Dynamic IRT with random-walk priors (stub) — morie_spatial_voting_dynamic

Time-series IRT where ideal points evolve via a random walk: \(\phi_{i,t} \sim N(\phi_{i,t-1}, \tau^2)\).

Usage

morie_spatial_voting_dynamic_irt(
  votes,
  time_periods,
  n_samples = 500L,
  burn_in = 100L,
  seed = 42L
)

Arguments

votes: Vote matrix. @param time_periods Per-vote period indices.
time_periods: Integer vector of period indices (one per roll call) for the dynamic-IRT random-walk prior on ideal points.
n_samples: MCMC samples. @param burn_in Burn-in length.
burn_in: Integer; MCMC burn-in iterations.
seed: RNG seed.

Value

List of per-period ideal-point matrices with an engine tag flagging the per-period EM approximation.

References

Martin, A. D. and Quinn, K. M. (2002). "Dynamic Ideal Point Estimation via Markov Chain Monte Carlo for the U.S. Supreme Court, 1953-1999." Political Analysis, 10(2).

Examples

morie_spatial_voting_dynamic_irt(matrix(0, 4, 4), 1:4)
#> $per_period
#> $per_period$`1`
#> $per_period$`1`$period
#> [1] 1
#> 
#> $per_period$`1`$ideal_points
#>             [,1]
#> [1,]  0.58716913
#> [2,] -0.36851679
#> [3,]  0.08946095
#> [4,]  0.22264344
#> 
#> $per_period$`1`$discrimination
#>            [,1]
#> [1,] -0.5749566
#> 
#> $per_period$`1`$difficulty
#> [1] -10.47267
#> 
#> $per_period$`1`$n_votes_in_period
#> [1] 1
#> 
#> 
#> $per_period$`2`
#> $per_period$`2`$period
#> [1] 2
#> 
#> $per_period$`2`$ideal_points
#>             [,1]
#> [1,]  0.58716913
#> [2,] -0.36851679
#> [3,]  0.08946095
#> [4,]  0.22264344
#> 
#> $per_period$`2`$discrimination
#>            [,1]
#> [1,] -0.5749566
#> 
#> $per_period$`2`$difficulty
#> [1] -10.47267
#> 
#> $per_period$`2`$n_votes_in_period
#> [1] 1
#> 
#> 
#> $per_period$`3`
#> $per_period$`3`$period
#> [1] 3
#> 
#> $per_period$`3`$ideal_points
#>             [,1]
#> [1,]  0.58716913
#> [2,] -0.36851679
#> [3,]  0.08946095
#> [4,]  0.22264344
#> 
#> $per_period$`3`$discrimination
#>            [,1]
#> [1,] -0.5749566
#> 
#> $per_period$`3`$difficulty
#> [1] -10.47267
#> 
#> $per_period$`3`$n_votes_in_period
#> [1] 1
#> 
#> 
#> $per_period$`4`
#> $per_period$`4`$period
#> [1] 4
#> 
#> $per_period$`4`$ideal_points
#>             [,1]
#> [1,]  0.58716913
#> [2,] -0.36851679
#> [3,]  0.08946095
#> [4,]  0.22264344
#> 
#> $per_period$`4`$discrimination
#>            [,1]
#> [1,] -0.5749566
#> 
#> $per_period$`4`$difficulty
#> [1] -10.47267
#> 
#> $per_period$`4`$n_votes_in_period
#> [1] 1
#> 
#> 
#> 
#> $periods
#> [1] 1 2 3 4
#> 
#> $n_periods
#> [1] 4
#> 
#> $n_legislators
#> [1] 4
#> 
#> $n_samples_target
#> [1] 500
#> 
#> $burn_in_target
#> [1] 100
#> 
#> $engine
#> [1] "morie_spatial_voting_em_irt per-period (deterministic EM approximation; full Martin-Quinn dynamic-IRT with Brownian-motion smoothing not yet ported -- see Martin & Quinn 2002)"
#>