20170727AVU to Staff 23.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: Joe Miller
REQUESTER: IPUC - Morrison RESPONDER: Tara Knox
TYPE: Production Request DEPARTMENT: State & Federal Regulation
REQUEST NO.: Staff-023 TELEPHONE: [phone]

REQUEST:

Please explain why the Company excluded January 2006 from its II101, IR111 and IT131 regression analyses.

RESPONSE:

Those three sub-groups include the autoregressive term AR(1) in the final regression. Autoregressive terms are dependent on prior month’s data. January 2006 was necessary to determine the February 2006 AR(1) term and therefore the regression calculation uses the adjusted sample of 119 data points.