CPI Tracker Oracle
Description
The oracle uses Chainlink's December 2021 CPI-U data point (provided by Fiews) as the 'base' index for determining the peg price. Each month, the change / delta percent of the index is applied to the previous month's data point to determine the peg price. December 2021 was chosen because the oracle contract requires two initial 'historical' data points.
Example:
December 2021 CPI-U: 280.126
January 2022 CPI-U: 281.933
Delta is (281.933 / 280.126) - 1 = 0.64506686%
Assuming December 2021 is $1, applying the delta percentage gives
$1 x (1.0064506686) = $1.0064506686 as the peg price.
If February 2022 CPI-U data was 284.182, the delta would be (284.182 / 281.933) - 1 = 0.79770726%.
Applying this to the previous peg price would give $1.0064506686 * (1 + 0.0079770726) = $1.0144791987 as the new peg price. In other words, you would need this many Feb 2022 dollars to buy one Dec 2021 dollar.
CPITrackerOracle (V2): 0x66B7DFF2Ac66dc4d6FBB3Db1CB627BBb01fF3146
Raw data source: https://data.bls.gov/timeseries/CUSR0000SA0
Chainlink / Fiews Oracle: https://etherscan.io/address/0x049Bd8C3adC3fE7d3Fc2a44541d955A537c2A484
https://market.link/jobs/44964ac4-d302-4141-8f94-67e58e34b88d
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