# irf

Generate vector autoregression (VAR) model impulse responses

## Syntax

## Description

The `irf`

function returns the dynamic response, or the impulse response
function (IRF), to a one-standard-deviation shock to each variable in a VAR(*p*)
model. A fully specified `varm`

model object characterizes the VAR
model.

To estimate or plot the IRF of a dynamic linear model characterized by structural,
autoregression, or moving average coefficient matrices, see `armairf`

.

IRFs trace the effects of an innovation shock to one variable on the response of all
variables in the system. In contrast, the forecast error variance decomposition (FEVD)
provides information about the relative importance of each innovation in affecting all
variables in the system. To estimate the FEVD of a VAR model characterized by a
`varm`

model object, see `fevd`

.

You can supply optional data, such as a presample, as a numeric array, table, or
timetable. However, all specified input data must be the same data type. When the input model
is estimated (returned by `estimate`

), supply the same data type as the data
used to estimate the model. The data type of the outputs matches the data type of the
specified input data.

returns a numeric array containing the orthogonalized IRF of the response variables that
compose the VAR(`Response`

= irf(`Mdl`

)*p*) model `Mdl`

, characterized by a
fully specified `varm`

model object.
`irf`

shocks variables at time 0, and returns the IRF for
times 0 through 19.

If `Mdl`

is an estimated model (returned by `estimate`

) fit to a numeric matrix of input response data, this syntax
applies.

returns numeric arrays when all optional input data are numeric arrays. For example,
`Response`

= irf(`Mdl`

,`Name=Value`

)`irf(Mdl,NumObs=10,Method="generalized")`

specifies estimating a
generalized IRF for 10 time points starting at time 0, during which
`irf`

applies the shock.

If `Mdl`

is an estimated model fit to a numeric matrix of input
response data, this syntax applies.

`[`

returns numeric arrays of lower `Response`

,`Lower`

,`Upper`

] = irf(___)`Lower`

and upper
`Upper`

95% confidence bounds for confidence intervals on the true
IRF, for each period and variable in the IRF, using any input argument combination in the
previous syntaxes. By default, `irf`

estimates confidence
bounds by conducting Monte Carlo simulation.

If `Mdl`

is an estimated model fit to a numeric matrix of input
response data, this syntax applies.

If `Mdl`

is a custom `varm`

model object (an object not returned by `estimate`

or modified after estimation), `irf`

can
require a sample size for the simulation `SampleSize`

or presample
responses `Y0`

.

returns the table or
timetable `Tbl`

= irf(___)`Tbl`

containing the IRFs and, optionally, corresponding 95%
confidence bounds, of the response variables that compose the VAR(*p*)
model `Mdl`

. The IRF of the corresponding response is a variable in
`Tbl`

containing a matrix with columns corresponding to the variables
in the system shocked at time 0.* (since R2022b)*

If you set at least one name-value argument that controls the 95% confidence bounds on
the IRF, `Tbl`

also contains a variable for each of the lower and upper
bounds. For example, `Tbl`

contains confidence bounds when you set the
`NumPaths`

name-value argument.

If `Mdl`

is an estimated model fit to a table or timetable of input
response data, this syntax applies.

## Examples

### Specify Data in Numeric Matrix When Plotting IRF

Fit a 4-D VAR(2) model to Danish money and income rate series data in a numeric matrix. Then, estimate and plot the orthogonalized IRF from the estimated model.

Load the Danish money and income data set.

`load Data_JDanish`

For more details on the data set, enter `Description`

at the command line.

Assuming that the series are stationary, create a `varm`

model object that represents a 4-D VAR(2) model. Specify the variable names.

Mdl = varm(4,2); Mdl.SeriesNames = DataTable.Properties.VariableNames;

`Mdl`

is a `varm`

model object specifying the structure of a 4-D VAR(2) model; it is a template for estimation.

Fit the VAR(2) model to the numeric matrix of time series data `Data`

.

Mdl = estimate(Mdl,Data);

`Mdl`

is a fully specified `varm`

model object representing an estimated 4-D VAR(2) model.

Estimate the orthogonalized IRF from the estimated VAR(2) model.

Response = irf(Mdl);

`Response`

is a 20-by-4-by-4 array representing the IRF of `Mdl`

. Rows correspond to consecutive time points from time 0 to 19, columns correspond to variables receiving a one-standard-deviation innovation shock at time 0, and pages correspond to responses of variables to the variable being shocked. `Mdl.SeriesNames`

specifies the variable order.

Display the IRF of the bond rate (variable 3, `IB`

) when the log of real income (variable 2, `Y`

) is shocked at time 0.

Response(:,2,3)

`ans = `*20×1*
0.0018
0.0048
0.0054
0.0051
0.0040
0.0029
0.0019
0.0011
0.0006
0.0003
⋮

Plot the IRFs of all series on separate plots by passing the estimated AR coefficient matrices and innovations covariance matrix of `Mdl`

to `armairf`

.

armairf(Mdl.AR,[],InnovCov=Mdl.Covariance);

Each plot shows the four IRFs of a variable when all other variables are shocked at time 0. `Mdl.SeriesNames`

specifies the variable order.

### Estimate Generalized IRF of VAR Model

Consider the 4-D VAR(2) model in Specify Data in Numeric Matrix When Plotting IRF. Estimate the generalized IRF of the system for 50 periods.

Load the Danish money and income data set, and then estimate the VAR(2) model.

```
load Data_JDanish
Mdl = varm(4,2);
Mdl.SeriesNames = DataTable.Properties.VariableNames;
Mdl = estimate(Mdl,DataTable.Series);
```

Estimate the generalized IRF from the estimated VAR(2) model.

`Response = irf(Mdl,Method="generalized",NumObs=50);`

`Response`

is a 50-by-4-by-4 array representing the generalized IRF of `Mdl`

.

Plot the generalized IRF of the bond rate when real income is shocked at time 0.

figure; plot(0:49,Response(:,2,3)) title("IRF of IB When Y Is Shocked") xlabel("Observation Time") ylabel("Response") grid on

The bond rate fades slowly when real income is shocked at time 0.

### Specify Data in Timetables When Computing IRF and Confidence Intervals

*Since R2022b*

Fit a 4-D VAR(2) model to Danish money and income rate series data in a numeric matrix. Then, estimate and plot the orthogonalized IRF from the estimated model.

