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Stephen Richards

Managing Director

Articles written by Stephen Richards

Spotting quality issues with limited data

In an earlier posting I showed how to use the Kaplan-Meier function to identify subtle data problems.  However, what can you do when you don't have the detailed information to build a full survival curve?
Tags: Filter information matrix by tag: data validation, Filter information matrix by tag: survival rates, Filter information matrix by tag: standard table

S2 mortality tables

The CMI has released the long-awaited S2 series of mortality tables based on pension-scheme data.  These are the first new tables since the CMI changed its status (the S2 series is only available to paying subscribers, unlike prior CMI tables). 
Tags: Filter information matrix by tag: S2 Series, Filter information matrix by tag: S1 Series, Filter information matrix by tag: CMI, Filter information matrix by tag: mortality improvements

The perils of parameter interpretation

With some notable exceptions, such as the Kaplan-Meier estimator, most mortality models contain parameters. In a statistical model these parameters need to be estimated, and it is a natural thing for people to want to place interpretations on those parameter estimates. However, this can be tricky, as parameters in a multi-parameter model are dependent on each other.

Tags: Filter information matrix by tag: Lee-Carter, Filter information matrix by tag: parameterisation

Spotting hidden data-quality issues

The growing market for longevity risk-transfer means that takers of the risk are keenly interested in the mortality characteristics of the portfolio concerned. The first thing requested by the risk-taker is therefore detailed data on the portfolio's recent mortality experience.  This is ideally data extracted on a policy-by-policy basis.

Tags: Filter information matrix by tag: data validation, Filter information matrix by tag: Kaplan-Meier

Reducing uncertainty

The motto of the old UK Institute of Actuaries was certum ex incertis, i.e. certainty from uncertainty. I never particularly liked this motto — it implied that certainty can be obtained from uncertainty, whereas uncertainty is all-too-often overlooked.

Tags: Filter information matrix by tag: estimation error, Filter information matrix by tag: survival models

Out of line

Regular readers of this blog will be in no doubt of the advantages of survival models over models for the annual mortality rate, qx. However, what if an analyst wants to stick to the historical actuarial tradition of modelling annualised mortality rates?
Tags: Filter information matrix by tag: GLM, Filter information matrix by tag: linearity, Filter information matrix by tag: survival models

Haircut or hedge-trim?

Richard Willet's observation last year on the restatement of population estimates was picked up again recently by the BBC. Amongst the implications of the missing nonagenarians are some potentially interesting consequences for index-based longevity hedges.
Tags: Filter information matrix by tag: ONS, Filter information matrix by tag: longevity hedge, Filter information matrix by tag: basis risk, Filter information matrix by tag: S-forward

Health experiments

One interesting aspect of Scottish devolution is the different path charted in health policy.

Tags: Filter information matrix by tag: Scotland, Filter information matrix by tag: alcohol, Filter information matrix by tag: smoking

Enhancement

An oft-overlooked aspect of statistical models is that parameters are dependent on each other. Ignoring such dependencies can have important consequences, and in extreme cases can even undermine assumptions for a forecasting model. However, in the case of a regression model the correlations between regressor variables can sometimes have some unexpectedly positive results.

Tags: Filter information matrix by tag: survival models, Filter information matrix by tag: enhancement, Filter information matrix by tag: AIC

No smoking without fire

Socio-economic differentials in life expectancy have a long history in the United Kingdom. A large part of this over the last few decades has been stark differences in smoking rates — people of a high socio-economic status are much less likely to smoke, resulting in longer life expectancy.
Tags: Filter information matrix by tag: smoking, Filter information matrix by tag: e-cigarettes, Filter information matrix by tag: mortality improvements