# estimate

Fit univariate regression model with ARIMA errors to data

## Syntax

## Description

returns the fully specified regression model with ARIMA errors
`EstMdl`

= estimate(`Mdl`

,`y`

)`EstMdl`

. This model stores the estimated parameter values resulting
from fitting the partially specified, univariate regression model with ARIMA errors
`Mdl`

to the observed univariate time series `y`

by
using maximum likelihood. `EstMdl`

and `Mdl`

are the
same model type and have the same structure.

This syntax specifies an intercept-only regression model.

`[`

also returns the estimated variance-covariance matrix associated with estimated parameters `EstMdl`

,`EstParamCov`

,`logL`

,`info`

] = estimate(___)`EstParamCov`

, the optimized loglikelihood objective function `logL`

, and a data structure of summary information `info`

.

fits the partially specified regression model with ARIMA errors `EstMdl`

= estimate(`Mdl`

,`Tbl1`

)`Mdl`

to
response variable and optional predictor data in the input table or timetable
`Tbl1`

, which contains time series data, and returns the fully
specified, estimated regression model with ARIMA errors `EstMdl`

.
`estimate`

selects the response variable named in
`Mdl.SeriesName`

or the sole variable in `Tbl1`

. To
select a different response variable in `Tbl1`

to fit the model to, use
the `ResponseVariable`

name-value argument. To select predictor
variables for the model regression component, use the
`PredictorVariables`

name-value argument. * (since R2023b)*

`[___] = estimate(___,`

specifies options using one or more name-value arguments in
addition to any of the input argument combinations in previous syntaxes.
`Name,Value`

)`estimate`

returns the output argument combination for the
corresponding input arguments. For example, `estimate(Mdl,y,U0=u0,X=Pred)`

fits the
regression model with ARIMA errors `Mdl`

to the vector of response data
`y`

, specifies the vector of presample regression residual data
`u0`

, and includes a linear regression term in the model for the
predictor data `Pred`

.

Supply all input data using the same data type. Specifically:

If you specify the numeric vector

`y`

, optional data sets must be numeric arrays and you must use the appropriate name-value argument. For example, to specify a presample, set the`Y0`

name-value argument to a numeric matrix of presample data.If you specify the table or timetable

`Tbl1`

, optional data sets must be tables or timetables, respectively, and you must use the appropriate name-value argument. For example, to specify a presample, set the`Presample`

name-value argument to a table or timetable of presample data.

## Examples

### Compare Model Fits By Using Likelihood Ratio Test

Fit this regression model with ARMA(2,1) errors to simulated data:

$$\begin{array}{l}\begin{array}{c}{y}_{t}=1+{X}_{t}\left[\begin{array}{c}0.1\\ -0.2\end{array}\right]+{u}_{t}\\ {u}_{t}=0.5{u}_{t-1}-0.8{u}_{t-2}+{\epsilon}_{t}-0.5{\epsilon}_{t-1},\end{array}\end{array}$$

where $${\epsilon}_{t}$$ is Gaussian with variance 0.1. Compare the fit to an intercept-only regression model by conducting a likelihood ratio test. Provide response and predictor data in vectors.

**Simulate Data**

Specify the regression model with ARMA(2,1) errors. Simulate responses from the model, and simulate two predictor series from the standard Gaussian distribution.

Mdl0 = regARIMA(Intercept=1,AR={0.5 -0.8},MA=-0.5, ... Beta=[0.1; -0.2],Variance=0.1); rng(1,"twister") % For reproducibility Pred = randn(100,2); y = simulate(Mdl0,100,X=Pred);

`y`

is a 100-by-1 random response path simulated from `Mdl0`

.

**Fit Unrestricted Model**

Create an unrestricted model template of a regression model with ARMA(2,1) errors for estimation.

Mdl = regARIMA(2,0,1)

Mdl = regARIMA with properties: Description: "ARMA(2,1) Error Model (Gaussian Distribution)" SeriesName: "Y" Distribution: Name = "Gaussian" Intercept: NaN Beta: [1×0] P: 2 Q: 1 AR: {NaN NaN} at lags [1 2] SAR: {} MA: {NaN} at lag [1] SMA: {} Variance: NaN

The AR coefficients, MA coefficients, and the innovation variance are `NaN`

values. `estimate`

estimates those parameters. When `Beta`

is an empty array, `estimate`

determines the number of regression coefficients to estimate.

Fit the unrestricted model to the data. Specify the predictor data. Return the optimized loglikelihood.