Load the Danish money and income data set.

`load Data_JDanish`

The data set includes four time series in the timetable `DataTimeTable`

. For more details on the data set, enter `Description`

at the command line.

Assuming that the series are stationary, create a `varm`

model object that represents a 4-D VAR(2) model. Specify the variable names.

Mdl = varm(4,2); Mdl.SeriesNames = DataTimeTable.Properties.VariableNames;

`Mdl`

is a `varm`

model object specifying the structure of a 4-D VAR(2) model; it is a template for estimation.

Fit the VAR(2) model to the data set.

EstMdl = estimate(Mdl,DataTimeTable);

`Mdl`

is a fully specified `varm`

model object representing an estimated 4-D VAR(2) model.

Estimate the orthogonalized IRF and corresponding 95% confidence intervals from the estimated VAR(2) model. To return confidence intervals, you must set a name-value argument that controls confidence intervals, for example, `Confidence`

. Set `Confidence`

to `0.95`

.

```
rng(1); % For reproducibility
Tbl = irf(EstMdl,Confidence=0.95);
size(Tbl)
```

`ans = `*1×2*
20 12

Tbl

`Tbl=`*20×12 timetable*
Time M2_IRF Y_IRF IB_IRF ID_IRF M2_IRF_LowerBound Y_IRF_LowerBound IB_IRF_LowerBound ID_IRF_LowerBound M2_IRF_UpperBound Y_IRF_UpperBound IB_IRF_UpperBound ID_IRF_UpperBound
___________ _____________________________________________________ _______________________________________________________ ___________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ ______________________________________________________ _______________________________________________________ _____________________________________________________ ___________________________________________________ ____________________________________________________ ___________________________________________________
01-Jul-1974 0.025385 0.011979 -0.0030299 -0.00029592 0 0.017334 0.0017985 -0.00060941 0 0 0.0072384 0.0011766 0 0 0 0.0047648 0.017729 0.0062931 -0.0046236 -0.0012223 0 0.012192 -0.00017736 -0.0016259 0 0 0.0046542 -0.00050518 0 0 0 0.00322 0.02713 0.016442 -0.00074788 0.0010392 0 0.019303 0.0037597 0.00088073 0 0 0.0080468 0.002298 0 0 0 0.0049936
01-Oct-1974 0.019597 0.017604 -0.0024059 -0.00052605 0.0022668 0.014588 0.0047558 0.00037877 -0.011013 -0.0010791 0.0096387 0.0036033 -0.0014511 -0.0044686 -1.6666e-05 0.0043446 0.0088617 0.0075327 -0.0054155 -0.0024484 -0.0045762 0.0055602 0.00085487 -0.0014949 -0.015821 -0.0059937 0.0044639 0.00097209 -0.0072913 -0.0092174 -0.0021639 0.001595 0.024652 0.020779 0.00056005 0.0014407 0.0069932 0.017056 0.0070093 0.0021859 -0.0048396 0.0046483 0.010957 0.0051531 0.0043279 0.00045888 0.0017342 0.0050611
01-Jan-1975 0.023011 0.01432 -0.0014045 -0.00051972 -0.0043703 0.011341 0.005376 0.0021556 -0.019326 -0.0046725 0.010182 0.004395 0.0017534 -0.0060605 -0.0011601 0.002806 0.011414 0.0045521 -0.004882 -0.0024604 -0.01291 -0.00094466 -0.00017957 -0.00068506 -0.021662 -0.011 0.0035604 0.0011887 -0.0069887 -0.01257 -0.0045524 -0.00041328 0.029914 0.016987 0.0018906 0.0011012 0.0051311 0.013943 0.0080383 0.0041762 -0.0068581 0.003094 0.012053 0.0057324 0.0082731 0.0013124 0.0025533 0.0042406
01-Apr-1975 0.019864 0.01344 -0.0014933 -4.4254e-06 -0.0078183 0.0062247 0.0050662 0.0027626 -0.025548 -0.0070059 0.009493 0.0043074 0.0045597 -0.004589 -0.002223 0.0011591 0.0063539 0.0025976 -0.0054684 -0.0021938 -0.017355 -0.0064979 -0.00123 0.00010743 -0.029292 -0.013974 0.0015562 0.00077995 -0.0081444 -0.011287 -0.0062556 -0.0022002 0.028924 0.015926 0.0014925 0.0012851 0.0059606 0.011209 0.0080886 0.0047651 -0.0063978 0.0028959 0.012097 0.0057966 0.014418 0.0038715 0.0033635 0.0023838
01-Jul-1975 0.019419 0.011244 -0.0015969 -3.4305e-05 -0.010187 0.0028147 0.0039998 0.0026985 -0.029124 -0.0084906 0.0084798 0.0037481 0.0077423 -0.0025063 -0.0026634 -0.00013404 0.005327 -0.00049621 -0.0054593 -0.0021455 -0.022716 -0.0081187 -0.0028733 -0.00042378 -0.034992 -0.015799 0.00056474 0.00020164 -0.0078458 -0.010846 -0.0068023 -0.0035519 0.029407 0.014405 0.001692 0.0015767 0.0087664 0.010134 0.0075162 0.0043343 -0.0057691 0.0018746 0.012047 0.0055231 0.020043 0.0064893 0.0029097 0.001343
01-Oct-1975 0.018532 0.01016 -0.0019436 -0.00013964 -0.010448 0.00049217 0.0028587 0.0021692 -0.031107 -0.0092773 0.0074784 0.0031474 0.0097242 -0.00029442 -0.0026358 -0.00082626 0.001818 -0.0004023 -0.0058779 -0.0022755 -0.023734 -0.0077482 -0.0042795 -0.00098779 -0.038594 -0.016547 -0.00011469 -0.00064435 -0.0095859 -0.0070065 -0.0059945 -0.0034737 0.030136 0.013705 0.0016763 0.0017479 0.011566 0.0082498 0.0057995 0.0033017 -0.0044473 0.0013279 0.011642 0.0050999 0.022978 0.0090112 0.0027824 0.0014644
