The Data Space

Input data shared by every by-policy projection.

The three input CSVs are read here, once per model, and referenced from Projection as data. Projection is parameterized by point_id, so each Projection[N] is a separate ItemSpace with its own cells cache; if the readers lived there, every model point would re-read every file. Holding them in an unparameterized Space reads each file once no matter how many policies are projected.

Inputs are external files: plain CSVs in the model folder’s parent directory, products/unit_linked_bond/, rather than data stored inside the model. The model folder therefore holds nothing but formulas — no _data/, no IOSpec, no embedded values — so a diff of the model shows logic changes only. This follows annuallife.TradLife_A; contrast basiclife.BasicTerm_S, which keeps its inputs inside the model through modelx’s IOSpec machinery.

The consequence worth knowing: the model is not portable on its own. Copying the ULB_UK_S folder without its parent’s CSVs produces a model that reads and then fails on first evaluation.

input_dir() resolves the directory from _model.path.parent at run time, so the model works wherever the repository is checked out. Each table has a filename Reference and a reader Cells:

Reference	Cells	File
model_point_file	model_point_table()	model_point_table.csv
mort_table_file	mort_table()	mort_table.csv
surr_table_file	surr_table()	surr_table.csv

Note what is not an input file. The charge rates — the annual management charge, the fund-borne further costs, the tax provision rate, the death-benefit uplift — are model point columns rather than a rate table, because they are per-policy contractual and discretionary parameters rather than experience assumptions, and because per-fund charge rate cards are not published anyway. The fund return is a single Reference on Projection, because the base run is deterministic.

Cells Descriptions

input_dir()

The directory holding the input CSVs: the model folder’s parent.

Inputs are external files, not data stored inside the model, so the model folder is pure formulas. The path is resolved at run time from where the model was read, following annuallife.TradLife_A.

model_point_table()

The model point table, read from model_point_table.csv.

mort_table()

The base annual mortality rates by sex and age, from mort_table.csv.

A [std] proxy shaped like the ONS UK national life tables, the only fully redistributable UK mortality source; the CMI’s current assured-lives tables are restricted to Authorised Users. Projection.mort_be_factor carries the crude allowance for population mortality being heavier than insured-lives experience.

Mortality is nearly irrelevant on this product - the net amount at risk is a tenth of a percent of the unit fund - unless the guaranteed minimum death benefit rider is enabled, which is why a proxy of this quality is tolerable here and would not be elsewhere. Sorted on read, because Projection.mort_rate indexes into it.

surr_table()

The base annual full-surrender rates by policy year, from surr_table.csv.

Low early, rising as the advised five-to-ten-year holding period completes, then settling at a high ultimate level. A [std] drafting construction: no public UK bond persistency study was fetched. On a product whose every margin line is proportional to the unit fund and to persistency, this is the first assumption to sensitivity-test.