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lines 5-104 of file: xrst/table/prior_sim_table.xrst
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{xrst_begin prior_sim_table}

Simulated Variation in Prior
############################

Discussion
**********
The ``prior_sim`` table is created during a
:ref:`simulate_command-name` .
It contains :ref:`simulate_command@number_simulate`
sets of priors where each set
has one row for each variable in the :ref:`var_table-name` .
Each row has a value, age difference, and time difference prior.

prior_sim_id
************
This column has type ``integer`` and is the primary key for this table.
Its initial value is zero, and it increments by one for each row.

simulate_index
**************
The column has type ``integer`` . It specifies the index
for this simulated prior value. This index starts at zero,
repeats as the same for the entire set of *var_id* values,
and then increments by one between prior sets.
The final (maximum) value for *simulate_index* is
:ref:`simulate_command@number_simulate` minus one.

var_id
******
This column has type ``integer`` and is the primary key
for the :ref:`var_table-name` .
This identifies which :ref:`var_table@var_id`
each row of the prior_sim table corresponds to.
If *n_var* is the number of rows in the var table,

    *prior_sim_id* = *simulate_index* * *n_var* + *var_id*

for *simulate_index* equal zero to *number_simulate* ``-1``
and *var_id* equal zero to ``n_var`` *-1* .

prior_sim_value
***************
This column has type ``real`` and is
a simulated from the value prior for this variable.
If there is no value prior, or if the density for the value prior
is uniform, *prior_sim_value* is ``null`` .

zero_sum_child_rate
===================
If the :ref:`option_table@Zero Sum Constraints@zero_sum_child_rate` option
is chosen for a rate, the simulated values for the corresponding
:ref:`model_variables@Random Effects, u@Child Rate Effects`
will sum to zero at each grid point in the corresponding smoothing for;
see :ref:`rate_table@child_smooth_id` in the rate table.
Note that using ``zero_sum_child_rate`` for a rate
requires that the same smoothing is used by all the child random effects
for that rate.
This is done by simulating using independent priors and then subtracting
averages of the simulated values.

zero_sum_mulcov_group
=====================
If the :ref:`option_table@Zero Sum Constraints@zero_sum_mulcov_group` option
is chosen for a group, the simulated values for the corresponding
:ref:`model_variables@Random Effects, u@Subgroup Covariate Multipliers`
will sum to zero at each grid point in the corresponding smoothing.
This summation is with respect to subgroups in the group specified
by a :ref:`mulcov_table@group_id` in the mulcov table.

prior_sim_dage
**************
This column has type ``real`` and is
a simulated from the dage prior for this variable.
If there is no dage prior, or if the density for the dage prior
is uniform, *prior_sim_dage* is ``null`` .

prior_sim_dtime
***************
This column has type ``real`` and is
a simulated from the dtime prior for this variable.
If there is no dtime prior, or if the density for the dtime prior
is uniform, *prior_sim_dtime* is ``null`` .

Censoring
*********
If the simulated values for the prior is censored to be within the
upper and lower limits for the corresponding variable.
To be specific, if *sim* is the value simulated just using the
:ref:`prior_table@density_id` ,
and *lower* , *upper* are the corresponding limits;
the corresponding simulated value or difference is

    ``max`` [ *upper* , ``min`` ( *lower* , *sim*  ) ]

Example
*******
See the :ref:`simulate_command.py-name` example and test.

{xrst_end prior_sim_table}