01-Jan-1976 0.018426 0.0092868 -0.0022099 -0.00036763 -0.0097658 -0.00071481 0.0018519 0.0015618 -0.032019 -0.0098054 0.0066319 0.002661 0.010735 0.0013489 -0.0022958 -0.001066 0.00094487 -0.0010919 -0.0057706 -0.0026426 -0.023367 -0.0091729 -0.0049467 -0.0014946 -0.042002 -0.016681 -0.00084973 -0.0010919 -0.010268 -0.0059067 -0.0046107 -0.0030697 0.030831 0.014467 0.0020979 0.0014645 0.013995 0.0070356 0.0042604 0.0028084 -0.0042527 0.0021613 0.010919 0.0047273 0.024747 0.010363 0.0021819 0.00073538
01-Apr-1976 0.018347 0.0088274 -0.002408 -0.00055954 -0.0085284 -0.0013241 0.0011035 0.001029 -0.032301 -0.010245 0.0059331 0.0023208 0.010834 0.0024299 -0.0018575 -0.0010181 0.00088792 -0.00087384 -0.0057043 -0.0027239 -0.022321 -0.0095626 -0.0046415 -0.0016955 -0.044772 -0.015403 -0.0014757 -0.00074988 -0.010505 -0.0057904 -0.0042961 -0.0025666 0.030874 0.015059 0.0021942 0.0012385 0.01511 0.0075202 0.0041588 0.0022807 -0.0018926 0.0020667 0.0099711 0.0041106 0.027227 0.010447 0.0026554 0.0011517
01-Jul-1976 0.018349 0.0085007 -0.0025003 -0.00070381 -0.0072023 -0.0015783 0.00059083 0.00064004 -0.032139 -0.010662 0.0053454 0.0020863 0.010389 0.0030152 -0.0014396 -0.00084984 0.00081535 -0.00056917 -0.0054989 -0.0027904 -0.020095 -0.0090132 -0.003905 -0.0019258 -0.046259 -0.016859 -0.0018945 -0.0010315 -0.0088981 -0.0047543 -0.0042238 -0.0017878 0.030856 0.014085 0.0023174 0.0013691 0.017564 0.0079639 0.0040872 0.0017655 -0.001588 0.0020803 0.0088559 0.0036667 0.02646 0.010048 0.0026267 0.0012534
01-Oct-1976 0.018261 0.0082681 -0.0025175 -0.00078515 -0.0059528 -0.0016715 0.000265 0.00038128 -0.031642 -0.01103 0.0048331 0.0019104 0.0096565 0.0032746 -0.0011032 -0.00066034 -0.0011251 -0.00075733 -0.0050727 -0.0026529 -0.019957 -0.0091831 -0.0037003 -0.0015265 -0.046571 -0.018406 -0.0023099 -0.0010146 -0.0087836 -0.0043276 -0.0035229 -0.0015206 0.031925 0.013921 0.0023499 0.0013534 0.017285 0.0080779 0.0037871 0.0016071 0.00034958 0.0018116 0.0082019 0.0031525 0.025188 0.0098717 0.0023763 0.001372
01-Jan-1977 0.018088 0.0080578 -0.0024803 -0.00082067 -0.004866 -0.0016783 6.7351e-05 0.00021975 -0.030874 -0.011308 0.0043776 0.0017587 0.0088385 0.0033353 -0.00085828 -0.00049952 -0.0023654 -0.00054861 -0.0046959 -0.0023017 -0.018881 -0.0083688 -0.0036323 -0.0013151 -0.045822 -0.019143 -0.0022457 -0.00076165 -0.0096651 -0.0046474 -0.0033535 -0.001605 0.031832 0.013992 0.0023109 0.0011487 0.01618 0.0079136 0.0033058 0.0015065 0.0014169 0.0019553 0.0074233 0.0026903 0.023693 0.0092439 0.0022507 0.0010427
01-Apr-1977 0.01782 0.0078585 -0.0024126 -0.00082488 -0.0039472 -0.0016348 -4.6051e-05 0.00012029 -0.029898 -0.011467 0.0039728 0.0016154 0.0080434 0.0032901 -0.00069265 -0.00038034 -0.0041445 -0.0009108 -0.0046233 -0.0021475 -0.017842 -0.0074943 -0.0036166 -0.0012714 -0.044148 -0.019166 -0.0023327 -0.00078836 -0.010263 -0.0046773 -0.0028019 -0.001797 0.030983 0.013903 0.0022172 0.001152 0.014886 0.007478 0.0027978 0.0013601 0.0017628 0.0019984 0.0059992 0.0024748 0.023083 0.0093155 0.0021594 0.00090656
01-Jul-1977 0.01748 0.0076612 -0.0023288 -0.00081178 -0.0031853 -0.0015527 -0.00010551 5.8177e-05 -0.028778 -0.011497 0.0036184 0.001477 0.007324 0.0031905 -0.00058632 -0.00029882 -0.0055294 -0.00154 -0.0045625 -0.0019225 -0.017729 -0.00744 -0.0034336 -0.0012351 -0.041703 -0.018635 -0.0029266 -0.00097794 -0.010567 -0.004571 -0.0030526 -0.00144 0.029897 0.013651 0.002083 0.0011265 0.015725 0.0067952 0.0028631 0.0012628 0.0032766 0.0021382 0.0054534 0.00231 0.021 0.0091161 0.00197 0.000865
01-Oct-1977 0.017084 0.0074669 -0.0022386 -0.00078982 -0.0025611 -0.0014412 -0.00012965 1.837e-05 -0.027577 -0.01141 0.003315 0.0013467 0.0066953 0.0030638 -0.00052096 -0.00024515 -0.0059883 -0.0019006 -0.0045009 -0.0017518 -0.016735 -0.0070905 -0.0030476 -0.0012138 -0.03866 -0.017655 -0.0023904 -0.0010579 -0.010714 -0.0044868 -0.0030057 -0.0010935 0.028693 0.01332 0.0015194 0.0010569 0.016655 0.0061735 0.0029008 0.0010539 0.0049304 0.0023071 0.0052074 0.0022951 0.019005 0.008691 0.0018979 0.00088102
01-Jan-1978 0.016649 0.007275 -0.0021468 -0.00076393 -0.0020585 -0.0013098 -0.00013023 -6.9227e-06 -0.02635 -0.011223 0.0030608 0.0012284 0.006156 0.0029232 -0.00048251 -0.00021015 -0.0067654 -0.0016931 -0.0044291 -0.0016366 -0.016779 -0.0072429 -0.0028373 -0.0011991 -0.035195 -0.016242 -0.0025182 -0.0010499 -0.010659 -0.0043064 -0.002775 -0.0010409 0.028206 0.01294 0.0015156 0.00095142 0.016305 0.0058332 0.0026818 0.00094436 0.0054449 0.0022641 0.0053236 0.0021337 0.018369 0.0079906 0.0017187 0.00082592
01-Apr-1978 0.016187 0.0070851 -0.0020565 -0.00073641 -0.0016627 -0.0011692 -0.00011514 -2.1687e-05 -0.025141 -0.010963 0.0028515 0.001125 0.0056974 0.0027764 -0.00046133 -0.00018714 -0.0053812 -0.0015885 -0.0043428 -0.0016435 -0.016571 -0.007324 -0.0025033 -0.0011496 -0.033556 -0.015142 -0.0025535 -0.0010552 -0.010407 -0.0040787 -0.0025947 -0.0011176 0.027675 0.012605 0.0015485 0.00082164 0.015764 0.0056146 0.0024931 0.0010281 0.0054922 0.0019958 0.0054463 0.0021499 0.019244 0.0078422 0.00157 0.00071951
⋮