[EstMdlUR,~,logLUR] = estimate(Mdl,y,X=Pred);

Regression with ARMA(2,1) Error Model (Gaussian Distribution): Value StandardError TStatistic PValue ________ _____________ __________ __________ Intercept 1.0167 0.010154 100.13 0 AR{1} 0.64995 0.093794 6.9295 4.2226e-12 AR{2} -0.69174 0.082575 -8.3771 5.4247e-17 MA{1} -0.64508 0.11055 -5.835 5.3796e-09 Beta(1) 0.10866 0.020965 5.183 2.1835e-07 Beta(2) -0.20979 0.022824 -9.1917 3.8679e-20 Variance 0.073117 0.008716 8.3888 4.9121e-17

`EstMdlUR`

is a fully specified `regARIMA`

object representing the estimated unrestricted regression model with ARIMA errors.

**Fit Restricted Model**

The restricted model contains the same error model, but the regression model contains only an intercept. That is, the restricted model imposes two restrictions on the unrestricted model: ${\beta}_{1}={\beta}_{2}=0$.

Fit the restricted model to the data. Return the optimized loglikelihood.

[EstMdlR,~,logLR] = estimate(Mdl,y);

ARMA(2,1) Error Model (Gaussian Distribution): Value StandardError TStatistic PValue ________ _____________ __________ __________ Intercept 1.0176 0.024905 40.859 0 AR{1} 0.51541 0.18536 2.7805 0.0054271 AR{2} -0.53359 0.10949 -4.8735 1.0963e-06 MA{1} -0.34923 0.19423 -1.798 0.07218 Variance 0.1445 0.020214 7.1486 8.7671e-13

`EstMdlR`

is a fully specified `regARIMA`

object representing the estimated restricted regression model with ARIMA errors.

**Conduct Likelihood Ratio Test**

The likelihood ratio test requires the optimized loglikelihoods of the unrestricted and restricted models, and it requires the number of model restrictions (degrees of freedom).

Conduct a likelihood ratio test to determine which model has the better fit to the data.

dof = 2; [h,p] = lratiotest(logLUR,logLR,dof)

`h = `*logical*
1

p = 1.6653e-15

The $\mathit{p}$-value is close to zero, which suggests that there is strong evidence to reject the null hypothesis that the data fits the restricted model better than the unrestricted model.

### Fit Regression Model With ARIMA Errors to Response and Predictor Variables in Timetable

*Since R2023b*

Fit a regression model with ARMA(1,1) errors by regressing the US consumer price index (CPI) quarterly changes onto the US gross domestic product (GDP) growth rate. Supply a timetable of data and specify the series for the fit.

**Load and Transform Data**

Load the US macroeconomic data set. Compute the series of GDP quarterly growth rates and CPI quarterly changes.

load Data_USEconModel DTT = price2ret(DataTimeTable,DataVariables="GDP"); DTT.GDPRate = 100*DTT.GDP; DTT.CPIDel = diff(DataTimeTable.CPIAUCSL); T = height(DTT)

T = 248

figure tiledlayout(2,1) nexttile plot(DTT.Time,DTT.GDPRate) title("GDP Rate") ylabel("Percent Growth") nexttile plot(DTT.Time,DTT.CPIDel) title("Index")

The series appear stationary, albeit heteroscedastic.

**Prepare Timetable for Estimation**

When you plan to supply a timetable, you must ensure it has all the following characteristics:

The selected response variable is numeric and does not contain any missing values.

The timestamps in the

`Time`

variable are regular, and they are ascending or descending.

Remove all missing values from the timetable.

DTT = rmmissing(DTT); T_DTT = height(DTT)

T_DTT = 248

Because each sample time has an observation for all variables, `rmmissing`

does not remove any observations.

Determine whether the sampling timestamps have a regular frequency and are sorted.

`areTimestampsRegular = isregular(DTT,"quarters")`

`areTimestampsRegular = `*logical*
0

areTimestampsSorted = issorted(DTT.Time)

`areTimestampsSorted = `*logical*
1

`areTimestampsRegular = 0`

indicates that the timestamps of `DTT`

are irregular. `areTimestampsSorted = 1`

indicates that the timestamps are sorted. Macroeconomic series in this example are timestamped at the end of the month. This quality induces an irregularly measured series.

Remedy the time irregularity by shifting all dates to the first day of the quarter.

dt = DTT.Time; dt = dateshift(dt,"start","quarter"); DTT.Time = dt; areTimestampsRegular = isregular(DTT,"quarters")

`areTimestampsRegular = `*logical*
1

`DTT`

is regular.

**Create Model Template for Estimation**

Suppose that a regression model of CPI quarterly changes onto the GDP rate, with ARMA(1,1) errors, is appropriate.

Create a model template for a regression model with ARMA(1,1) errors template.

