Table 2 Some of the Principal Models in the Structural Framework,,,,
Type of model,? 2?,? 2?,? 2?,? 2?
Level only,,,,
Constant mean,yes,0,0,0
Local level,yes,yes,0,0
Random walk,0,yes,0,0
Trend only,,,,
Deterministic,yes,0,0,0
Local level with fixed slope,yes,yes,0,0
Random walk with fixed drift,0,yes,0,0
Local linear trend (Holt),yes,yes,yes,0
Smooth trend,yes,0,yes,0
Second difference,0,0,yes,0
Seasonal (with selected trend),,,,
Fixed seasonals,(yes or 0),(yes or 0),(yes or 0),0
Varying seasonals,(yes or 0),(yes or 0),(yes or 0),yes
Basic Structural Model,yes,yes,yes,yes
"Source: Based on Koopman et al. (2000), p. 141.",,,,