Data mining is the process of discovering hidden knowledge/patterns in sea of data - knowledge discovery, that is the technical definition, for business, it is about how best to make use of existing data to further business interest, Data mining is one of the means to answer this need. Data mining has a trendy name now, - Business Intelligence.
Methodology wise, you may follow this
CRISP-DM[
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As for free tools, check this out:
the-best-data-minning-tools-you-can-use-for-free-in-your-company[
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You said finding
Quote:
identify the relationships between variables
it should be the area of
Market Basket Analysis[
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