What is SUTVA?

hard

Answer

$Stable Unit Treatment Value Assumption: (1) no interference between units — one unit's treatment doesn't affect another's outcome (breaks in networks, marketplaces, viral products), (2) no hidden treatment variants — one 'treatment' is well-defined.$
$Violated in social networks (spillovers), two-sided marketplaces (Uber: driver-side changes affect rider outcomes), auctions (competition), any system with global equilibrium effects.$
$Fixes: cluster / market-level randomization, switchback experiments.$

Check yourself — multiple choice

Random
No interference + one treatment version; broken in networks, marketplaces, auctions → cluster / market-level randomization or switchback
Same as ignorability
Not needed

SUTVA: no interference + one treatment version; violated in marketplaces / networks.

#causal-inference#ab-testing

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