`Tbl`

is a timetable with 20 rows, representing the periods in the IRF, and 12 variables. Each variable is a 20-by-4 matrix of the IRF or confidence bound associated with a variable in the model `EstMdl`

. For example, `Tbl.M2_IRF(:,2)`

is the IRF of `M2`

resulting from a one-standard-deviation shock on `01-Jul-1974`

(period 0) to `Mdl.SeriesNames(2)`

, which is the variable `Y`

. [`Tbl.M2_IRF_LowerBound(:,2)`

,`Tbl.M2_IRF_UpperBound(:,2)`

] are the corresponding 95% confidence intervals.

Plot the IRF of M2 and its 95% confidence interval resulting from a one-standard-deviation shock on `01-Jul-1974`

(period 0) to `Mdl.SeriesNames(2)`

, which is the variable `Y`

.

idxM2 = startsWith(Tbl.Properties.VariableNames,"M2"); M2IRF = Tbl(:,idxM2); shockIdx = 2; figure hold on plot(M2IRF.Time,M2IRF.M2_IRF(:,shockIdx),"-o") plot(M2IRF.Time,[M2IRF.M2_IRF_LowerBound(:,shockIdx) ... M2IRF.M2_IRF_UpperBound(:,shockIdx)],"-o",Color="r") legend("IRF","95% confidence interval") title('M2 IRF, Shock to Y') hold off

### Monte Carlo Confidence Intervals on True IRF

Consider the 4-D VAR(2) model in Specify Data in Numeric Matrix When Plotting IRF. Estimate and plot its orthogonalized IRF and 95% Monte Carlo confidence intervals on the true IRF.

Load the Danish money and income data set, then estimate the VAR(2) model.

```
load Data_JDanish
Mdl = varm(4,2);
Mdl.SeriesNames = DataTable.Properties.VariableNames;
Mdl = estimate(Mdl,DataTable.Series);
```

Estimate the IRF and corresponding 95% Monte Carlo confidence intervals from the estimated VAR(2) model.

```
rng(1); % For reproducibility
[Response,Lower,Upper] = irf(Mdl);
```

`Response`

, `Lower`

, and `Upper`

are 20-by-4-by-4 arrays representing the orthogonalized IRF of `Mdl`

and corresponding lower and upper bounds of the confidence intervals. For all arrays, rows correspond to consecutive time points from time 0 to 19, columns correspond to variables receiving a one-standard-deviation innovation shock at time 0, and pages correspond to responses of variables to the variable being shocked. `Mdl.SeriesNames`

specifies the variable order.

Plot the orthogonalized IRF with its confidence bounds of the bond rate when real income is shocked at time 0.

irfshock2resp3 = Response(:,2,3); IRFCIShock2Resp3 = [Lower(:,2,3) Upper(:,2,3)]; figure; h1 = plot(0:19,irfshock2resp3); hold on h2 = plot(0:19,IRFCIShock2Resp3,"r--"); legend([h1 h2(1)],["IRF" "95% Confidence Interval"]) xlabel("Time Index"); ylabel("Response"); title("IRF of IB When Y Is Shocked"); grid on hold off

The effect of the impulse to real income on the bond rate fades after 10 periods.

### Bootstrap Confidence Intervals on True IRF

Consider the 4-D VAR(2) model in Specify Data in Numeric Matrix When Plotting IRF. Estimate and plot its orthogonalized IRF and 90% bootstrap confidence intervals on the true IRF.

Load the Danish money and income data set, and then estimate the VAR(2) model. Return the residuals from model estimation.

load Data_JDanish Mdl = varm(4,2); Mdl.SeriesNames = DataTable.Properties.VariableNames; [Mdl,~,~,Res] = estimate(Mdl,DataTable.Series); T = size(DataTable,1) % Total sample size

T = 55

`n = size(Res,1) % Effective sample size`

n = 53

`Res`

is a 53-by-4 array of residuals. Columns correspond to the variables in `Mdl.SeriesNames`

. The `estimate`

function requires `Mdl.P`

= 2 observations to initialize a VAR(2) model for estimation. Because presample data (`Y0`

) is unspecified, `estimate`

takes the first two observations in the specified response data to initialize the model. Therefore, the resulting effective sample size is `T`

– `Mdl.P`

= 53, and rows of `Res`

correspond to the observation indices 3 through `T`

.

Estimate the orthogonalized IRF and corresponding 90% bootstrap confidence intervals from the estimated VAR(2) model. Draw 500 paths of length `n`

from the series of residuals.

```
rng(1); % For reproducibility
[Response,Lower,Upper] = irf(Mdl,E=Res,NumPaths=500,Confidence=0.9);
```

Plot the orthogonalized IRF with its confidence bounds of the bond rate when real income is shocked at time 0.

irfshock2resp3 = Response(:,2,3); IRFCIShock2Resp3 = [Lower(:,2,3) Upper(:,2,3)]; figure; h1 = plot(0:19,irfshock2resp3); hold on h2 = plot(0:19,IRFCIShock2Resp3,"r--"); legend([h1 h2(1)],["IRF" "90% confidence interval"]) xlabel("Time Index") ylabel("Response") title("IRF of IB When Y Is Shocked"); grid on hold off

The effect of the impulse to real income on the bond rate fades after 10 periods.

