arch.univariate.ConstantMean¶

Constant mean model estimation and simulation.

Parameters:¶

y: ndarray | DataFrame | Series | None = None¶: Vector of nobs elements containing the dependent variable.
hold_back: int | None = None¶: Number of observations at the start of the sample to exclude when estimating model parameters. Used when comparing models with different lag lengths to estimate on the common sample. Must be a non-negative integer.
volatility: VolatilityProcess | None = None¶: Volatility process to use in the model.
distribution: Distribution | None = None¶: Error distribution to use in the model.
rescale: bool | None = None¶: Flag indicating whether to automatically rescale data if the scale of the data is likely to produce convergence issues when estimating model parameters. If False, the model is estimated on the data without transformation. If True, then y is rescaled and the new scale is reported in the estimation results. If None, the data is not rescaled and a warning is issued when its scale is likely to produce convergence issues.

Raises:¶

TypeError – If hold_back is not an integer (a float, including 5.0, and a bool are not accepted), if rescale is not a bool or None, or if volatility or distribution is not an instance of VolatilityProcess or Distribution.
ValueError – If hold_back is negative.

Notes

The constant mean model is described by

\[y_t = \mu + \epsilon_t\]

Examples

>>> import numpy as np
>>> from arch.univariate import ConstantMean
>>> y = np.random.randn(100)
>>> cm = ConstantMean(y)
>>> res = cm.fit()

Methods

`append`(y[, x])	Append observations to the model in-place.
`bounds`()	Construct bounds for parameters to use in non-linear optimization.
`compute_param_cov`(params[, backcast, robust])	Compute parameter covariances using numerical derivatives.
`constraints`()	Construct linear constraint arrays for use in non-linear optimization.
`fit`([update_freq, disp, starting_values, ...])	Estimate model parameters.
`fix`(params[, first_obs, last_obs])	Construct an ARCHModelFixedResult from fixed parameters.
`forecast`(params[, horizon, start, align, ...])	Construct forecasts from estimated model.
`parameter_names`()	Return the names of the parameters of the mean model.
`resids`(params[, y, regressors])	Compute model residuals.
`simulate`(params, nobs[, burn, ...])	Simulate data from a constant mean model.
`starting_values`()	Return starting values for the mean model.

Properties

`distribution`	Get or set the error distribution.
`name`	The name of the model.
`num_params`	Number of parameters in the model.
`volatility`	Get or set the volatility process.
`x`	The exogenous regressors in the model.
`y`	The dependent variable.