Couret.Venter — BattleActs Exam 8 Forum

2012Q5

tracyguo8 — Fri, 29 Sep 2023 23:32:19 +0000

Hi there,

For Part (b), the solution calculates PT relative to TT as (pure premium relativity for HG) * (credibility relativity from multi-dimensional).

Could you please explain what do those "Predicted" relativity under multi-dimensional output actually mean, and ultimately why do we need to multiply by the (pure prem relativity for HG) instead of just using the credibility relativity from multi-dimensional?

Are those the relativity to TT or relativity to HG?
Are these relativities the output from the whole "Credibility Considerations" section in the Battlewiki, i.e. calculating the EPV, VHM, variance, covariance matrix etc?
Why do we need to multiply by the (pure prem relativity for HG) instead of just using the credibility relativity from multi-dimensional? Is it because the sample means are normalized within the HG? What if the sample means are not normalized within HG, can we just directly use the credibility relativity from multi-dimensional "Predicted"?

Thanks.

2011.Q2

twitte — Tue, 17 Oct 2023 10:59:55 +0000

In this question, what is the purpose of calculating the SSE of the holdout sample vs 1.00 i.e. Sum[(1-.6)^2+(1-.8)^2).... I don't get what that tells us - just that having real relativities for these quintile groups (rather than 1.00) makes sense to do? However it is a different comparison.

In my solution I just calculated the SSE for Raw - HO and Cred - Raw. This treats the HO sample relativities as the "true values" and thus allows us to compare which method got closer to that.

I feel like its things like this where I lose a few partial points - what am I missing here?

Quintile Test

tracyguo8 — Fri, 29 Sep 2023 23:39:31 +0000

Hi there,

Could you please elaborate on step (4) of the Quintile Test in the Battlewiki?

"Calculate Vquintile and Vquintile, holdout. Calculate v^quintile and vh^ as weighted averages of vi^ using the TT injury counts for the weights."

I guess this is related to the question that I asked in another thread, if the relativities in the "Predicted" column in the multi-dimensional table are calculated using vi (the estimated population injury type mean ratio to TT for class i), why do we need to multiply by the pure premium relativity for the HG containing the class?

Thanks!

2014 q4

Ayesha — Tue, 29 Aug 2023 13:04:37 +0000

I don't understand what the question is asking for. Can you please explain

Thanks

Deriving Multi-Dimensional Weights

ecasp12 — Wed, 15 Sep 2021 11:41:02 +0000

In the Couret and Venter paper, the derivation of the optimal credibility weights takes up ~2 pages, but there is no example of how to derive the optimal credibility weight. I have a difficult time understanding the covariance matrices presented, since there's no example of how I would do the calculations to get the optimal weight. The wiki summary in the "Credibility Considerations" section mentions that we should know the EPV and VHM formulas and how to apply them.

Do you think this is a likely or possible exam topic? If you think this is likely to be on the exam, would it be possible to get a small example of how to work through the calculations?