31  Bayesian Mortality Modeling

Author

Alec Loudenback

“After a year of intense mental struggle, however, [Arthur Bailey] realized to his consternation that actuarial sledgehammering worked. He even preferred [the Bayesian underpinnings of credibility theory] to the elegance of frequentism. He positively liked formulae that described ‘actual data. . . . I realized that the hard-shelled underwriters were recognizing certain facts of life neglected by the statistical theorists.’ He wanted to give more weight to a large volume of data than to the frequentists’ small sample; doing so felt surprisingly ‘logical and reasonable.’ He concluded that only a ‘suicidal’ actuary would use Fisher’s method of maximum likelihood, which assigned a zero probability to nonevents.” - Sharon Bertsch McGrayne, Excerpt From The Theory That Would Not Die

31.1 Chapter Overview

An example of using a Bayesian MCMC approach to fitting a mortality curve to sample data, with multi-level models and censored data.

31.2 Generating fake data

The problem of interest is to look at mortality rates, which are given in terms of exposures (whether or not a life experienced a death in a given year).

We’ll grab some example rates from an insurance table, which has a “selection” component: When someone enters observation, say at age 50, their mortality is path dependent (so for someone who started being observed at 50 will have a different risk/mortality rate at age 55 than someone who started being observed at 45).

Addtionally, there may be additional groups of interest, such as:

  • high/medium/low risk classification
  • sex
  • group (e.g. company, data source, etc.)
  • type of insurance product offered

The example data will start with only the risk classification above.

using MortalityTables
using Turing
using DataFramesMeta
using MCMCChains
using LinearAlgebra
using CairoMakie
using StatsBase
n = 10_000
inforce = map(1:n) do i
    (
        issue_age=rand(30:70),
        risk_level=rand(1:3),
    )

end
10000-element Vector{@NamedTuple{issue_age::Int64, risk_level::Int64}}:
 (issue_age = 31, risk_level = 3)
 (issue_age = 68, risk_level = 1)
 (issue_age = 39, risk_level = 2)
 (issue_age = 37, risk_level = 3)
 (issue_age = 53, risk_level = 2)
 (issue_age = 30, risk_level = 2)
 (issue_age = 33, risk_level = 2)
 (issue_age = 70, risk_level = 1)
 (issue_age = 39, risk_level = 1)
 (issue_age = 44, risk_level = 2)
 ⋮
 (issue_age = 45, risk_level = 1)
 (issue_age = 67, risk_level = 2)
 (issue_age = 65, risk_level = 2)
 (issue_age = 53, risk_level = 1)
 (issue_age = 41, risk_level = 3)
 (issue_age = 57, risk_level = 2)
 (issue_age = 46, risk_level = 1)
 (issue_age = 60, risk_level = 1)
 (issue_age = 53, risk_level = 1)
base_table = MortalityTables.table("2001 VBT Residual Standard Select and Ultimate - Male Nonsmoker, ANB")

function tabular_mortality(params, issue_age, att_age, risk_level)
    q = params.ultimate[att_age]
    if risk_level == 1
        q *= 0.7
    elseif risk_level == 2
        q = q
    else
        q *= 1.5
    end
end
tabular_mortality (generic function with 1 method)
function model_outcomes(inforce, assumption, assumption_params; n_years=5)

    outcomes = map(inforce) do pol
        alive = 1
        sim = map(1:n_years) do t
            att_age = pol.issue_age + t - 1
            q = assumption(
                assumption_params,
                pol.issue_age,
                att_age,
                pol.risk_level
            )
            if rand() < q
                out = (att_age=att_age, exposures=alive, death=1)
                alive = 0
                out
            else
                (att_age=att_age, exposures=alive, death=0)
            end
        end
        filter!(x -> x.exposures == 1, sim)

    end


    df = DataFrame(inforce)

    df.outcomes = outcomes
    df = flatten(df, :outcomes)

    df.att_age = [x.att_age for x in df.outcomes]
    df.death = [x.death for x in df.outcomes]
    df.exposures = [x.exposures for x in df.outcomes]
    select!(df, Not(:outcomes))


end

exposures = model_outcomes(inforce, tabular_mortality, base_table)
data = combine(groupby(exposures, [:issue_age, :att_age])) do subdf
    (exposures=nrow(subdf),
        deaths=sum(subdf.death),
        fraction=sum(subdf.death) / nrow(subdf))
end


