en-us/library/ms175312.aspx

HTH..
--
http://zulfiqar.typepad.com
BSEE, MCP


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