## Input Arguments

`Mdl`

— VAR model

`varm`

model object

VAR model, specified as a `varm`

model object created by `varm`

or `estimate`

. `Mdl`

must be fully specified.

If `Mdl`

is an estimated model (returned by `estimate`

) , you must supply any optional data using the same data type as the input response data, to which the model is fit.

If `Mdl`

is a custom `varm`

model object (an object not returned by `estimate`

or modified after estimation), `irf`

can require a sample size for the simulation `SampleSize`

or presample responses `Y0`

.

### 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: **`irf(Mdl,NumObs=10,Method="generalized")`

specifies estimating
a generalized IRF for 10 time points starting at time 0, during which
`irf`

applies the shock.

**Options for All IRFs**

`NumObs`

— Number of periods

`20`

(default) | positive integer

Number of periods for which `irf`

computes
the IRF, specified as a positive integer.
`NumObs`

specifies the number of
observations to include in the IRF (the number of rows in
`Response`

or
`Tbl`

).

**Example: **`NumObs=10`

specifies the inclusion of 10
time points in the IRF starting at time 0, during which
`irf`

applies the shock,
and ending at period 9.

**Data Types: **`double`

`Method`

— IRF computation method

`"orthogonalized"`

(default) | `"generalized"`

| character vector

IRF computation method, specified as a value in this table.

Value | Description |
---|---|

`"orthogonalized"` | Compute impulse responses using orthogonalized,
one-standard-deviation innovation shocks.
`irf` uses the Cholesky factorization of
`Mdl.Covariance` for orthogonalization. |

`"generalized"` | Compute impulse responses using one-standard-deviation innovation shocks. |

**Example: **`Method="generalized"`

**Data Types: **`string`

| `char`

**Options for Confidence Bound Estimation**

`NumPaths`

— Number of sample paths

`100`

(default) | positive integer

Number of sample paths (trials) to generate, specified as a positive integer.

**Example: **`NumPaths=1000`

generates `1000`

sample
paths from which the software derives the confidence bounds.

**Data Types: **`double`

`SampleSize`

— Number of observations for Monte Carlo simulation or bootstrap per sample path

positive integer

Number of observations for the Monte Carlo simulation or bootstrap per sample path, specified as a positive integer.

**Example: **If you specify `SampleSize=100`

and do not specify the
`E`

name-value argument, the software estimates confidence bounds
from `NumPaths`

random paths of length `100`

from
`Mdl`

.

**Example: **If you specify `SampleSize=100,E=Res`

, the software
resamples, with replacement, `100`

observations (rows) from
`Res`

to form a sample path of innovations to filter through
`Mdl`

. The software forms `NumPaths`

random
sample paths from which it derives confidence bounds.

**Data Types: **`double`

`Y0`

— Presample response data

numeric matrix

Presample response data that provides initial values for model estimation during the
simulation, specified as a `numpreobs`

-by-`numseries`

numeric matrix. Use `Y0`

only in the following situations:

`numpreobs`

is the number of presample observations.
`numseries`

is `Mdl.NumSeries`

, the dimensionality of the
input model.

Each row is a presample observation, and measurements in each row occur simultaneously.
The last row contains the latest presample observation. `numpreobs`

is the
number of specified presample responses and it must be at least `Mdl.P`

. If
you supply more rows than necessary, `irf`

uses the latest
`Mdl.P`

observations only.

`numseries`

is the dimensionality of the input VAR model
`Mdl.NumSeries`

. Columns must correspond to the response variables in
`Mdl.SeriesNames`

.

The following situations determine the default or whether presample response data is required.

**Data Types: **`double`

`Presample`

— Presample data

table | timetable

*Since R2022b*

Presample data that provides initial values for the model `Mdl`

,
specified as a table or timetable with `numprevars`

variables and
`numpreobs`

rows. Use `Presample`

only in the
following situations:

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

must be at least `Mdl.P`

.
If you supply more rows than necessary, `irf`

uses the latest
`Mdl.P`

observations only.

Each variable is a `numpreobs`

numeric vector representing one path.
To control presample variable selection, see the optional
`PresampleResponseVariables`

name-value argument.

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 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.

The following situations determine the default or whether presample response data is required.

If

`Mdl`

is an unmodified estimated model,`irf`

sets`Presample`

to the presample response data used for estimation by default (see the`Presample`

name-value argument of`estimate`

).If

`Mdl`

is a custom model (for example, you modify a model after estimation by using dot notation) and you return confidence bounds in the table or timetable`Tbl`

, you must specify`Presample`

.

`PresampleResponseVariables`

— Variables to select from `Presample`

to use for presample response data

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

*Since R2022b*

Variables to select from `Presample`

to use for presample data, specified
as one of the following data types:

String vector or cell vector of character vectors containing

`numseries`

variable names in`Presample.Properties.VariableNames`

A length

`numseries`

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

A length

`numprevars`

logical vector, where`PresampleResponseVariables(`

selects variable) = true`j`

from`j`

`Presample.Properties.VariableNames`

, and`sum(PresampleResponseVariables)`

is`numseries`

`PresampleResponseVariables`

applies only when you specify
`Presample`

.

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

).

`PresampleResponseNames`

does not need to contain the same names as in
`Mdl.SeriesNames`

; `irf`

uses the data in
selected variable `PresampleResponseVariables(`

as a presample for * j*)

`Mdl.SeriesNames(``j`

)

.If the number of variables in `Presample`

matches
`Mdl.NumSeries`

, the default specifies all variables in
`Presample`

. If the number of variables in `Presample`

exceeds `Mdl.NumSeries`

, the default matches variables in
`Presample`

to names in `Mdl.SeriesNames`

.

**Example: **`PresampleResponseVariables=["GDP" "CPI"]`

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

or
`PresampleResponseVariable=[1 3]`

selects the first and third table
variables for presample data.