data2 = combine(groupby(exposures, [:issue_age, :att_age, :risk_level])) do subdf
    (exposures=nrow(subdf),
        deaths=sum(subdf.death),
        fraction=sum(subdf.death) / nrow(subdf))
end
615×6 DataFrame
590 rows omitted
Row issue_age att_age risk_level exposures deaths fraction
Int64 Int64 Int64 Int64 Int64 Float64
1 30 30 1 75 0 0.0
2 30 30 2 82 0 0.0
3 30 30 3 76 0 0.0
4 30 31 1 75 0 0.0
5 30 31 2 82 0 0.0
6 30 31 3 76 0 0.0
7 30 32 1 75 0 0.0
8 30 32 2 82 0 0.0
9 30 32 3 76 0 0.0
10 30 33 1 75 0 0.0
11 30 33 2 82 0 0.0
12 30 33 3 76 0 0.0
13 30 34 1 75 0 0.0
604 70 71 1 103 1 0.00970874
605 70 71 2 83 5 0.060241
606 70 71 3 86 3 0.0348837
607 70 72 1 102 3 0.0294118
608 70 72 2 78 2 0.025641
609 70 72 3 83 5 0.060241
610 70 73 1 99 3 0.030303
611 70 73 2 76 1 0.0131579
612 70 73 3 78 4 0.0512821
613 70 74 1 96 2 0.0208333
614 70 74 2 75 3 0.04
615 70 74 3 74 5 0.0675676

31.3 1: A single binomial parameter model

Estimate \(q\), the average mortality rate, not accounting for any variation within the population/sample. Our model is defines as:

\[ q ~ Beta(1,1) p(\text{death}) ~ \text{Binomial}(q) \]

@model function mortality(data, deaths)
    q ~ Beta(1, 1)
    for i = 1:nrow(data)
        deaths[i] ~ Binomial(data.exposures[i], q)
    end
end

m1 = mortality(data, data.deaths)
DynamicPPL.Model{typeof(mortality), (:data, :deaths), (), (), Tuple{DataFrame, Vector{Int64}}, Tuple{}, DynamicPPL.DefaultContext}(mortality, (data = 205×5 DataFrame
 Row  issue_age  att_age  exposures  deaths  fraction    Int64      Int64    Int64      Int64   Float64    
─────┼───────────────────────────────────────────────────
   1 │        30       30        233       0  0.0
   2 │        30       31        233       0  0.0
   3 │        30       32        233       0  0.0
   4 │        30       33        233       0  0.0
   5 │        30       34        233       0  0.0
   6 │        31       31        218       1  0.00458716
   7 │        31       32        217       0  0.0
   8 │        31       33        217       0  0.0
  ⋮  │     ⋮         ⋮         ⋮        ⋮         ⋮
 199 │        69       72        247       9  0.0364372
 200 │        69       73        238      10  0.0420168
 201 │        70       70        279       7  0.0250896
 202 │        70       71        272       9  0.0330882
 203 │        70       72        263      10  0.0380228
 204 │        70       73        253       8  0.0316206
 205 │        70       74        245      10  0.0408163
                                         190 rows omitted, deaths = [0, 0, 0, 0, 0, 1, 0, 0, 2, 0  …  4, 8, 6, 9, 10, 7, 9, 10, 8, 10]), NamedTuple(), DynamicPPL.DefaultContext())

31.3.1 Sampling from the posterior

We use a No-U-Turn-Sampler (NUTS) technique to sample multiple chains at once:

num_chains = 4
chain = sample(m1, NUTS(), MCMCThreads(), 400, num_chains)
Chains MCMC chain (400×13×4 Array{Float64, 3}):

Iterations        = 201:1:600
Number of chains  = 4
Samples per chain = 400
Wall duration     = 2.08 seconds
Compute duration  = 8.21 seconds
parameters        = q
internals         = lp, n_steps, is_accept, acceptance_rate, log_density, hamiltonian_energy, hamiltonian_energy_error, max_hamiltonian_energy_error, tree_depth, numerical_error, step_size, nom_step_size

Summary Statistics
  parameters      mean       std      mcse   ess_bulk   ess_tail      rhat   e     Symbol   Float64   Float64   Float64    Float64    Float64   Float64     ⋯

           q    0.0087    0.0004    0.0000   739.2302   984.6658    1.0036     ⋯
                                                                1 column omitted

Quantiles
  parameters      2.5%     25.0%     50.0%     75.0%     97.5% 
      Symbol   Float64   Float64   Float64   Float64   Float64 

           q    0.0079    0.0084    0.0087    0.0090    0.0095

Here, we have asked for the outcomes to be modeled via a single parameter for the population. We see that the posterior distribution of \(q\) is very close to the overall population mortality rate:

# Posterior mean of q should be close to the pooled fraction
sum(data.deaths) / sum(data.exposures)
0.008680449675753694

However, We can see that the sampling of possible posterior parameters doesn’t really fit the data very well since our model was so simplified. The lines represent the posterior binomial probability.

