Model initialization — model_initialization • markets

Model initialization

Usage

# S4 method for diseq_basic
initialize(
  .Object,
  quantity,
  price,
  demand,
  supply,
  subject,
  time,
  data,
  correlated_shocks = TRUE,
  verbose = 0
)

# S4 method for diseq_deterministic_adjustment
initialize(
  .Object,
  quantity,
  price,
  demand,
  supply,
  subject,
  time,
  data,
  correlated_shocks = TRUE,
  verbose = 0
)

# S4 method for diseq_directional
initialize(
  .Object,
  quantity,
  price,
  demand,
  supply,
  subject,
  time,
  data,
  correlated_shocks = TRUE,
  verbose = 0
)

# S4 method for diseq_stochastic_adjustment
initialize(
  .Object,
  quantity,
  price,
  demand,
  supply,
  price_dynamics,
  subject,
  time,
  data,
  correlated_shocks = TRUE,
  verbose = 0
)

# S4 method for equilibrium_model
initialize(
  .Object,
  quantity,
  price,
  demand,
  supply,
  subject,
  time,
  data,
  correlated_shocks = TRUE,
  verbose = 0
)

Arguments

.Object: The object to be Constructed.
quantity: The quantity variable of the system.
price: The price variable of the system.
demand: A formula representation of the right hand side of the demand equation.
supply: A formula representation of the right hand side of the supply equation.
subject: The subject identifier of the data set.
time: The time identifier of the data set.
data: The data set.
correlated_shocks: Should the model be estimated using correlated shocks?
verbose: Verbosity level.
price_dynamics: A formula representation of the price equation.

Value

The initialized model.

Details

The following two subsections describe the common initialization steps of all market model classes.

Variable construction

The constructor prepares the model's variables using the passed specifications. The specification variables are expected to be of type language. The right hand side specifications of the system are expected to follow the syntax of formula. The construction of the model's data uses the variables extracted by these specification. The demand variables are extracted by a formula that uses the quantity on the left hand side and the demand on the right hand side of the formula. The supply variables are constructed by the quantity and the supply inputs. In the case of the diseq_stochastic_adjustment model, the price dynamics' variables are extracted using the price dynamics input. The price dynamics for the diseq_stochastic_adjustment should contain only terms other than that of excess demand. The excess demand term of the price equation is automatically generated by the constructor.

Data preparation

1. If the passed data set contains rows with NA values, they are dropped. If the verbosity level allows warnings, a warning is emitted reporting how many rows were dropped.

2. After dropping the rows, factor levels may be invalidated. If needed, the constructor readjusts the factor variables by removing the unobserved levels. Factor indicators and interaction terms are automatically created.

3. The primary key column is constructed by pasting the values of the columns of the subject and time variables.

4. In the cases of the diseq_directional, diseq_deterministic_adjustment, and the diseq_stochastic_adjustment models, a column with lagged prices is constructed. Since lagged prices are unavailable for the observations of the first time point, these observations are dropped. If the verbosity level allows the emission of information messages, the constructor prints the number of dropped observations.

5. In the cases of the diseq_directional and the diseq_stochastic_adjustment models, a column with price differences is created.

Functions

initialize(diseq_basic): Basic disequilibrium model base constructor
initialize(diseq_deterministic_adjustment): Disequilibrium model with deterministic price adjustment constructor
initialize(diseq_directional): Directional disequilibrium model base constructor
initialize(diseq_stochastic_adjustment): Disequilibrium model with stochastic price adjustment constructor
initialize(equilibrium_model): Equilibrium model constructor

Examples

simulated_data <- simulate_data(
  "diseq_basic", 500, 3, # model type, observed entities, observed time points
  -0.9, 8.9, c(0.3, -0.2), c(-0.03, -0.01), # demand coefficients
  0.9, 6.2, c(0.03), c(-0.05, 0.02) # supply coefficients
)

# initialize the model
model <- new(
  "diseq_basic", # model type
  subject = id, time = date, quantity = Q, price = P,
  demand = P + Xd1 + Xd2 + X1 + X2, supply = P + Xs1 + X1 + X2,
  simulated_data, # data
  correlated_shocks = FALSE # use independent shocks
)

show(model)
#> Basic Model for Markets in Disequilibrium:
#>   Demand RHS        :   D_P + D_Xd1 + D_Xd2 + D_X1 + D_X2
#>   Supply RHS        :   S_P + S_Xs1 + S_X1 + S_X2
#>   Short Side Rule   : Q = min(D_Q, S_Q)
#>   Shocks            : Independent
simulated_data <- simulate_data(
  # model type, observed entities and time points
  "diseq_deterministic_adjustment", 500, 3,
  # demand coefficients
  -0.9, 8.9, c(0.03, -0.02), c(-0.03, -0.01),
  # supply coefficients
  0.9, 4.2, c(0.03), c(0.05, 0.02),
  # price adjustment coefficient
  1.4
)