**Data Types: **`double`

| `logical`

| `char`

| `cell`

| `string`

`X`

— Predictor data

numeric matrix

Predictor data *x _{t}* for
estimating the model regression component during the simulation, specified as a numeric matrix
containing

`numpreds`

columns. Use `X`

only in the following situations:

`numpreds`

is the number of predictor variables
(`size(Mdl.Beta,2)`

).

Each row corresponds to an observation, and measurements in each row
occur simultaneously. The last row contains the latest
observation. `X`

must have at least
`SampleSize`

rows. If you supply
more rows than necessary, `irf`

uses
only the latest observations. `irf`

does not use the regression component in the presample
period.

Columns correspond to individual predictor variables. All predictor variables are present in the regression component of each response equation.

To maintain model consistency when `irf`

estimates the confidence bounds, specify predictor data when `Mdl`

has a
regression component. If `Mdl`

is an estimated model, specify the predictor
data used during model estimation (see the `X`

name-value argument of `estimate`

).

By default, `irf`

excludes the regression
component from confidence bound estimation, regardless of its
presence in `Mdl`

.

**Data Types: **`double`

`E`

— Series of residuals *e*_{t} from which to draw bootstrap samples

numeric matrix

_{t}

Series of residuals from which to draw bootstrap samples, specified as a
`numperiods`

-by-`numseries`

numeric matrix.
`irf`

assumes that `E`

is free of serial
correlation. Use `E`

only in the following situations:

Each column is the residual series corresponding to the response series names in
`Mdl.SeriesNames`

.

Each row corresponds to a period in the FEVD and the corresponding confidence bounds.

If `Mdl`

is an estimated `varm`

model object (an object returned by `estimate`

), you can specify `E`

as the inferred
residuals from estimation (see the `E`

output argument of
`estimate`

or `infer`

).

By default, `irf`

derives confidence bounds by conducting a
Monte Carlo simulation.

**Data Types: **`double`

`InSample`

— Time series data

table | timetable

*Since R2022b*

Time series data containing `numvars`

variables, including
`numseries`

variables of residuals
*e _{t}* to bootstrap or

`numpreds`

predictor variables
*x*for the model regression component, specified as a table or timetable. Use

_{t}`InSample`

only in the
following situations:

Each variable is a single path of observations, which `irf`

applies to all `NumPaths`

sample paths. If you specify
`Presample`

, you must specify which variables are residuals and
predictors. See the `ResidualVariables`

and
`PredictorVariables`

name-value arguments.

Each row is an observation, and measurements in each row occur simultaneously.
`InSample`

must have at least `SampleSize`

rows. If you supply more rows than necessary, `irf`

uses only
the latest observations.

If `InSample`

is a timetable, the following conditions apply:

`InSample`

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

).The datetime vector

`InSample.Time`

must be ascending or descending.`Presample`

must immediately precede`InSample`

, with respect to the sampling frequency.

If `InSample`

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

By default, `irf`

derives confidence bounds by conducting a
Monte Carlo simulation and does not use the regression component, regardless of its
presence in `Mdl`

.

`ResidualVariables`

— Variables to select from `InSample`

to treat as residuals *e*_{t} for bootstrapping

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

_{t}

*Since R2022b*

Variables to select from `InSample`

to treat as residuals for
bootstrapping, specified as one of the following data types:

String vector or cell vector of character vectors containing

`numseries`

variable names in`InSample.Properties.VariableNames`

A length

`numseries`

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

A length

`numvars`

logical vector, where`ResidualVariables(`

selects variable) = true`j`

from`j`

`InSample.Properties.VariableNames`

, and`sum(ResidualVariables)`

is`numseries`

Regardless, selected residual variable

is the residual series for
`j`

`Mdl.SeriesNames(`

.* j*)

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

).

By default, `irf`

derives confidence bounds by conducting a
Monte Carlo simulation.