This is saying that for the observed data, if there really is just a single probability p that governs the true process that came up with the data, there’s a pretty narrow range of values it could possibly be:

let
    data_weight = sqrt.(data.exposures) / 2
    f = Figure(title="Parametric Bayesian Mortality"
    )
    ax = Axis(f[1, 1],
        xlabel="age",
        ylabel="mortality rate",
        limits=(nothing, nothing, -0.01, 0.10),
    )
    scatter!(ax,
        data.att_age,
        data.fraction,
        markersize=data_weight,
        color=(:blue, 0.5),
        label="Experience data point (size indicates relative exposure quantity)",)

    # show n samples from the posterior plotted on the graph
    n = 300
    ages = sort!(unique(data.att_age))

    q_posterior = sample(chain, n)[:q]


    for i in 1:n

        hlines!(ax, [q_posterior[i]], color=(:grey, 0.1))
    end

    sim05 = Float64[]
    sim95 = Float64[]
    for r in eachrow(data)
        outcomes = map(1:n) do i
            rand(Binomial(r.exposures, q_posterior[i]), 500)
        end
        push!(sim05, quantile(Iterators.flatten(outcomes), 0.05) / r.exposures)
        push!(sim95, quantile(Iterators.flatten(outcomes), 0.95) / r.exposures)


    end



    f
end
let
    n = 300
    q_posterior = sample(chain, n)[:q]


end
2-dimensional AxisArray{Float64,2,...} with axes:
    :iter, 1:300
    :chain, 1:1
And data, a 300×1 Matrix{Float64}:
 0.008619788009461815
 0.008501715283944257
 0.00863829916911474
 0.008534309043623008
 0.008548886636930566
 0.009015823843725004
 0.008631078079973296
 0.008959770158964118
 0.008581889416265311
 0.008166368819955657
 ⋮
 0.008745406235479064
 0.008363059920630897
 0.008036400737086091
 0.008804744442405244
 0.008939660609940472
 0.008725058484678791
 0.008599700311582394
 0.008158724288367893
 0.008700386033144165

31.4 2. Parametric model

In this example, we utilize a MakehamBeard parameterization because it’s already very similar in form to a logistic function. This is important because our desired output is a probability (ie the probability of a death at a given age), so the value must be constrained to be in the interval between zero and one.

The prior values for a,b,c, and k are chosen to constrain the hazard (mortality) rate to be between zero and one.

This isn’t an ideal parameterization (e.g. we aren’t including information about the select underwriting period), but is an example of utilizing Bayesian techniques on life experience data. ”

@model function mortality2(data, deaths)
    a ~ Exponential(0.1)
    b ~ Exponential(0.1)
    c = 0.0
    k ~ truncated(Exponential(1), 1, Inf)

    # use the variables to create a parametric mortality model
    m = MortalityTables.MakehamBeard(; a, b, c, k)

    # loop through the rows of the dataframe to let Turing observe the data 
    # and how consistent the parameters are with the data
    for i = 1:nrow(data)
        age = data.att_age[i]
        q = MortalityTables.hazard(m, age)
        deaths[i] ~ Binomial(data.exposures[i], q)
    end
end
mortality2 (generic function with 2 methods)

We combine the model with the data and sample from the posterior using a similar call as before:

m2 = mortality2(data, data.deaths)

chain2 = sample(m2, NUTS(), MCMCThreads(), 400, num_chains)
Chains MCMC chain (400×15×4 Array{Float64, 3}):

Iterations        = 201:1:600
Number of chains  = 4
Samples per chain = 400
Wall duration     = 5.9 seconds
Compute duration  = 22.22 seconds
parameters        = a, b, k
internals         = lp, n_steps, is_accept, acceptance_rate, log_density, hamiltonian_energy, hamiltonian_energy_error, max_hamiltonian_energy_error, tree_depth, numerical_error, step_size, nom_step_size

Summary Statistics
  parameters      mean       std      mcse   ess_bulk   ess_tail      rhat   e     Symbol   Float64   Float64   Float64    Float64    Float64   Float64     ⋯

           a    0.0001    0.0000    0.0000   584.7235   672.9357    1.0042     ⋯
           b    0.0874    0.0054    0.0002   581.3264   681.4963    1.0045     ⋯
           k    1.9436    0.8760    0.0288   656.5508   499.7290    1.0011     ⋯
                                                                1 column omitted

Quantiles
  parameters      2.5%     25.0%     50.0%     75.0%     97.5% 
      Symbol   Float64   Float64   Float64   Float64   Float64 

           a    0.0000    0.0000    0.0001    0.0001    0.0001
           b    0.0774    0.0837    0.0873    0.0910    0.0986
           k    1.0311    1.2973    1.6984    2.3343    4.2571

