This example shows the behavior of the software when you explicitly specify a time-varying state space model.
From periods 1 through 50, the state model is an AR(2) and an MA(1) model, and the observation model is the sum of the two states. From periods 51 through 100, the state model only includes the first AR(2) model. Symbolically, the state-space model is, from periods 1 through 50,
for period 51,
and for periods 52 through 100,
Specify the state-transition coefficient matrix.
A1 = {[NaN NaN 0 0; 1 0 0 0; 0 0 0 NaN; 0 0 0 0]};
A2 = {[NaN NaN 0 0; 1 0 0 0]};
A3 = {[NaN NaN; 1 0]};
A = [repmat(A1,50,1);A2;repmat(A3,49,1)];
Specify the state-disturbance-loading coefficient matrix.
B1 = {[NaN 0 0 0; 0 0 0 0; 0 0 1 0; 0 0 1 0]};
B2 = {[NaN 0 0 0; 0 0 0 0]};
B3 = {[NaN 0; 0 0]};
B = [repmat(B1,50,1);B2;repmat(B3,49,1)];
Specify the measurement-sensitivity coefficient matrix.
C1 = {[NaN 0 NaN 0]};
C3 = {[NaN 0]};
C = [repmat(C1,50,1);repmat(C3,50,1)];
Specify an empty matrix for the observation distrubance coefficient matrix.
D1 = {NaN};
D3 = {NaN};
D = [repmat(D1,50,1);repmat(D3,50,1)];
Specify the state-space model. Set the initial state means and covariance matrix to unknown parameters. Specify that the initial state distributions are stationary.
Mean0 = nan(4,1);
Cov0 = nan(4,4);
StateType = [0; 0; 0; 0];
Mdl = ssm(A,B,C,D,'Mean0',Mean0,'Cov0',Cov0,'StateType',StateType);
Mdl is an ssm model.
The model is large and it contains a different set of parameters for each period. The software displays state and observation equations for the first 10 and last 10 periods. You can choose which periods to display the equations for using the 'Period' name-value pair argument.
Display the state-space model, and specify to display the state and observation equations for the 50th, 51st, and 52nd periods.
disp(Mdl,'Period',50)
disp(Mdl,'Period',51)
disp(Mdl,'Period',52)
State vector length: Time-varying
Observation vector length: 1
State disturbance vector length: Time-varying
Observation innovation vector length: 1
Sample size supported by model: 100
Unknown parameters for estimation: 620
State variables: x1, x2,...
State disturbances: u1, u2,...
Observation series: y1, y2,...
Observation innovations: e1, e2,...
Unknown parameters: c1, c2,...
State equations (in period 50):
x1(t) = (c148)x1(t-1) + (c149)x2(t-1) + (c300)u1(t)
x2(t) = x1(t-1)
x3(t) = (c150)x4(t-1) + u3(t)
x4(t) = u3(t)
Time-varying transition matrix A contains unknown parameters:
c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 c11 c12 c13 c14 c15 c16 c17 c18 c19 c20
c21 c22 c23 c24 c25 c26 c27 c28 c29 c30 c31 c32 c33 c34 c35 c36 c37 c38 c39 c40
c41 c42 c43 c44 c45 c46 c47 c48 c49 c50 c51 c52 c53 c54 c55 c56 c57 c58 c59 c60
c61 c62 c63 c64 c65 c66 c67 c68 c69 c70 c71 c72 c73 c74 c75 c76 c77 c78 c79 c80
c81 c82 c83 c84 c85 c86 c87 c88 c89 c90 c91 c92 c93 c94 c95 c96 c97 c98 c99 c100
c101 c102 c103 c104 c105 c106 c107 c108 c109 c110 c111 c112 c113 c114 c115 c116 c117 c118 c119 c120
c121 c122 c123 c124 c125 c126 c127 c128 c129 c130 c131 c132 c133 c134 c135 c136 c137 c138 c139 c140
