Gio Wiederhold PDM 7
3. Establish causality
•Already known -- Prior Model
–But is it complete,
i.e., does it explain all effects ?
•Analyze relationships
– use expertise to decide
direction
»often obvious
"common world knowledge"
»sometimes ambiguous
smoking
Ø
Cancer Ø not-smoking
»often major true cause not captured in
data
food color 10%,
food
price 20%,
buyer
gender 2%
unknown 75%
guess: ethnicity, income
purchase of
Chinese vs other food
invent
surrogates: names, ZIP codes,
use temporal
information