Mdl = regARIMA(1,0,1)

Mdl = regARIMA with properties: Description: "ARMA(1,1) Error Model (Gaussian Distribution)" SeriesName: "Y" Distribution: Name = "Gaussian" Intercept: NaN Beta: [1×0] P: 1 Q: 1 AR: {NaN} at lag [1] SAR: {} MA: {NaN} at lag [1] SMA: {} Variance: NaN

`Mdl`

is a partially specified `regARIMA`

object.

**Fit Model to Data**

Fit a regression model with ARMA(1,1) errors to the data. Specify the entire series GDP rate and CPI quarterly changes series, and specify the response and predictor variable names.

EstMdl = estimate(Mdl,DTT,ResponseVariable="GDPRate", ... PredictorVariables="CPIDel");

Regression with ARMA(1,1) Error Model (Gaussian Distribution): Value StandardError TStatistic PValue ________ _____________ __________ __________ Intercept 0.0162 0.0016077 10.077 6.9995e-24 AR{1} 0.60515 0.089912 6.7305 1.6906e-11 MA{1} -0.16221 0.11051 -1.4678 0.14216 Beta(1) 0.002221 0.00077691 2.8587 0.0042532 Variance 0.000113 7.2753e-06 15.533 2.0838e-54

`EstMdl`

is a fully specified, estimated `regARIMA`

object. By default, `estimate`

backcasts for the required `Mdl.P = 1`

presample regression model residual and sets the required `Mdl.Q = 1`

presample error model residual to 0.

### Initialize Model By Providing Pilot Sample Estimates

*Since R2023b*

Fit a regression model with ARMA(1,1) errors by regressing the US CPI quarterly changes onto the US GDP growth rate. Obtain initial parameter values by fitting a pilot sample.

Load the US macroeconomic data set. Compute the series of GDP quarterly growth rates and CPI quarterly changes.

load Data_USEconModel DTT = price2ret(DataTimeTable,DataVariables="GDP"); DTT.GDPRate = 100*DTT.GDP; DTT.CPIDel = diff(DataTimeTable.CPIAUCSL); T = height(DTT); % Effective sample size

Remedy the time irregularity by shifting all dates to the first day of the quarter.

dt = DTT.Time; dt = dateshift(dt,"start","quarter"); DTT.Time = dt;

Suppose that a regression model of CPI quarterly changes onto the GDP rate, with ARMA(1,1) errors, is appropriate.

Create a model template for a regression model with ARMA(1,1) errors template. Specify the response series name as `GDPRate`

.

```
Mdl = regARIMA(1,0,1);
Mdl.SeriesName = "GDPRate";
```

Fit the model to a pilot sample of approximately the first 25% of the data. Defer to default initial parameter values.

```
cutoff = floor(0.25*T);
DTT0 = DTT(1:cutoff,:);
DTT1 = DTT((cutoff+1):end,:);
EstMdl0 = estimate(Mdl,DTT0,PredictorVariables="CPIDel");
```

Regression with ARMA(1,1) Error Model (Gaussian Distribution): Value StandardError TStatistic PValue __________ _____________ __________ __________ Intercept 0.012032 0.0041096 2.9279 0.0034126 AR{1} 0.35741 0.31565 1.1323 0.25751 MA{1} 0.059366 0.32435 0.18303 0.85477 Beta(1) 0.029888 0.011311 2.6423 0.0082335 Variance 0.00020617 3.9244e-05 5.2535 1.4921e-07

`EstMdl0`

is a regression model with ARMA(1,1) errors fit to the pilot sample. It contains parameter estimates, with which to initialize the model to fit to the remaining 75% of the data set.

Fit the model to the remaining data. Initialize the optimization algorithm by specifying the parameter estimates obtained from fitting the model to the pilot sample. Also, provide presample regression and error model residuals from the pilot sample fit.

intercept0 = EstMdl0.Intercept; ar0 = EstMdl0.AR{1}; ma0 = EstMdl0.MA{1}; variance0 = EstMdl0.Variance; beta0 = EstMdl0.Beta; PresampleTbl = infer(EstMdl0,DTT0,ResponseVariable="GDPRate", ... PredictorVariables="CPIDel"); % Presample residuals EstMdl1 = estimate(Mdl,DTT1,PredictorVariables="CPIDel",Presample=PresampleTbl, ... PresampleInnovationVariable="GDPRate_ErrorResidual", ... PresampleRegressionDisturbanceVariable="GDPRate_RegressionResidual", ... Intercept0=intercept0,AR0=ar0,MA0=ma0,Variance0=variance0,Beta0=beta0);

