Permanent constant shocks

permanent_constant is zero before its start year and uses one value from the start year through the model horizon.

Start in the layer event year

layers:
  - id: inflation_target
    name: Inflation-target increase
    data_file_name: inflation_target.csv
    event_year: 2026
    description: Permanent increase in the USA inflation target
    shocks:
      - variable_prefix: INFX
        selectors:
          - dimension: regions
            members: [USA]
        value_path:
          type: permanent_constant
          value: 1.0
          units: percentage points

With no start_year, the layer event year is used.

Year	2026	2027	2028	2029
Value	1.0	1.0	1.0	1.0

Start after the event year

value_path:
  type: permanent_constant
  start_year: 2028
  value: 0.5
  units: percentage points

Year	2026	2027	2028	2029
Value	0	0	0.5	0.5

Apply a reduction to a member group

member_groups:
  selected_regions:
    members: [USA, CHN]
layers:
  - id: policy_reduction
    name: Policy reduction
    data_file_name: policy_reduction.csv
    event_year: 2026
    description: Permanent reduction for selected regions
    shocks:
      - variable_prefix: INFX
        selectors:
          - dimension: regions
            member_group: selected_regions
        value_path:
          type: permanent_constant
          value: -0.25
          units: percentage points

Year	2026	2027	2028	2029
Value for each selected region	-0.25	-0.25	-0.25	-0.25

An omitted value or a start_year before the layer event year is invalid.

Temporary constant shocks