20170727AVU to Staff 27.doc

AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION

JURISDICTION: IDAHO DATE PREPARED: 07/25/2017
CASE NO: AVU-E-17-01/AVU-G-17-01 WITNESS: Tara Knox
REQUESTER: IPUC - Morrison RESPONDER: Tara Knox
TYPE: Production Request DEPARTMENT: State & Federal Regulation
REQUEST NO.: Staff-027 TELEPHONE: [phone]

REQUEST:

Please explain why the Company excluded some months of 2006 from its IC11, IR11, II11, IC21, and II21 regression analyses.

RESPONSE:

The listed sub-groups include autoregressive terms in the final regression. Autoregressive terms are dependent on prior month’s data. IC11 needs data from 3 months back to determine the AR(3) term and therefore the regression calculation uses the adjusted sample starting with April 2006 and 117 data points. IR11, IC21 and II21 needs January 2006 data to determine the February 2006 AR(1) term and therefore the regression calculation uses the adjusted sample of 119 points (beginning February 2006). II11 needs data from 2 months back to determine the AR(2) term and therefore the regression calculation uses the adjusted sample starting with March 2006, 118 data points.