Linear phase-in shocks

linear_phase_in increases evenly from the first active year, reaches the full value in full_year, keeps it through end_year, then returns to zero.

Phase in over three years

layers:
  - id: phased_target
    name: Phased inflation-target adjustment
    data_file_name: phased_target.csv
    event_year: 2026
    description: Phase in a three percentage point adjustment
    shocks:
      - variable_prefix: INFX
        selectors:
          - dimension: regions
            members: [USA]
        value_path:
          type: linear_phase_in
          start_year: 2026
          full_year: 2028
          end_year: 2030
          value: 3.0
          units: percentage points

Year	2026	2027	2028	2029	2030	2031
Value	1.0	2.0	3.0	3.0	3.0	0

The first active year receives the first increment; it is not zero.

Reach the full value immediately

value_path:
  type: linear_phase_in
  start_year: 2027
  full_year: 2027
  end_year: 2029
  value: 2.0
  units: per cent

Year	2026	2027	2028	2029	2030
Value	0	2.0	2.0	2.0	0

Phase in a reduction

value_path:
  type: linear_phase_in
  start_year: 2026
  full_year: 2027
  end_year: 2028
  value: -1.0
  units: percentage points

Year	2026	2027	2028	2029
Value	-0.5	-1.0	-1.0	0

Years must satisfy start_year <= full_year <= end_year and stay within the layer period.

Piecewise-linear shocks