31.4.1 Plotting samples from the posterior

We can see that the sampling of possible posterior parameters fits the data well:

let
    data_weight = sqrt.(data.exposures) / 2

    p = scatter(
        data.att_age,
        data.fraction,
        markersize=data_weight,
        alpha=0.5,
        label="Experience data point (size indicates relative exposure quantity)",
        axis=(
            xlabel="age",
            limits=(nothing, nothing, -0.01, 0.10),
            ylabel="mortality rate",
            title="Parametric Bayesian Mortality"
        )
    )


    # show n samples from the posterior plotted on the graph
    n = 300
    ages = sort!(unique(data.att_age))

    for i in 1:n
        s = sample(chain2, 1)
        a = only(s[:a])
        b = only(s[:b])
        k = only(s[:k])
        c = 0
        m = MortalityTables.MakehamBeard(; a, b, c, k)
        lines!(ages, age -> MortalityTables.hazard(m, age), alpha=0.1, label="")
    end
    p
end
let
    data_weight = sqrt.(data.exposures) / 2
    f = Figure(title="Parametric Bayesian Mortality"
    )
    ax = Axis(f[1, 1],
        xlabel="age",
        ylabel="mortality rate",
        limits=(nothing, nothing, -0.01, 0.10),
    )
    scatter!(ax,
        data.att_age,
        data.fraction,
        markersize=data_weight,
        color=(:blue, 0.5),
        label="Experience data point (size indicates relative exposure quantity)",)

    # show n samples from the posterior plotted on the graph
    n = 300
    ages = sort!(unique(data.att_age))

    for i in 1:n
        s = sample(chain2, 1)
        a = only(s[:a])
        b = only(s[:b])
        k = only(s[:k])
        c = 0
        m = MortalityTables.MakehamBeard(; a, b, c, k)
        qs = MortalityTables.hazard.(m, ages)
        lines!(ax, ages, qs, color=(:grey, 0.1))
    end
    f
end

Recall that the lines are not plotting the possible outcomes of the claims rates, but the mean claims rate for the given age.

31.5 3. Multi-level model

This model extends the prior to create a multi-level model. Each risk class (risk_level) gets its own \(a\) paramater in the MakhamBeard model. The prior for \(a_i\) is determined by the hyper-parameter \(\bar{a}\).

@model function mortality3(data, deaths)
    risk_levels = length(levels(data.risk_level))
    b ~ Exponential(0.1)
    ā ~ Exponential(0.1)
    a ~ filldist(Exponential(ā), risk_levels)
    c = 0
    k ~ truncated(Exponential(1), 1, Inf)

    # use the variables to create a parametric mortality model

    # loop through the rows of the dataframe to let Turing observe the data 
    # and how consistent the parameters are with the data
    for i = 1:nrow(data)
        risk = data.risk_level[i]

        m = MortalityTables.MakehamBeard(; a=a[risk], b, c, k)
        age = data.att_age[i]
        q = MortalityTables.hazard(m, age)
        deaths[i] ~ Binomial(data.exposures[i], q)
    end
end

m3 = mortality3(data2, data2.deaths)

chain3 = sample(m3, NUTS(), 1000)

summarize(chain3)
  parameters      mean       std      mcse   ess_bulk   ess_tail      rhat   e     Symbol   Float64   Float64   Float64    Float64    Float64   Float64     ⋯

           b    0.0884    0.0056    0.0004   236.3095   352.3040    1.0079     ⋯
           ā    0.0002    0.0003    0.0000   306.6128   326.3798    1.0002     ⋯
        a[1]    0.0000    0.0000    0.0000   248.0581   352.1054    1.0084     ⋯
        a[2]    0.0001    0.0000    0.0000   241.2689   365.3431    1.0090     ⋯
        a[3]    0.0001    0.0000    0.0000   250.2072   346.8012    1.0068     ⋯
           k    2.0106    1.1428    0.0451   440.6973   254.5145    1.0044     ⋯
                                                                1 column omitted
let data = data2

    data_weight = sqrt.(data.exposures)
    color_i = data.risk_level
    cm = CairoMakie.Makie.wong_colors()

    p, ax, _ = scatter(
        data.att_age,
        data.fraction,
        markersize=data_weight,
        alpha=0.5,
        color=[(CairoMakie.Makie.wong_colors()[c], 0.7) for c in color_i],
        colormap=CairoMakie.Makie.wong_colors(),
        label="Experience data point (size indicates relative exposure quantity)",
        axis=(
            xlabel="age",
            limits=(nothing, nothing, -0.01, 0.10),
            ylabel="mortality rate",
            title="Parametric Bayesian Mortality"
        )
    )