c141 c142 c143 c144 c145 c146 c147 c148 c149 c150 c151 c152 c153 c154 c155 c156 c157 c158 c159 c160
c161 c162 c163 c164 c165 c166 c167 c168 c169 c170 c171 c172 c173 c174 c175 c176 c177 c178 c179 c180
c181 c182 c183 c184 c185 c186 c187 c188 c189 c190 c191 c192 c193 c194 c195 c196 c197 c198 c199 c200
c201 c202 c203 c204 c205 c206 c207 c208 c209 c210 c211 c212 c213 c214 c215 c216 c217 c218 c219 c220
c221 c222 c223 c224 c225 c226 c227 c228 c229 c230 c231 c232 c233 c234 c235 c236 c237 c238 c239 c240
c241 c242 c243 c244 c245 c246 c247 c248 c249 c250
Time-varying state disturbance loading matrix B contains unknown parameters:
c251 c252 c253 c254 c255 c256 c257 c258 c259 c260 c261 c262 c263 c264 c265 c266 c267 c268 c269 c270
c271 c272 c273 c274 c275 c276 c277 c278 c279 c280 c281 c282 c283 c284 c285 c286 c287 c288 c289 c290
c291 c292 c293 c294 c295 c296 c297 c298 c299 c300 c301 c302 c303 c304 c305 c306 c307 c308 c309 c310
c311 c312 c313 c314 c315 c316 c317 c318 c319 c320 c321 c322 c323 c324 c325 c326 c327 c328 c329 c330
c331 c332 c333 c334 c335 c336 c337 c338 c339 c340 c341 c342 c343 c344 c345 c346 c347 c348 c349 c350
Observation equation (in period 50):
y1(t) = (c449)x1(t) + (c450)x3(t) + (c550)e1(t)
Time-varying measurement sensitivity matrix C contains unknown parameters:
c351 c352 c353 c354 c355 c356 c357 c358 c359 c360 c361 c362 c363 c364 c365 c366 c367 c368 c369 c370
c371 c372 c373 c374 c375 c376 c377 c378 c379 c380 c381 c382 c383 c384 c385 c386 c387 c388 c389 c390
c391 c392 c393 c394 c395 c396 c397 c398 c399 c400 c401 c402 c403 c404 c405 c406 c407 c408 c409 c410
c411 c412 c413 c414 c415 c416 c417 c418 c419 c420 c421 c422 c423 c424 c425 c426 c427 c428 c429 c430
c431 c432 c433 c434 c435 c436 c437 c438 c439 c440 c441 c442 c443 c444 c445 c446 c447 c448 c449 c450
c451 c452 c453 c454 c455 c456 c457 c458 c459 c460 c461 c462 c463 c464 c465 c466 c467 c468 c469 c470
c471 c472 c473 c474 c475 c476 c477 c478 c479 c480 c481 c482 c483 c484 c485 c486 c487 c488 c489 c490
c491 c492 c493 c494 c495 c496 c497 c498 c499 c500
Time-varying observation innovation loading matrix D contains unknown parameters:
c501 c502 c503 c504 c505 c506 c507 c508 c509 c510 c511 c512 c513 c514 c515 c516 c517 c518 c519 c520
c521 c522 c523 c524 c525 c526 c527 c528 c529 c530 c531 c532 c533 c534 c535 c536 c537 c538 c539 c540
c541 c542 c543 c544 c545 c546 c547 c548 c549 c550 c551 c552 c553 c554 c555 c556 c557 c558 c559 c560
c561 c562 c563 c564 c565 c566 c567 c568 c569 c570 c571 c572 c573 c574 c575 c576 c577 c578 c579 c580
c581 c582 c583 c584 c585 c586 c587 c588 c589 c590 c591 c592 c593 c594 c595 c596 c597 c598 c599 c600
Initial state distribution:
Initial state means
x1 x2 x3 x4
NaN NaN NaN NaN
Initial state covariance matrix
x1 x2 x3 x4
x1 NaN NaN NaN NaN
x2 NaN NaN NaN NaN
x3 NaN NaN NaN NaN
x4 NaN NaN NaN NaN
State types
x1 x2 x3 x4
Stationary Stationary Stationary Stationary
State vector length: Time-varying
Observation vector length: 1
State disturbance vector length: Time-varying
Observation innovation vector length: 1
Sample size supported by model: 100
Unknown parameters for estimation: 620
State variables: x1, x2,...