Regression with ARMA(1,1) Error Model (Gaussian Distribution): Value StandardError TStatistic PValue __________ _____________ __________ _________ Intercept 0.015837 0.0044514 3.5578 0.000374 AR{1} 0.97895 0.022658 43.205 0 MA{1} -0.83051 0.049504 -16.777 3.616e-63 Beta(1) 0.0023693 0.00077788 3.0458 0.0023204 Variance 7.6585e-05 5.6687e-06 13.51 1.362e-41

## Input Arguments

`Mdl`

— Partially specified regression model with ARIMA errors

`regARIMA`

model object

Partially specified regression model with ARIMA errors, used to indicate constrained
and estimable model parameters, specified as an `regARIMA`

model object returned by `regARIMA`

. Properties
of `Mdl`

describe the model structure and can specify parameter
values.

`estimate`

fits unspecified (`NaN`

-valued)
parameters to the data `y`

.

`estimate`

treats specified parameters as equality constraints
during estimation.

`y`

— Single path of observed response data *y*_{t}

numeric column vector

_{t}

Single path of observed response data *y _{t}*,
to which the model

`Mdl`

is fit, specified as a
`numobs`

-by-1 numeric column vector. The last observation of
`y`

is the latest observation.**Data Types: **`double`

`Tbl1`

— Time series data

table | timetable

*Since R2023b*

Time series data, to which `estimate`

fits the model,
specified as a table or timetable with `numvars`

variables and
`numobs`

rows.

The selected response variable is a numeric vector representing a single path of
`numobs`

observations. You can optionally select a response variable
*y _{t}* from

`Tbl1`

by using
the `ResponseVariables`

name-value argument, and you can select
`numpreds`

predictor variables
*x*for the linear regression component by using the

_{t}`PredictorVariables`

name-value argument.Each row is an observation, and measurements in each row occur simultaneously.
Variables in `Tbl1`

represent the continuation of corresponding
variables in `Presample`

.

If `Tbl1`

is a timetable, it must represent a sample with a
regular datetime time step (see `isregular`

), and the datetime vector `Tbl1.Time`

must be
strictly ascending or descending.

If `Tbl1`

is a table, the last row contains the latest
observation.

### Name-Value Arguments

Specify optional pairs of arguments as
`Name1=Value1,...,NameN=ValueN`

, where `Name`

is
the argument name and `Value`

is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.

*
Before R2021a, use commas to separate each name and value, and enclose*
`Name`

*in quotes.*

**Example: **`esimtate(Mdl,y,U0=u0,X=Pred)`

uses the vector
`u0`

as presample regression residual data to initialize the error model
for estimation, and includes a linear regression component for the predictor data in the
vector `Pred`

.

**Estimation Options**

`ResponseVariable`

— Response variable *y*_{t} to select from `Tbl1`

string scalar | character vector | integer | logical vector

_{t}

*Since R2023b*

Response variable *y _{t}* to select from

`Tbl1`

containing the response data, specified as one of the
following data types:String scalar or character vector containing a variable name in

`Tbl1.Properties.VariableNames`

Variable index (integer) to select from

`Tbl1.Properties.VariableNames`

A length

`numvars`

logical vector, where`ResponseVariable(`

selects variable) = true`j`

from`j`

`Tbl1.Properties.VariableNames`

, and`sum(ResponseVariable)`

is`1`

The selected variable must be a numeric vector and cannot contain missing values
(`NaN`

).

If `Tbl1`

has one variable, the default specifies that variable.
Otherwise, the default matches the variable to name in
`Mdl.SeriesName`

.

**Example: **`ResponseVariable="StockRate2"`

**Example: **`ResponseVariable=[false false true false]`

or
`ResponseVariable=3`

selects the third table variable as the
response variable.

**Data Types: **`double`

| `logical`

| `char`

| `cell`

| `string`

`X`

— Predictor data

numeric matrix

Predictor data for the linear regression component, specified as a numeric matrix
containing `numpreds`

columns. Use `X`

only when you
supply a vector of response data `y`

.

`numpreds`

is the number of predictor variables.

Rows correspond to observations, and the last row contains the latest observation.
`estimate`

does not use the regression component in the
presample period. `X`

must have at least `numobs`

observations. If you supply more rows than necessary, `estimate`

uses the latest observations only. `estimate`

synchronizes
`X`

and `y`

so that the latest observations
(last rows) occur simultaneously.

Columns correspond to individual predictor variables.

By default, `estimate`

excludes the regression component,
regardless of its presence in `Mdl`

.