    # show n samples from the posterior plotted on the graph
    n = 100

    ages = sort!(unique(data.att_age))
    for r in 1:3
        for i in 1:n
            s = sample(chain3, 1)
            a = only(s[Symbol("a[$r]")])
            b = only(s[:b])
            k = only(s[:k])
            c = 0
            m = MortalityTables.MakehamBeard(; a, b, c, k)
            lines!(ages, age -> MortalityTables.hazard(m, age), label="risk level $r", alpha=0.2, color=(CairoMakie.Makie.wong_colors()[r], 0.2))
        end
    end
    axislegend(ax, merge=true)
    p
end

Again, the lines are not plotting the possible outcomes of the claims rates, but the mean claims rate for the given age and risk class.

31.6 Handling non-unit exposures

The key is to use the Poisson distribution, which is a continuous approximation to the Binomial distribution:

@model function mortality4(data, deaths)
    risk_levels = length(levels(data.risk_level))
    b ~ Exponential(0.1)
    ā ~ Exponential(0.1)
    a ~ filldist(Exponential(ā), risk_levels)
    c ~ Beta(4, 18)
    k ~ truncated(Exponential(1), 1, Inf)

    # use the variables to create a parametric mortality model

    # loop through the rows of the dataframe to let Turing observe the data 
    # and how consistent the parameters are with the data
    for i = 1:nrow(data)
        risk = data.risk_level[i]

        m = MortalityTables.MakehamBeard(; a=a[risk], b, c, k)
        age = data.att_age[i]
        q = MortalityTables.hazard(m, age)
        deaths[i] ~ Poisson(data.exposures[i] * q)
    end
end

m4 = mortality4(data2, data2.deaths)

chain4 = sample(m4, NUTS(), 1000)
Chains MCMC chain (1000×19×1 Array{Float64, 3}):

Iterations        = 501:1:1500
Number of chains  = 1
Samples per chain = 1000
Wall duration     = 27.11 seconds
Compute duration  = 27.11 seconds
parameters        = b, ā, a[1], a[2], a[3], c, k
internals         = lp, n_steps, is_accept, acceptance_rate, log_density, hamiltonian_energy, hamiltonian_energy_error, max_hamiltonian_energy_error, tree_depth, numerical_error, step_size, nom_step_size

Summary Statistics
  parameters      mean       std      mcse   ess_bulk   ess_tail      rhat   e     Symbol   Float64   Float64   Float64    Float64    Float64   Float64     ⋯

           b    0.1032    0.0087    0.0007   162.3063   194.7900    1.0339     ⋯
           ā    0.0001    0.0001    0.0000   211.9405   286.5972    1.0300     ⋯
        a[1]    0.0000    0.0000    0.0000   162.8706   172.3253    1.0326     ⋯
        a[2]    0.0000    0.0000    0.0000   150.3623   222.1351    1.0341     ⋯
        a[3]    0.0000    0.0000    0.0000   156.1219   135.7489    1.0368     ⋯
           c    0.0011    0.0004    0.0000   243.3639   499.4269    1.0118     ⋯
           k    2.0483    1.0739    0.0432   364.4628   237.0317    1.0007     ⋯
                                                                1 column omitted

Quantiles
  parameters      2.5%     25.0%     50.0%     75.0%     97.5% 
      Symbol   Float64   Float64   Float64   Float64   Float64 

           b    0.0875    0.0968    0.1027    0.1090    0.1211
           ā    0.0000    0.0000    0.0000    0.0001    0.0004
        a[1]    0.0000    0.0000    0.0000    0.0000    0.0000
        a[2]    0.0000    0.0000    0.0000    0.0000    0.0000
        a[3]    0.0000    0.0000    0.0000    0.0000    0.0001
           c    0.0004    0.0008    0.0010    0.0013    0.0019
           k    1.0197    1.3139    1.7338    2.4389    4.6872
risk_factors4 = [mean(chain4[Symbol("a[$f]")]) for f in 1:3]

risk_factors4 ./ risk_factors4[2]

let data = data2

    data_weight = sqrt.(data.exposures) / 2
    color_i = data.risk_level

    p, ax, _ = scatter(
        data.att_age,
        data.fraction,
        markersize=data_weight,
        alpha=0.5,
        color=color_i,
        label="Experience data point (size indicates relative exposure quantity)",
        axis=(xlabel="age",
            limits=(nothing, nothing, -0.01, 0.10),
            ylabel="mortality rate",
            title="Parametric Bayesian Mortality"
        )
    )


    # show n samples from the posterior plotted on the graph
    n = 100

    ages = sort!(unique(data.att_age))
    for r in 1:3
        for i in 1:n
            s = sample(chain4, 1)
            a = only(s[Symbol("a[$r]")])
            b = only(s[:b])
            k = only(s[:k])
            c = 0
            m = MortalityTables.MakehamBeard(; a, b, c, k)
            lines!(ages, age -> MortalityTables.hazard(m, age), label="risk level $r", alpha=0.2, color=(CairoMakie.Makie.wong_colors()[r], 0.2))
        end
    end
    axislegend(ax, merge=true)
    p
end

31.7 Model Predictions

We can generate predictive estimates by passing a vector of missing in place of the outcome variables and then calling predict.