State disturbances: u1, u2,...
Observation series: y1, y2,...
Observation innovations: e1, e2,...
Unknown parameters: c1, c2,...
State equations (in period 51):
x1(t) = (c151)x1(t-1) + (c152)x2(t-1) + (c301)u1(t)
x2(t) = x1(t-1)
Time-varying transition matrix A contains unknown parameters:
c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 c11 c12 c13 c14 c15 c16 c17 c18 c19 c20
c21 c22 c23 c24 c25 c26 c27 c28 c29 c30 c31 c32 c33 c34 c35 c36 c37 c38 c39 c40
c41 c42 c43 c44 c45 c46 c47 c48 c49 c50 c51 c52 c53 c54 c55 c56 c57 c58 c59 c60
c61 c62 c63 c64 c65 c66 c67 c68 c69 c70 c71 c72 c73 c74 c75 c76 c77 c78 c79 c80
c81 c82 c83 c84 c85 c86 c87 c88 c89 c90 c91 c92 c93 c94 c95 c96 c97 c98 c99 c100
c101 c102 c103 c104 c105 c106 c107 c108 c109 c110 c111 c112 c113 c114 c115 c116 c117 c118 c119 c120
c121 c122 c123 c124 c125 c126 c127 c128 c129 c130 c131 c132 c133 c134 c135 c136 c137 c138 c139 c140
c141 c142 c143 c144 c145 c146 c147 c148 c149 c150 c151 c152 c153 c154 c155 c156 c157 c158 c159 c160
c161 c162 c163 c164 c165 c166 c167 c168 c169 c170 c171 c172 c173 c174 c175 c176 c177 c178 c179 c180
c181 c182 c183 c184 c185 c186 c187 c188 c189 c190 c191 c192 c193 c194 c195 c196 c197 c198 c199 c200
c201 c202 c203 c204 c205 c206 c207 c208 c209 c210 c211 c212 c213 c214 c215 c216 c217 c218 c219 c220
c221 c222 c223 c224 c225 c226 c227 c228 c229 c230 c231 c232 c233 c234 c235 c236 c237 c238 c239 c240
c241 c242 c243 c244 c245 c246 c247 c248 c249 c250
Time-varying state disturbance loading matrix B contains unknown parameters:
c251 c252 c253 c254 c255 c256 c257 c258 c259 c260 c261 c262 c263 c264 c265 c266 c267 c268 c269 c270
c271 c272 c273 c274 c275 c276 c277 c278 c279 c280 c281 c282 c283 c284 c285 c286 c287 c288 c289 c290
c291 c292 c293 c294 c295 c296 c297 c298 c299 c300 c301 c302 c303 c304 c305 c306 c307 c308 c309 c310
c311 c312 c313 c314 c315 c316 c317 c318 c319 c320 c321 c322 c323 c324 c325 c326 c327 c328 c329 c330
c331 c332 c333 c334 c335 c336 c337 c338 c339 c340 c341 c342 c343 c344 c345 c346 c347 c348 c349 c350
Observation equation (in period 51):
y1(t) = (c451)x1(t) + (c551)e1(t)
Time-varying measurement sensitivity matrix C contains unknown parameters:
c351 c352 c353 c354 c355 c356 c357 c358 c359 c360 c361 c362 c363 c364 c365 c366 c367 c368 c369 c370
c371 c372 c373 c374 c375 c376 c377 c378 c379 c380 c381 c382 c383 c384 c385 c386 c387 c388 c389 c390
c391 c392 c393 c394 c395 c396 c397 c398 c399 c400 c401 c402 c403 c404 c405 c406 c407 c408 c409 c410
c411 c412 c413 c414 c415 c416 c417 c418 c419 c420 c421 c422 c423 c424 c425 c426 c427 c428 c429 c430
c431 c432 c433 c434 c435 c436 c437 c438 c439 c440 c441 c442 c443 c444 c445 c446 c447 c448 c449 c450