# initialize the model
model <- new(
  "diseq_deterministic_adjustment", # model type
  subject = id, time = date, quantity = Q, price = P,
  demand = P + Xd1 + Xd2 + X1 + X2, supply = P + Xs1 + X1 + X2,
  simulated_data, # data
  correlated_shocks = TRUE # allow shocks to be correlated
)

show(model)
#> Deterministic Adjustment Model for Markets in Disequilibrium:
#>   Demand RHS        :   D_P + D_Xd1 + D_Xd2 + D_X1 + D_X2
#>   Supply RHS        :   S_P + S_Xs1 + S_X1 + S_X2
#>   Short Side Rule   : Q = min(D_Q, S_Q)
#>   Separation Rule   : P_DIFF analogous to (D_Q - S_Q)
#>   Shocks            : Correlated
# \donttest{
simulated_data <- simulate_data(
  "diseq_directional", 500, 3, # model type, observed entities, observed time points
  -0.2, 4.3, c(0.03, 0.02), c(0.03, 0.01), # demand coefficients
  0.0, 4.0, c(0.03), c(0.05, 0.02) # supply coefficients
)

# in the directional model prices cannot be included in both demand and supply
model <- new(
  "diseq_directional", # model type
  subject = id, time = date, quantity = Q, price = P,
  demand = P + Xd1 + Xd2 + X1 + X2, supply = Xs1 + X1 + X2,
  simulated_data, # data
  correlated_shocks = TRUE # allow shocks to be correlated
)

show(model)
#> Directional Model for Markets in Disequilibrium:
#>   Demand RHS        :   D_P + D_Xd1 + D_Xd2 + D_X1 + D_X2
#>   Supply RHS        :   S_Xs1 + S_X1 + S_X2
#>   Short Side Rule   : Q = min(D_Q, S_Q)
#>   Separation Rule   : P_DIFF >= 0 then D_Q >= S_Q
#>   Shocks            : Correlated
# }
simulated_data <- simulate_data(
  # model type, observed entities and time points
  "diseq_stochastic_adjustment", 500, 3,
  # demand coefficients
  -0.1, 9.8, c(0.3, -0.2), c(0.6, 0.1),
  # supply coefficients
  0.1, 7.1, c(0.9), c(-0.5, 0.2),
  # price adjustment coefficient
  1.4, 3.1, c(0.8)
)

# initialize the model
model <- new(
  "diseq_stochastic_adjustment", # model type
  subject = id, time = date, quantity = Q, price = P,
  demand = P + Xd1 + Xd2 + X1 + X2, supply = P + Xs1 + X1 + X2,
  price_dynamics = Xp1,
  simulated_data, # data
  correlated_shocks = TRUE # allow shocks to be correlated
)

show(model)
#> Stochastic Adjustment Model for Markets in Disequilibrium:
#>   Demand RHS        :   D_P + D_Xd1 + D_Xd2 + D_X1 + D_X2
#>   Supply RHS        :   S_P + S_Xs1 + S_X1 + S_X2
#>   Price Dynamics RHS:   I(D_Q - S_Q) + Xp1
#>   Short Side Rule   : Q = min(D_Q, S_Q)
#>   Shocks            : Correlated
simulated_data <- simulate_data(
  "equilibrium_model", 500, 3, # model type, observed entities and time points
  -0.9, 14.9, c(0.3, -0.2), c(-0.03, -0.01), # demand coefficients
  0.9, 3.2, c(0.3), c(0.5, 0.02) # supply coefficients
)

# initialize the model
model <- new(
  "equilibrium_model", # model type
  subject = id, time = date, quantity = Q, price = P,
  demand = P + Xd1 + Xd2 + X1 + X2, supply = P + Xs1 + X1 + X2,
  simulated_data, # data
  correlated_shocks = TRUE # allow shocks to be correlated
)

show(model)
#> Equilibrium Model for Markets in Equilibrium:
#>   Demand RHS        :   D_P + D_Xd1 + D_Xd2 + D_X1 + D_X2
#>   Supply RHS        :   S_P + S_Xs1 + S_X1 + S_X2
#>   Market Clearing   : Q = D_Q = S_Q
#>   Shocks            : Correlated