**Data Types: **`double`

`PredictorVariables`

— Predictor variables *x*_{t} to select from `Tbl1`

string vector | cell vector of character vectors | vector of integers | logical vector

_{t}

*Since R2023b*

Predictor variables *x _{t}* to select from

`Tbl1`

containing predictor data for the regression component,
specified as one of the following data types:String vector or cell vector of character vectors containing

`numpreds`

variable names in`Tbl1.Properties.VariableNames`

A length

`numpreds`

vector of unique indices (positive integers) of variables to select from`Tbl1.Properties.VariableNames`

A length

`numvars`

logical vector, where`PredictorVariables(`

selects variable) = true`j`

from`j`

`Tbl1.Properties.VariableNames`

The selected variables must be numeric vectors and cannot contain missing values
(`NaN`

).

By default, `estimate`

excludes the regression component,
regardless of its presence in `Mdl`

.

**Example: **```
PredictorVariables=["M1SL" "TB3MS"
"UNRATE"]
```

**Example: **`PredictorVariables=[true false true false]`

or
`PredictorVariable=[1 3]`

selects the first and third table
variables to supply the predictor data.

**Data Types: **`double`

| `logical`

| `char`

| `cell`

| `string`

`Options`

— Optimization options

`optimoptions`

optimization controller

Optimization options, specified as an `optimoptions`

optimization
controller. For details on modifying the default values of the optimizer, see `optimoptions`

or `fmincon`

in Optimization Toolbox™.

For example, to change the constraint tolerance to `1e-6`

, set
```
options =
optimoptions(@fmincon,ConstraintTolerance=1e-6,Algorithm="sqp")
```

. Then,
pass `Options`

into `estimate`

using
`Options=options`

.

By default, `estimate`

uses the same default options as
`fmincon`

, except `Algorithm`

is
`"sqp"`

and `ConstraintTolerance`

is
`1e-7`

.

`Display`

— Command Window display option

`"params"`

(default) | `"diagnostics"`

| `"full'"`

| `"iter"`

| `"off"`

| string vector | cell vector of character vectors

Command Window display option, specified as one or more of the values in this table.

Value | Information Displayed |
---|---|

`"diagnostics"` | Optimization diagnostics |

`"full"` | Maximum likelihood parameter estimates, standard errors, t statistics, iterative optimization information, and optimization diagnostics |

`"iter"` | Iterative optimization information |

`"off"` | None |

`"params"` | Maximum likelihood parameter estimates, standard errors, and
t statistics and p-values
of coefficient significance tests |

**Example: **`Display="off"`

is well suited for running a simulation that
estimates many models.

**Example: **`Display=["params" "diagnostics"]`

displays all estimation
results and the optimization diagnostics.

**Data Types: **`char`

| `cell`

| `string`

**Presample Specifications**

`E0`

— Presample error model residual data associated with model innovations *ε*_{t}

numeric column vector

Presample error model residual data associated with the model innovations
*ε*_{t}, specified as a
`numpreobs`

-by-1 numeric column vector. `E0`

initializes the error model moving average (MA) component.
`estimate`

assumes `E0`

has a mean of 0. Use
`E0`

only when you supply the vector of response data
`y`

.

`numpreobs`

is the number of presample observations. Each row is
a presample observation. The last row contains the latest presample observation.
`numpreobs`

must be at least `Mdl.Q`

. If
`numpreobs`

> `Mdl.Q`

,
`estimate`

uses the latest required number of observations
only. The last element or row contains the latest observation.

By default, `estimate`

sets all required presample error
model residuals to `0`

, which is the expected value of the
corresponding innovations series.

**Data Types: **`double`

`U0`

— Presample regression residual data associated with unconditional disturbances *u*_{t}

numeric column vector

Presample regression residual data associated with the unconditional disturbances
*u*_{t}, specified as a
`numpreobs`

-by-1 numeric column vector. `U0`

initializes the error model autoregressive (AR) component. Use `U0`

only when you supply the vector of response data `y`

.

`numpreobs`

is the number of presample observations. Each row is
a presample observation. The last row contains the latest presample observation.
`numpreobs`

must be at least `Mdl.P`

. If
`numpreobs`

> `Mdl.P`

,
`estimate`

uses the latest required number of observations
only. The last element or row contains the latest observation.

By default, `estimate`

backcasts the error model for the