c451 c452 c453 c454 c455 c456 c457 c458 c459 c460 c461 c462 c463 c464 c465 c466 c467 c468 c469 c470
c471 c472 c473 c474 c475 c476 c477 c478 c479 c480 c481 c482 c483 c484 c485 c486 c487 c488 c489 c490
c491 c492 c493 c494 c495 c496 c497 c498 c499 c500
Time-varying observation innovation loading matrix D contains unknown parameters:
c501 c502 c503 c504 c505 c506 c507 c508 c509 c510 c511 c512 c513 c514 c515 c516 c517 c518 c519 c520
c521 c522 c523 c524 c525 c526 c527 c528 c529 c530 c531 c532 c533 c534 c535 c536 c537 c538 c539 c540
c541 c542 c543 c544 c545 c546 c547 c548 c549 c550 c551 c552 c553 c554 c555 c556 c557 c558 c559 c560
c561 c562 c563 c564 c565 c566 c567 c568 c569 c570 c571 c572 c573 c574 c575 c576 c577 c578 c579 c580
c581 c582 c583 c584 c585 c586 c587 c588 c589 c590 c591 c592 c593 c594 c595 c596 c597 c598 c599 c600
Initial state distribution:
Initial state means
x1 x2 x3 x4
NaN NaN NaN NaN
Initial state covariance matrix
x1 x2 x3 x4
x1 NaN NaN NaN NaN
x2 NaN NaN NaN NaN
x3 NaN NaN NaN NaN
x4 NaN NaN NaN NaN
State types
x1 x2 x3 x4
Stationary Stationary Stationary Stationary
State vector length: Time-varying
Observation vector length: 1
State disturbance vector length: Time-varying
Observation innovation vector length: 1
Sample size supported by model: 100
Unknown parameters for estimation: 620
State variables: x1, x2,...
State disturbances: u1, u2,...
Observation series: y1, y2,...
Observation innovations: e1, e2,...
Unknown parameters: c1, c2,...
State equations (in period 52):
x1(t) = (c153)x1(t-1) + (c154)x2(t-1) + (c302)u1(t)
x2(t) = x1(t-1)
Time-varying transition matrix A contains unknown parameters:
c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 c11 c12 c13 c14 c15 c16 c17 c18 c19 c20
c21 c22 c23 c24 c25 c26 c27 c28 c29 c30 c31 c32 c33 c34 c35 c36 c37 c38 c39 c40
c41 c42 c43 c44 c45 c46 c47 c48 c49 c50 c51 c52 c53 c54 c55 c56 c57 c58 c59 c60
c61 c62 c63 c64 c65 c66 c67 c68 c69 c70 c71 c72 c73 c74 c75 c76 c77 c78 c79 c80
c81 c82 c83 c84 c85 c86 c87 c88 c89 c90 c91 c92 c93 c94 c95 c96 c97 c98 c99 c100
c101 c102 c103 c104 c105 c106 c107 c108 c109 c110 c111 c112 c113 c114 c115 c116 c117 c118 c119 c120
c121 c122 c123 c124 c125 c126 c127 c128 c129 c130 c131 c132 c133 c134 c135 c136 c137 c138 c139 c140
c141 c142 c143 c144 c145 c146 c147 c148 c149 c150 c151 c152 c153 c154 c155 c156 c157 c158 c159 c160
c161 c162 c163 c164 c165 c166 c167 c168 c169 c170 c171 c172 c173 c174 c175 c176 c177 c178 c179 c180
c181 c182 c183 c184 c185 c186 c187 c188 c189 c190 c191 c192 c193 c194 c195 c196 c197 c198 c199 c200
c201 c202 c203 c204 c205 c206 c207 c208 c209 c210 c211 c212 c213 c214 c215 c216 c217 c218 c219 c220