We get a table of values where each row is the the prediction implied by the corresponding chain sample, and the columns are the predicted value for each of the outcomes in our original dataset.

preds = predict(mortality4(data2, fill(missing, length(data2.deaths))), chain4)
Chains MCMC chain (1000×615×1 Array{Float64, 3}):

Iterations        = 1:1:1000
Number of chains  = 1
Samples per chain = 1000
parameters        = deaths[1], deaths[2], deaths[3], deaths[4], deaths[5], deaths[6], deaths[7], deaths[8], deaths[9], deaths[10], deaths[11], deaths[12], deaths[13], deaths[14], deaths[15], deaths[16], deaths[17], deaths[18], deaths[19], deaths[20], deaths[21], deaths[22], deaths[23], deaths[24], deaths[25], deaths[26], deaths[27], deaths[28], deaths[29], deaths[30], deaths[31], deaths[32], deaths[33], deaths[34], deaths[35], deaths[36], deaths[37], deaths[38], deaths[39], deaths[40], deaths[41], deaths[42], deaths[43], deaths[44], deaths[45], deaths[46], deaths[47], deaths[48], deaths[49], deaths[50], deaths[51], deaths[52], deaths[53], deaths[54], deaths[55], deaths[56], deaths[57], deaths[58], deaths[59], deaths[60], deaths[61], deaths[62], deaths[63], deaths[64], deaths[65], deaths[66], deaths[67], deaths[68], deaths[69], deaths[70], deaths[71], deaths[72], deaths[73], deaths[74], deaths[75], deaths[76], deaths[77], deaths[78], deaths[79], deaths[80], deaths[81], deaths[82], deaths[83], deaths[84], deaths[85], deaths[86], deaths[87], deaths[88], deaths[89], deaths[90], deaths[91], deaths[92], deaths[93], deaths[94], deaths[95], deaths[96], deaths[97], deaths[98], deaths[99], deaths[100], deaths[101], deaths[102], deaths[103], deaths[104], deaths[105], deaths[106], deaths[107], deaths[108], deaths[109], deaths[110], deaths[111], deaths[112], deaths[113], deaths[114], deaths[115], deaths[116], deaths[117], deaths[118], deaths[119], deaths[120], deaths[121], deaths[122], deaths[123], deaths[124], deaths[125], deaths[126], deaths[127], deaths[128], deaths[129], deaths[130], deaths[131], deaths[132], deaths[133], deaths[134], deaths[135], deaths[136], deaths[137], deaths[138], deaths[139], deaths[140], deaths[141], deaths[142], deaths[143], deaths[144], deaths[145], deaths[146], deaths[147], deaths[148], deaths[149], deaths[150], deaths[151], deaths[152], deaths[153], deaths[154], deaths[155], deaths[156], deaths[157], deaths[158], deaths[159], deaths[160], deaths[161], deaths[162], deaths[163], deaths[164], deaths[165], deaths[166], deaths[167], deaths[168], deaths[169], deaths[170], deaths[171], deaths[172], deaths[173], deaths[174], deaths[175], deaths[176], deaths[177], deaths[178], deaths[179], deaths[180], deaths[181], deaths[182], deaths[183], deaths[184], deaths[185], deaths[186], deaths[187], deaths[188], deaths[189], deaths[190], deaths[191], deaths[192], deaths[193], deaths[194], deaths[195], deaths[196], deaths[197], deaths[198], deaths[199], deaths[200], deaths[201], deaths[202], deaths[203], deaths[204], deaths[205], deaths[206], deaths[207], deaths[208], deaths[209], deaths[210], deaths[211], deaths[212], deaths[213], deaths[214], deaths[215], deaths[216], deaths[217], deaths[218], deaths[219], deaths[220], deaths[221], deaths[222], deaths[223], deaths[224], deaths[225], deaths[226], deaths[227], deaths[228], deaths[229], deaths[230], deaths[231], deaths[232], deaths[233], deaths[234], deaths[235], deaths[236], deaths[237], deaths[238], deaths[239], deaths[240], deaths[241], deaths[242], deaths[243], deaths[244], deaths[245], deaths[246], deaths[247], deaths[248], deaths[249], deaths[250], deaths[251], deaths[252], deaths[253], deaths[254], deaths[255], deaths[256], deaths[257], deaths[258], deaths[259], deaths[260], deaths[261], deaths[262], deaths[263], deaths[264], deaths[265], deaths[266], deaths[267], deaths[268], deaths[269], deaths[270], deaths[271], deaths[272], deaths[273], deaths[274], deaths[275], deaths[276], deaths[277], deaths[278], deaths[279], deaths[280], deaths[281], deaths[282], deaths[283], deaths[284], deaths[285], deaths[286], deaths[287], deaths[288], deaths[289], deaths[290], deaths[291], deaths[292], deaths[293], deaths[294], deaths[295], deaths[296], deaths[297], deaths[298], deaths[299], deaths[300], deaths[301], deaths[302], deaths[303], deaths[304], deaths[305], deaths[306], deaths[307], deaths[308], deaths[309], deaths[310], deaths[311], deaths[312], deaths[313], deaths[314], deaths[315], deaths[316], deaths[317], deaths[318], deaths[319], deaths[320], deaths[321], deaths[322], deaths[323], deaths[324], deaths[325], deaths[326], deaths[327], deaths[328], deaths[329], deaths[330], deaths[331], deaths[332], deaths[333], deaths[334], deaths[335], deaths[336], deaths[337], deaths[338], deaths[339], deaths[340], deaths[341], deaths[342], deaths[343], deaths[344], deaths[345], deaths[346], deaths[347], deaths[348], deaths[349], deaths[350], deaths[351], deaths[352], deaths[353], deaths[354], deaths[355], deaths[356], deaths[357], deaths[358], deaths[359], deaths[360], deaths[361], deaths[362], deaths[363], deaths[364], deaths[365], deaths[366], deaths[367], deaths[368], deaths[369], deaths[370], deaths[371], deaths[372], deaths[373], deaths[374], deaths[375], deaths[376], deaths[377], deaths[378], deaths[379], deaths[380], deaths[381], deaths[382], deaths[383], deaths[384], deaths[385], deaths[386], deaths[387], deaths[388], deaths[389], deaths[390], deaths[391], deaths[392], deaths[393], deaths[394], deaths[395], deaths[396], deaths[397], deaths[398], deaths[399], deaths[400], deaths[401], deaths[402], deaths[403], deaths[404], deaths[405], deaths[406], deaths[407], deaths[408], deaths[409], deaths[410], deaths[411], deaths[412], deaths[413], deaths[414], deaths[415], deaths[416], deaths[417], deaths[418], deaths[419], deaths[420], deaths[421], deaths[422], deaths[423], deaths[424], deaths[425], deaths[426], deaths[427], deaths[428], deaths[429], deaths[430], deaths[431], deaths[432], deaths[433], deaths[434], deaths[435], deaths[436], deaths[437], deaths[438], deaths[439], deaths[440], deaths[441], deaths[442], deaths[443], deaths[444], deaths[445], deaths[446], deaths[447], deaths[448], deaths[449], deaths[450], deaths[451], deaths[452], deaths[453], deaths[454], deaths[455], deaths[456], deaths[457], deaths[458], deaths[459], deaths[460], deaths[461], deaths[462], deaths[463], deaths[464], deaths[465], deaths[466], deaths[467], deaths[468], deaths[469], deaths[470], deaths[471], deaths[472], deaths[473], deaths[474], deaths[475], deaths[476], deaths[477], deaths[478], deaths[479], deaths[480], deaths[481], deaths[482], deaths[483], deaths[484], deaths[485], deaths[486], deaths[487], deaths[488], deaths[489], deaths[490], deaths[491], deaths[492], deaths[493], deaths[494], deaths[495], deaths[496], deaths[497], deaths[498], deaths[499], deaths[500], deaths[501], deaths[502], deaths[503], deaths[504], deaths[505], deaths[506], deaths[507], deaths[508], deaths[509], deaths[510], deaths[511], deaths[512], deaths[513], deaths[514], deaths[515], deaths[516], deaths[517], deaths[518], deaths[519], deaths[520], deaths[521], deaths[522], deaths[523], deaths[524], deaths[525], deaths[526], deaths[527], deaths[528], deaths[529], deaths[530], deaths[531], deaths[532], deaths[533], deaths[534], deaths[535], deaths[536], deaths[537], deaths[538], deaths[539], deaths[540], deaths[541], deaths[542], deaths[543], deaths[544], deaths[545], deaths[546], deaths[547], deaths[548], deaths[549], deaths[550], deaths[551], deaths[552], deaths[553], deaths[554], deaths[555], deaths[556], deaths[557], deaths[558], deaths[559], deaths[560], deaths[561], deaths[562], deaths[563], deaths[564], deaths[565], deaths[566], deaths[567], deaths[568], deaths[569], deaths[570], deaths[571], deaths[572], deaths[573], deaths[574], deaths[575], deaths[576], deaths[577], deaths[578], deaths[579], deaths[580], deaths[581], deaths[582], deaths[583], deaths[584], deaths[585], deaths[586], deaths[587], deaths[588], deaths[589], deaths[590], deaths[591], deaths[592], deaths[593], deaths[594], deaths[595], deaths[596], deaths[597], deaths[598], deaths[599], deaths[600], deaths[601], deaths[602], deaths[603], deaths[604], deaths[605], deaths[606], deaths[607], deaths[608], deaths[609], deaths[610], deaths[611], deaths[612], deaths[613], deaths[614], deaths[615]
internals         = 