**Example: **```
ResidualVariables=["GDP_Residuals"
"CPI_Residuals"]
```

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

or
`ResidualVariable=[1 3]`

selects the first and third table variables as the
disturbance variables.

**Data Types: **`double`

| `logical`

| `char`

| `cell`

| `string`

`PredictorVariables`

— Variables to select from `InSample`

to treat as exogenous predictor variables *x*_{t}

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

_{t}

*Since R2022b*

Variables to select from `InSample`

to treat as exogenous predictor
variables *x _{t}*, specified as one of the following data types:

String vector or cell vector of character vectors containing

`numpreds`

variable names in`InSample.Properties.VariableNames`

A length

`numpreds`

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

A length

`numvars`

logical vector, where`PredictorVariables(`

selects variable) = true`j`

from`j`

`InSample.Properties.VariableNames`

, and`sum(PredictorVariables)`

is`numpreds`

Regardless, selected predictor variable

corresponds to the coefficients
`j`

`Mdl.Beta(:,`

.* j*)

`PredictorVariables`

applies only when you specify
`InSample`

.

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

).

By default, `irf`

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 as
the response variables.

**Data Types: **`double`

| `logical`

| `char`

| `cell`

| `string`

`Confidence`

— Confidence level

`0.95`

(default) | numeric scalar in [0,1]

Confidence level for the confidence bounds, specified as a numeric scalar in the interval [0,1].

For each period, randomly drawn confidence intervals cover the true response `100*Confidence`

% of the time.

The default value is `0.95`

, which implies that the confidence bounds represent 95% confidence intervals.

**Example: **`Confidence=0.9`

specifies 90% confidence
intervals.

**Data Types: **`double`

**Note**

`NaN`

values in`Y0`

,`X`

, and`E`

indicate missing data.`irf`

removes missing data from these arguments by list-wise deletion. For each argument, if a row contains at least one`NaN`

,`irf`

removes the entire row.List-wise deletion reduces the sample size, can create irregular time series, and can cause

`E`

and`X`

to be unsynchronized.`irf`

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

## Output Arguments

`Response`

— IRF

numeric array

IRF of each variable, returned as a
`numobs`

-by-`numseries`

-by-`numseries`

numeric array. `numobs`

is the value of `NumObs`

.
Columns and pages correspond to the response variables in
`Mdl.SeriesNames`

.

`irf`

returns `Response`

only in the
following situations:

You supply optional data inputs as numeric matrices.

`Mdl`

is an estimated model fit to a numeric matrix of response data.

`Response(`

is the
impulse response of variable * t* +
1,

*,*

`j`

*)*

`k`

`k`

at time
`t`

, attributable to a
one-standard-deviation innovation shock applied at time 0 to variable
`j`

, for
`t`

= 0, 1, ...,
`numObs`

– 1, `j`

=
1,2,...,`numseries`

, and
`k`

=
1,2,...,`numseries`

. For example,
`Response(1,2,3)`

is the impulse response of variable
`Mdl.SeriesName(3)`

at time
`t`

= 0, attributable to an innovation
shock applied at time 0 to `Mdl.SeriesName(2)`

.`Lower`

— Lower confidence bounds

numeric array

Lower confidence bounds, returned as a
`numobs`

-by-`numseries`

-by-`numseries`

numeric array. Elements of `Lower`

correspond to elements of
`Response`

.

`irf`

returns `Lower`

only in the
following situations:

You supply optional data inputs as numeric matrices.

`Mdl`

is an estimated model fit to a numeric matrix of response data.

`Lower(`

is the
lower bound of the * t* +
1,

*,*

`j`

*)*

`k`

`100*Confidence`

-th percentile interval on the
true impulse response of variable `k`

at
time `t`

, attributable to a
one-standard-deviation innovation shock applied at time 0 to variable
`j`

. For example,
`Lower(1,2,3)`

is the lower bound of the confidence interval on the
true impulse response of variable `Mdl.SeriesName(3)`

at time
`t`

= 0, attributable to an
innovation shock applied at time 0 to `Mdl.SeriesName(2)`

.`Upper`

— Upper confidence bounds

numeric array

Upper confidence bounds, returned as a
`numobs`

-by-`numseries`

-by-`numseries`

numeric array. Elements of `Upper`

correspond to elements of
`Response`

.

`irf`

returns `Upper`

only in the
following situations:

You supply optional data inputs as numeric matrices.

`Mdl`

is an estimated model fit to a numeric matrix of response data.

`Upper(`

is the
upper bound of the * t* +
1,

*,*

`j`

*)*

`k`

`100*Confidence`

-th percentile interval on the
true impulse response of variable `k`

attime
`t`

, attributable to a
one-standard-deviation innovation shock applied at time 0 to variable
`j`

. For example,
`Upper(1,2,3)`

is the upper bound of the confidence interval on the
true impulse response of variable `Mdl.SeriesName(3)`

at time
`t`

= 0, attributable to an
innovation shock applied at time 0 to `Mdl.SeriesName(2)`

.`Tbl`

— IRF and confidence bounds

table | timetable

*Since R2022b*

IRF and confidence bounds, returned as a table or timetable with
`numobs`

rows. `irf`

returns
`Tbl`

only in the following situations:

You supply optional data inputs as tables or timetables.

`Mdl`

is an estimated model fit to response data in a table or timetable.

Regardless, the data type of `Tbl`

is the same as the
data type of specified data.

`Tbl`

contains the following variables:

The IRF of each series in

*y*. Each IRF variable in_{t}`Tbl`

is a`numobs`

-by-`numseries`

numeric matrix, where`numobs`

is the value of`NumObs`

and`numseries`

is the value of`Mdl.NumSeries`

.`irf`

names the IRF of response variable

in`ResponseJ`

`Mdl.SeriesNames`

. For example, if_IRF`ResponseJ`

`Mdl.Series(`

is)`j`

`GDP`

,`Tbl`

contains a variable for the corresponding IRF with the name`GDP_IRF`

._IRF`ResponseJ`

`(`

is the impulse response of variable+ 1,`t`

)`k`

at time`ResponseJ`

, attributable to a one-standard-deviation innovation shock applied at time 0 to variable`t`

, for`k`

= 0,1, ...,`t`

`numObs`

– 1,

= 1,2,...,`J`

`numseries`

, and

= 1,2,...,`k`

`numseries`

.The lower and upper confidence bounds on the true IRF of the response series, when you set at least one name-value argument that controls the confidence bounds. Each confidence bound variable in

`Tbl`

is a`numobs`

-by-`numseries`

numeric matrix.

and_IRF_LowerBound`ResponseJ`

are the names of the lower and upper bound variables, respectively, of the confidence interval on the IRF of response variable_IRF_UpperBound`ResponseJ`

`Mdl.SeriesNames(`

=)`J`

. For example, if`ResponseJ`

`Mdl.SeriesNames(`

is)`j`

`GDP`

,`Tbl`

contains variables for the corresponding lower and upper bounds of the confidence interval with the name`GDP_IRF_LowerBound`

and`GDP_IRF_UpperBound`

.(

,_IRF_LowerBound(`ResponseJ`

,`t`

)`k`

) is the_IRF_UpperBound(`ResponseJ`

,`t`

)`k`

`100*`

`Confidence`

-th percentile confidence interval on the IRF of response variable

at time`ResponseJ`

, attributable to a one-standard-deviation innovation shock applied at time 0 to variable`t`