c221 c222 c223 c224 c225 c226 c227 c228 c229 c230 c231 c232 c233 c234 c235 c236 c237 c238 c239 c240
c241 c242 c243 c244 c245 c246 c247 c248 c249 c250
Time-varying state disturbance loading matrix B contains unknown parameters:
c251 c252 c253 c254 c255 c256 c257 c258 c259 c260 c261 c262 c263 c264 c265 c266 c267 c268 c269 c270
c271 c272 c273 c274 c275 c276 c277 c278 c279 c280 c281 c282 c283 c284 c285 c286 c287 c288 c289 c290
c291 c292 c293 c294 c295 c296 c297 c298 c299 c300 c301 c302 c303 c304 c305 c306 c307 c308 c309 c310
c311 c312 c313 c314 c315 c316 c317 c318 c319 c320 c321 c322 c323 c324 c325 c326 c327 c328 c329 c330
c331 c332 c333 c334 c335 c336 c337 c338 c339 c340 c341 c342 c343 c344 c345 c346 c347 c348 c349 c350
Observation equation (in period 52):
y1(t) = (c452)x1(t) + (c552)e1(t)
Time-varying measurement sensitivity matrix C contains unknown parameters:
c351 c352 c353 c354 c355 c356 c357 c358 c359 c360 c361 c362 c363 c364 c365 c366 c367 c368 c369 c370
c371 c372 c373 c374 c375 c376 c377 c378 c379 c380 c381 c382 c383 c384 c385 c386 c387 c388 c389 c390
c391 c392 c393 c394 c395 c396 c397 c398 c399 c400 c401 c402 c403 c404 c405 c406 c407 c408 c409 c410
c411 c412 c413 c414 c415 c416 c417 c418 c419 c420 c421 c422 c423 c424 c425 c426 c427 c428 c429 c430
c431 c432 c433 c434 c435 c436 c437 c438 c439 c440 c441 c442 c443 c444 c445 c446 c447 c448 c449 c450
c451 c452 c453 c454 c455 c456 c457 c458 c459 c460 c461 c462 c463 c464 c465 c466 c467 c468 c469 c470
c471 c472 c473 c474 c475 c476 c477 c478 c479 c480 c481 c482 c483 c484 c485 c486 c487 c488 c489 c490
c491 c492 c493 c494 c495 c496 c497 c498 c499 c500
Time-varying observation innovation loading matrix D contains unknown parameters:
c501 c502 c503 c504 c505 c506 c507 c508 c509 c510 c511 c512 c513 c514 c515 c516 c517 c518 c519 c520
c521 c522 c523 c524 c525 c526 c527 c528 c529 c530 c531 c532 c533 c534 c535 c536 c537 c538 c539 c540
c541 c542 c543 c544 c545 c546 c547 c548 c549 c550 c551 c552 c553 c554 c555 c556 c557 c558 c559 c560
c561 c562 c563 c564 c565 c566 c567 c568 c569 c570 c571 c572 c573 c574 c575 c576 c577 c578 c579 c580
c581 c582 c583 c584 c585 c586 c587 c588 c589 c590 c591 c592 c593 c594 c595 c596 c597 c598 c599 c600
Initial state distribution:
Initial state means
x1 x2 x3 x4
NaN NaN NaN NaN
Initial state covariance matrix
x1 x2 x3 x4
x1 NaN NaN NaN NaN
x2 NaN NaN NaN NaN
x3 NaN NaN NaN NaN
x4 NaN NaN NaN NaN
State types
x1 x2 x3 x4
Stationary Stationary Stationary Stationary
The software attributes a different set of coefficients for each period. You might experience numerical issues when you estimate such models. To reuse parameters among groups of periods, consider creating a parameter-to-matrix mapping function.