required presample unconditional disturbances.

**Data Types: **`double`

`Presample`

— Presample data

table | timetable

*Since R2023b*

Presample data containing the error model residual series, associated with the
model innovations *ε*_{t}, or
the regression residual series, associated with the unconditional disturbances
*u*_{t}, to initialize the
model for estimation, specified as a table or timetable, the same type as
`Tbl1`

, with `numprevars`

variables and
`numpreobs`

rows. Use `Presample`

only when you
supply a table or timetable of data `Tbl1`

.

Each selected variable is a single path of `numpreobs`

observations representing the presample of error or regression model residuals
associated the selected response variable in `Tbl1`

.

Each row is a presample observation, and measurements in each row occur
simultaneously. `numpreobs`

must satisfy one of the following conditions:

`numpreobs`

≥`Mdl.P`

when`Presample`

provides only presample regression model residuals`numpreobs`

≥`Mdl.Q`

when`Presample`

provides only presample error model residuals`numpreobs`

≥`max([Mdl.P Mdl.Q])`

when`Presample`

provides presample error and regression model residuals.

If you supply more rows than necessary,
`estimate`

uses the latest required number of observations
only.

If `Presample`

is a timetable, all the following conditions
must be true:

`Presample`

must represent a sample with a regular datetime time step (see`isregular`

).The inputs

`Tbl1`

and`Presample`

must be consistent in time such that`Presample`

immediately precedes`Tbl1`

with respect to the sampling frequency and order.The datetime vector of sample timestamps

`Presample.Time`

must be ascending or descending.

If `Presample`

is a table, the last row contains the latest
presample observation.

By default, `estimate`

backcasts for necessary presample
regression model residuals and it sets necessary presample error model residuals to
zero.

If you specify `Presample`

, you must specify at least one of
the presample regression or error model residual variable names by using the
`PresampleRegressionDisturbanceVariable`

or
`PresampleInnovationVariable`

name-value argument,
respectively.

`PresampleInnovationVariable`

— Error model residual variable to select from `Presample`

string scalar | character vector | integer | logical vector

*Since R2023b*

Error model residual variable to select from `Presample`

containing presample error model residual data, associated with the model innovations
*ε*_{t}, specified as one of
the following data types:

String scalar or character vector containing the variable name to select from

`Presample.Properties.VariableNames`

Variable index (positive integer) to select from

`Presample.Properties.VariableNames`

A logical vector, where

`PresampleInnovationVariable(`

selects variable) = true`j`

from`j`

`Presample.Properties.VariableNames`

The selected variable must be a numeric vector and cannot contain missing values
(`NaN`

s).

If you specify presample error model residual data by using the
`Presample`

name-value argument, you must specify
`PresampleInnovationVariable`

.

**Example: **`PresampleInnovationVariable="GDPInnov"`

**Example: **`PresampleInnovationVariable=[false false true false]`

or
`PresampleInnovationVariable=3`

selects the third table variable
for presample error model residual data.

**Data Types: **`double`

| `logical`

| `char`

| `cell`

| `string`

`PresampleRegressionDistrubanceVariable`

— Regression model residual variable to select from `Presample`

string scalar | character vector | integer | logical vector

*Since R2023b*

Regression model residual variable to select from `Presample`

containing presample data for the regression model residuals, associated with the
unconditional disturbances *u _{t}*, specified as
one of the following data types:

String scalar or character vector containing a variable name in

`Presample.Properties.VariableNames`

Variable index (positive integer) to select from

`Presample.Properties.VariableNames`

A logical vector, where

`PresampleRegressionDistrubanceVariable(`

selects variable) = true`j`

from`j`

`Presample.Properties.VariableNames`

The selected variable must be a numeric vector and cannot contain missing values
(`NaN`

s).

If you specify presample regression residual data by using the
`Presample`

name-value argument, you must specify
`PresampleRegressionDistrubanceVariable`

.

**Example: **`PresampleRegressionDistrubanceVariable="StockRateU"`

**Example: **```
PresampleRegressionDistrubanceVariable=[false false true
false]
```

or `PresampleRegressionDistrubanceVariable=3`

selects the third table variable as the presample regression model residual
data.

**Data Types: **`double`

| `logical`

| `char`

| `cell`

| `string`

**Initial Parameter Value Specifications**

`Intercept0`

— Initial estimate of regression model intercept *c*

numeric scalar

Initial estimate of the regression model intercept *c*, specified
as a numeric scalar.

By default, `estimate`

derives initial estimates using standard time series techniques.

**Data Types: **`double`

`AR0`

— Initial estimates of nonseasonal autoregressive (AR) polynomial coefficients *ɑ*(*L*)

numeric vector

Initial estimates of the nonseasonal AR polynomial coefficients
*ɑ*(*L*), specified as a numeric vector.

Elements of `AR0`

correspond to nonzero cells of
`Mdl.AR`

.

By default, `estimate`

derives initial estimates using standard time series techniques.

**Data Types: **`double`

`SAR0`

— Initial estimates of seasonal AR polynomial coefficients *A*(*L*)

numeric vector

Initial estimates of the seasonal AR polynomial coefficients
*A*(*L*), specified as a numeric vector.

Elements of `SAR0`

correspond to nonzero cells of
`Mdl.SAR`

.

By default, `estimate`

derives initial estimates using standard time series techniques.

**Data Types: **`double`

`MA0`

— Initial estimates of nonseasonal moving average (MA) polynomial coefficients *b*(*L*)

numeric vector

Initial estimates of the nonseasonal MA polynomial coefficients
*b*(*L*), specified as a numeric vector.

Elements of `MA0`

correspond to elements of
`Mdl.MA`

.

By default, `estimate`

derives initial estimates using standard time series techniques.

**Data Types: **`double`

`SMA0`

— Initial estimates of seasonal MA polynomial coefficients *B*(*L*)

numeric vector

Initial estimates of the seasonal moving average polynomial coefficients
*B*(*L*), specified as a numeric vector.

Elements of `SMA0`

correspond to nonzero cells of
`Mdl.SMA`

.

By default, `estimate`

derives initial estimates using standard time series techniques.

**Data Types: **`double`

`Beta0`

— Initial estimates of regression coefficients

numeric vector

Initial estimates of the regression coefficients *β*, specified as a numeric vector.

The length of `Beta0`

must equal the `numpreds`

. Elements of `Beta0`

correspond to the predictor variables represented by the columns of `X`

or `PredictorVariables`

.

By default, `estimate`

derives initial estimates using standard time series techniques.

**Data Types: **`double`

`DoF0`

— Initial estimate of *t*-distribution degrees-of-freedom parameter

`10`

(default) | positive scalar

Initial estimate of the *t*-distribution degrees-of-freedom parameter
*ν*, specified as a positive scalar. `DoF0`

must
exceed 2.

**Data Types: **`double`

`Variance0`

— Initial estimates of error model innovation variance *σ*_{t}^{2}

positive scalar

_{t}

Initial estimate of the error model innovation variance
*σ _{t}*

^{2}, specified as a positive scalar.

By default, `estimate`

derives initial estimates using standard time series techniques.

**Example: **`Variance0=2`

**Data Types: **`double`

**Note**

`NaN`

values in`y`

,`X`

,`E0`

, and`U0`

indicate missing values.`estimate`

removes missing values from specified data by listwise deletion.For the presample,

`estimate`

horizontally concatenates`E0`

and`U0`

, and then it removes any row of the concatenated matrix containing at least one`NaN`

.For the estimation sample,

`estimate`

horizontally concatenates`y`

and`X`

, and then it removes any row of the concatenated matrix containing at least one`NaN`

.Regardless of sample,

`estimate`

synchronizes the specified, possibly jagged vectors with respect to the latest observation of the sample (last row).

This type of data reduction reduces the effective sample size and can create an irregular time series.

`estimate`

issues an error when any table or timetable input contains missing values.The intercept

*c*of a regression model with ARIMA errors having nonzero degrees of seasonal or nonseasonal integration,`Mdl.Seasonality`

or`Mdl.D`

, is not identifiable. In other words,`estimate`

cannot estimate an intercept of a regression model with ARIMA errors that has nonzero degrees of seasonal or nonseasonal integration. If you pass in such a model for estimation,`estimate`

displays a warning in the Command Window and sets`EstMdl.Intercept`

to`NaN`

.If you specify the

`Display`

name-value argument, the value takes precedence over the specifications of the optimization options`Diagnostics`

and`Display`

. Otherwise,`estimate`

honors all selections related to the display of optimization information in the optimization options.

## Output Arguments

`EstMdl`

— Estimated regression model with ARIMA errors

`regARIMA`

model object

Estimated regression model with ARIMA errors, returned as a `regARIMA`

model object. `estimate`

uses maximum
likelihood to calculate all parameter estimates not constrained by
`Mdl`

(that is, it estimates all parameters in `Mdl`

that you set to `NaN`

).

`EstMdl`

is a copy of `Mdl`

that has
`NaN`

values replaced with parameter estimates.
`EstMdl`

is fully specified.

`EstParamCov`

— Estimated covariance matrix of maximum likelihood estimates

positive semidefinite numeric matrix

Estimated covariance matrix of maximum likelihood estimates known to the optimizer, returned as a positive semidefinite numeric matrix.

The rows and columns contain the covariances of the parameter estimates. The standard error of each parameter estimate is the square root of the main diagonal entries.

The rows and columns corresponding to any parameters held fixed as equality constraints are zero vectors.