, for`k`

= 0,1,…,`t`

`numobs`

– 1,

= 1,2,...,`J`

`numseries`

, and

= 1,2,...,`k`

`numseries`

.

If `Tbl`

is a timetable, the row order of `Tbl`

,
either ascending or descending, matches the row order of `InSample`

,
when you specify it. If you do not specify `InSample`

and you specify
`Presample`

, the row order of `Tbl`

is the
same as the row order of `Presample`

.

## More About

### Impulse Response Function

An *impulse response function* (IRF) of a time
series model (or *dynamic response of the system*) measures the changes
in the future responses of all variables in the system when a variable is shocked by an
impulse. In other words, the IRF at time *t* is the derivative of the
responses at time *t* with respect to an innovation at time
*t*_{0} (the time that innovation was shocked),
*t* ≥ *t*_{0}.

Consider a `numseries`

-D VAR(*p*)
model for the multivariate response variable
*y _{t}*. In lag operator notation, the infinite lag
MA representation of

*y*is

_{t}$$\begin{array}{c}{y}_{t}={\Phi}^{-1}(L)\left(c+\beta {x}_{t}+\delta t\right)+{\Phi}^{-1}(L){\epsilon}_{t}\\ =\Omega (L)\left(c+\beta {x}_{t}+\delta t\right)+\Omega (L){\epsilon}_{t}.\end{array}$$

The general form of the IRF of *y _{t}* shocked by
an impulse to variable

*j*by one standard deviation of its innovation

*m*periods into the future is

$${\psi}_{j}(m)={C}_{m}{e}_{j}.$$

*e*is a selection vector of length_{j}`numseries`

containing a 1 in element*j*and zeros elsewhere.For the orthogonalized IRF, $${C}_{m}={\Omega}_{m}P,$$ where

*P*is the lower triangular factor in the Cholesky factorization of Σ, and Ω_{m}is the lag*m*coefficient of Ω(*L*).For the generalized IRF, $${C}_{m}={\sigma}_{j}^{-1}{\Omega}_{m}\Sigma ,$$ where σ

_{j}is the standard deviation of innovation*j*.The IRF is free of the model constant, regression component, and time trend.

### Vector Autoregression Model

A *vector autoregression (VAR) model* is a
stationary multivariate time series model consisting of a system of *m*
equations of *m* distinct response variables as linear functions of lagged
responses and other terms.

A VAR(*p*) model in *difference-equation notation*
and in *reduced form* is

$${y}_{t}=c+{\Phi}_{1}{y}_{t-1}+{\Phi}_{2}{y}_{t-2}+\mathrm{...}+{\Phi}_{p}{y}_{t-p}+\beta {x}_{t}+\delta t+{\epsilon}_{t}.$$

*y*is a_{t}`numseries`

-by-1 vector of values corresponding to`numseries`

response variables at time*t*, where*t*= 1,...,*T*. The structural coefficient is the identity matrix.*c*is a`numseries`

-by-1 vector of constants.Φ

_{j}is a`numseries`

-by-`numseries`

matrix of autoregressive coefficients, where*j*= 1,...,*p*and Φ_{p}is not a matrix containing only zeros.*x*is a_{t}`numpreds`

-by-1 vector of values corresponding to`numpreds`

exogenous predictor variables.*β*is a`numseries`

-by-`numpreds`

matrix of regression coefficients.*δ*is a`numseries`

-by-1 vector of linear time-trend values.*ε*is a_{t}`numseries`

-by-1 vector of random Gaussian innovations, each with a mean of 0 and collectively a`numseries`

-by-`numseries`

covariance matrix Σ. For*t*≠*s*,*ε*and_{t}*ε*are independent._{s}

Condensed and in lag operator notation, the system is

$$\Phi (L){y}_{t}=c+\beta {x}_{t}+\delta t+{\epsilon}_{t},$$

where $$\Phi (L)=I-{\Phi}_{1}L-{\Phi}_{2}{L}^{2}-\mathrm{...}-{\Phi}_{p}{L}^{p}$$, Φ(*L*)*y _{t}* is
the multivariate autoregressive polynomial, and

*I*is the

`numseries`

-by-`numseries`

identity matrix.## Algorithms

If

`Method`

is`"orthogonalized"`

, then the resulting IRF depends on the order of the variables in the time series model. If`Method`

is`"generalized"`

, then the resulting IRF is invariant to the order of the variables. Therefore, the two methods generally produce different results.If

`Mdl.Covariance`

is a diagonal matrix, then the resulting generalized and orthogonalized IRFs are identical. Otherwise, the resulting generalized and orthogonalized IRFs are identical only when the first variable shocks all variables (for example, all else being the same, both methods yield the same value of`Response(:,1,:)`

).The predictor data in

`X`

or`InSample`

represents a single path of exogenous multivariate time series. If you specify`X`

or`InSample`

and the model`Mdl`

has a regression component (`Mdl.Beta`

is not an empty array),`irf`

applies the same exogenous data to all paths used for confidence interval estimation.`irf`

conducts a simulation to estimate the confidence bounds`Lower`

and`Upper`

or associated variables in`Tbl`

.If you do not specify residuals by supplying

`E`

or using`InSample`

,`irf`

conducts a Monte Carlo simulation by following this procedure:Simulate

`NumPaths`

response paths of length`SampleSize`

from`Mdl`

.Fit

`NumPaths`

models that have the same structure as`Mdl`

to the simulated response paths. If`Mdl`

contains a regression component and you specify predictor data by supplying`X`

or using`InSample`

, then`irf`

fits the`NumPaths`

models to the simulated response paths and the same predictor data (the same predictor data applies to all paths).Estimate

`NumPaths`

IRFs from the`NumPaths`

estimated models.For each time point

*t*= 0,…,`NumObs`

, estimate the confidence intervals by computing 1 –`Confidence`

and`Confidence`

quantiles (upper and lower bounds, respectively).

Otherwise,

`irf`

conducts a nonparametric bootstrap by following this procedure:Resample, with replacement,

`SampleSize`

residuals from`E`

or`InSample`

. Perform this step`NumPaths`

times to obtain`NumPaths`

paths.Center each path of bootstrapped residuals.

Filter each path of centered, bootstrapped residuals through

`Mdl`

to obtain`NumPaths`

bootstrapped response paths of length`SampleSize`

.Complete steps 2 through 4 of the Monte Carlo simulation, but replace the simulated response paths with the bootstrapped response paths.

## References

[1]
Hamilton, James D. *Time Series Analysis*. Princeton, NJ: Princeton University Press, 1994.

[2]
Lütkepohl, Helmut. *New Introduction to Multiple Time Series Analysis*. New York, NY: Springer-Verlag, 2007.

[3]
Pesaran, H. H., and Y. Shin. "Generalized Impulse Response
Analysis in Linear Multivariate Models." *Economic Letters.* Vol. 58, 1998,
pp. 17–29.

## Version History

**Introduced in R2019a**

### R2022b: `irf`

accepts input data in tables and timetables, and return results in tables and timetables

In addition to accepting input data in numeric arrays,
`irf`

accepts input data in tables and timetables. `irf`

chooses default series on which to operate, but you can use the following name-value arguments to select variables.

`Presample`

specifies the input table or regular timetable of presample response data.`PresampleResponseVariables`

specifies the response series names from`Presample`

.`Insample`

specifies the table or regular timetable of residual and predictor data to compute bootstrap estimates.`ResidualVariables`

specifies the residual series names in`InSample`

.`PredictorVariables`

specifies the predictor series in`InSample`

for a model regression component.

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