Summary Statistics
  parameters      mean       std      mcse    ess_bulk    ess_tail      rhat      Symbol   Float64   Float64   Float64     Float64     Float64   Float64   ⋯

   deaths[1]    0.0860    0.2978    0.0090   1082.3866   1010.5515    1.0004   ⋯
   deaths[2]    0.1370    0.3747    0.0122    942.2927    941.8609    0.9991   ⋯
   deaths[3]    0.1360    0.3487    0.0112    971.8526   1004.0241    0.9998   ⋯
   deaths[4]    0.0960    0.3080    0.0097   1021.0017    682.2254    1.0001   ⋯
   deaths[5]    0.1250    0.3457    0.0115    907.9073    892.3067    0.9994   ⋯
   deaths[6]    0.1310    0.3660    0.0121    920.3683    933.4012    1.0041   ⋯
   deaths[7]    0.0990    0.3087    0.0111    761.7172    790.5959    0.9990   ⋯
   deaths[8]    0.1380    0.3675    0.0117    983.3500    952.1043    1.0001   ⋯
   deaths[9]    0.1410    0.3785    0.0117   1045.1133   1025.2438    0.9990   ⋯
  deaths[10]    0.0960    0.3208    0.0110    841.1203    831.2332    0.9996   ⋯
  deaths[11]    0.1370    0.3555    0.0118    909.0094    919.7658    1.0034   ⋯
  deaths[12]    0.1190    0.3507    0.0112    987.3264    990.3357    0.9999   ⋯
  deaths[13]    0.1170    0.3397    0.0109    946.5897    907.6851    1.0007   ⋯
  deaths[14]    0.1340    0.3823    0.0117   1079.0924    835.7793    1.0031   ⋯
  deaths[15]    0.1520    0.3963    0.0124   1031.8385    948.5814    0.9998   ⋯
  deaths[16]    0.0810    0.2802    0.0083   1137.7476   1008.0890    0.9991   ⋯
  deaths[17]    0.1310    0.3577    0.0122    837.0730    849.3045    1.0001   ⋯
      ⋮           ⋮         ⋮         ⋮          ⋮           ⋮          ⋮      ⋱
                                                   1 column and 598 rows omitted

Quantiles
  parameters      2.5%     25.0%     50.0%     75.0%     97.5% 
      Symbol   Float64   Float64   Float64   Float64   Float64 

   deaths[1]    0.0000    0.0000    0.0000    0.0000    1.0000
   deaths[2]    0.0000    0.0000    0.0000    0.0000    1.0000
   deaths[3]    0.0000    0.0000    0.0000    0.0000    1.0000
   deaths[4]    0.0000    0.0000    0.0000    0.0000    1.0000
   deaths[5]    0.0000    0.0000    0.0000    0.0000    1.0000
   deaths[6]    0.0000    0.0000    0.0000    0.0000    1.0000
   deaths[7]    0.0000    0.0000    0.0000    0.0000    1.0000
   deaths[8]    0.0000    0.0000    0.0000    0.0000    1.0000
   deaths[9]    0.0000    0.0000    0.0000    0.0000    1.0000
  deaths[10]    0.0000    0.0000    0.0000    0.0000    1.0000
  deaths[11]    0.0000    0.0000    0.0000    0.0000    1.0000
  deaths[12]    0.0000    0.0000    0.0000    0.0000    1.0000
  deaths[13]    0.0000    0.0000    0.0000    0.0000    1.0000
  deaths[14]    0.0000    0.0000    0.0000    0.0000    1.0000
  deaths[15]    0.0000    0.0000    0.0000    0.0000    1.0000
  deaths[16]    0.0000    0.0000    0.0000    0.0000    1.0000
  deaths[17]    0.0000    0.0000    0.0000    0.0000    1.0000
      ⋮           ⋮         ⋮         ⋮         ⋮         ⋮
                                                598 rows omitted