Parameters corresponding to the rows and columns of `EstParamCov`

appear in the following order:

Intercept

Nonzero

`AR`

coefficients at positive lags, from the smallest to largest lagNonzero

`SAR`

coefficients at positive lags, from the smallest to largest lagNonzero

`MA`

coefficients at positive lags, from the smallest to largest lagNonzero

`SMA`

coefficients at positive lags, from the smallest to largest lagRegression coefficients (when you specify exogenous data), ordered by the columns of

`X`

or entries of`PredictorVariables`

Innovations variance

Degrees of freedom (

*t*-innovation distribution only)

`estimate`

uses the outer product of gradients (OPG) method to
perform covariance matrix
estimation.

**Data Types: **`double`

`logL`

— Optimized loglikelihood objective function value

numeric scalar

Optimized loglikelihood objective function value, returned as a numeric scalar.

**Data Types: **`double`

`info`

— Optimization summary

structure array

Optimization summary, returned as a structure array with the fields described in this table.

Field | Description |
---|---|

`exitflag` | Optimization exit flag (see `fmincon` in Optimization Toolbox) |

`options` | Optimization options controller (see `optimoptions` and `fmincon` in Optimization Toolbox) |

`X` | Vector of final parameter estimates |

`X0` | Vector of initial parameter estimates |

For example, you can display the vector of final estimates by entering `info.X`

in the Command Window.

**Data Types: **`struct`

## Tips

## Algorithms

`estimate`

estimates the parameters as follows:

Initialize the model by applying initial data and parameter values.

Infer the unconditional disturbances from the regression model.

Infer the residuals of the ARIMA error model.

Use the distribution of the innovations to build the likelihood function.

Maximize the loglikelihood function with respect to the parameters using

`fmincon`

.

## References

[1] Box, George E. P., Gwilym M. Jenkins, and Gregory C. Reinsel. *Time Series Analysis: Forecasting and Control*. 3rd ed. Englewood Cliffs, NJ: Prentice Hall, 1994.

[2] Davidson, R., and J. G. MacKinnon. *Econometric Theory and Methods*. Oxford, UK: Oxford University Press, 2004.

[3] Enders, Walter. *Applied Econometric Time Series*. Hoboken, NJ: John Wiley & Sons, Inc., 1995.

[4] Hamilton, James D. *Time Series Analysis*. Princeton, NJ: Princeton University Press, 1994.

[5] Pankratz, A.
*Forecasting with Dynamic Regression Models.* John Wiley & Sons,
Inc., 1991.

[6] Tsay, R. S. *Analysis of Financial Time Series*. 2nd ed. Hoboken, NJ: John Wiley & Sons, Inc., 2005.

## Version History

**Introduced in R2013b**

### R2023b: `estimate`

accepts input data in tables and timetables

In addition to accepting input data (in-sample and presample data) in numeric arrays,
`estimate`

accepts input data in tables or regular timetables. When
you supply data in a table or timetable, `estimate`

chooses the
default series on which to operate, but you can use the specified optional name-value
argument to select a different series.

Name-value arguments to support tabular workflows include:

`ResponseVariable`

specifies the variable name of the response series in the input data`Tbl1`

, to which the model is fit.`PredictorVariables`

specifies the names of the predictor series to select from the input data for the model regression component.`Presample`

specifies the input table or timetable of presample response, regression model residual, and error model residual data.`PresampleResponseVariable`

specifies the variable name of the response series to select from`Presample`

.`PresampleInnovationVariable`

specifies the variable name of the error model residual series to select from`Presample`

.`PresampleRegressionDisturbanceVariable`

specifies the name of the regression residual series to select from`Presample`

.

### R2019b: `estimate`

includes the final lag in all estimated univariate time series model polynomials

`estimate`

includes the final polynomial lag as specified in the input model template for estimation. In other words, the specified polynomial degrees of an input model template returned by an object creation function and the corresponding polynomial degrees of the estimated model returned by estimate are equal.

Before R2019b, `estimate`

removed trailing lags estimated below the tolerance of `1e-12`

.

**Update Code**

Polynomial degrees require minimum presample observations for operations downstream of estimation, such as model forecasting and simulation. If a model template in your code does not describe the data generating process well, then the polynomials in the estimated model can have higher degrees than in previous releases. Consequently, you must supply additional presample responses for operations on the estimated model; otherwise, the function issues an error. For more details, see the `Y0`

name-value argument.

## See Also

### Objects

### Functions

### Topics

- Estimate Regression Model with ARIMA Errors
- Intercept Identifiability in Regression Models with ARIMA Errors
- Alternative ARIMA Model Representations
- Maximum Likelihood Estimation for Conditional Mean Models
- Conditional Mean Model Estimation with Equality Constraints
- Presample Data for Conditional Mean Model Estimation
- Initial Values for Conditional Mean Model Estimation
- Optimization Settings for Conditional Mean Model Estimation

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