1/212
Good luck handsome!
Name | Mastery | Learn | Test | Matching | Spaced | Call with Kai | Chat |
|---|
No analytics yet
Send a link to your students to track their progress
Benktander Pros and Cons
Advantages
BG MSE is almost always smaller than BF or CL
BG MSE is almost as small as the optimal credibility reserve
Better approximation of the exact Bayesian procedure
Superior to CL since it gives more weight to the a priori expectation of ultimate losses
Superior to BF since it gives more weight to actual loss experience
Disadvantages
Requires an a priori estimate of ultimate losses
Benktander: if c* > p_k / 2
then BG reserve has a smaller MSE than BF reserve
Benktander: Esa Hovinen Reserve
R_eh = c * R_cl + (1-c) * R_bf
If c = p_k then R_eh = R_gb
Benktander: Chain Ladder Ultimate Formula





Hurlimann ELR
If using BF 🡪 Use the selected LDF and A Priori estimates
If using Cape Code 🡪 Calculate ELR using age-to-age factors instead of calculating mk and pi
Sum (latest diagonal loss figures) / sum(used premium)


Hurlimann Individual Resersve


Hurlimann Collective Reserve
ADVANTAGE OVER BF: BASED ON OBJECTIVE DATA

HURLIMANN BENKTANDER CREDIBILITY

HURLIMANN NEUHAUS CREDIBILITY
ASSUMES CONSTANT ELR

HURLIMANN OPTIMAL CREDIBILITY

HURLIMANN - Z_opt, t_opt, f_i


HURLIMANN


HURLIMANN


HURLIMANN
Optimal weights minimize MSE between estimated & true reserves → closest to 1 is optimal


HURLIMANN

BROSIUS - LEAST SQUARES PROS
Advantages
More flexible than link ratio (CL), budgeted loss (ELR), and BF methods
Places more (or less) credibility on the loss experience as appropriate
Produces more reasonable results when data has severe random, year-to-year fluctuations
BROSIUS - LEAST SQUARES METHOD
Use =SLOPE & =INTERCEPT to calculate the ult loss ratio by AY, iteratively 🡪
Start with more mature AY’s to add more data points in later iterations of the process
Assumes no systematic shifts in the book of business
If significant premium growth 🡪 convert losses to Loss Ratios
Adjust incurred loss data for inflation so all AY’s are on a constant-dollar basis
If there is significant growth in the book of business, you should divide by an exposure basis
INTERCEPT < 0, use the link ratio (CL) method
SLOPE < 0, use the budgeted loss (ELR) method
BROSIUS - CREDIBILITY ON THE LINK RATIO

BROSIUS - HUGH WHITE’S QUESTION
If reported losses come in higher than expected,
Budgeted Loss method – reserve estimate will decrease but ultimate loss stays the same
BF Method – reserve does not change; ultimate loss increases by difference in actual and expected loss
Link Ratio – ultimate loss estimate increases in proportion to the excess losses by applying the LDF
BROSIUS - LINEAR APPROXIMATION
RESERVE = X - L(x)

BROSIUS - LINEAR APPROXIMATION - HOW LARGE LOSS CAN CHANGE THE LOSS RESERVES

BROSIUS - LINEAR APPROXIMATION KEY POINT
THE LEAST SQUARES METHOD IS THE BEST LINEAR APPROX TO THE BAYESIAN ESTIMATE
BROSIUS - LINEAR APPROXIMATION ADVANTAGES

BROSIUS - BAYESIAN CREDIBILITY IN A CHANGING SYSTEM

BROSIUS - BAYSEIAN CREDIBILITY IS APPROPRIATE FOR
A NEW LINE OF BUSINESS
THERE IS A CHANGE IN THE BOOK MOVING FORWARD
BROSIUS - CASELOAD EFFECT

FRIEDLAND (REINSURANCE) - REINSURANCE STAKEHOLDERS
Internal management – sound reserves affect all areas of reinsurer operations (pricing, underwriting, strategic planning, financial decision-making, etc.)
Investors – appropriately stated reserves are essential so that investors can properly evaluate the reinsurer’s balance sheets and income statements for their decision-making
Insurance regulators – regulators rely on the financial statements of reinsurers to properly supervise the reinsurance market
Rating agencies – if a reinsurer reports significant adverse reverse developments over time that reduce capital leaving the reinsurer in a weakened position, it could face a rating downgrade
FRIEDLAND (REINSURANCE) - FUNCTIONS OF REINSURANCE
Promote stability – ceding company stabilizes its loss experience; decreased proability of ruin
Increase capacity – by ceding, a company increases capacity to write more business / high limit policies
Protect against CATs – protect ceding companies from CATs & casualty loss occurrences w/ multiple insureds
Manage Capital and Solvency Margin
Pass risk of large losses to the reinsurer 🡪 frees capital since less is required to support policies written
Ceded commission acts as a transfer of statutory surplus to the cedant from the reinsurer
Ceded premium reduces cedant net premium-to-surplus ratio, allowing them to write more business
Access technical expertise – reinsurers have expertise in underwriting, marketing, claims, prevention, pricing
Other functions – withdrawing from a line of business, geographic area, or production source
FRIEDLAND (REINSURANCE) - TYPES OF REINSURANCE: HOW THEY WORK - TREATY
Cede all business arising from LOBs that fall within terms of the treaty subject to treaty limits
No underwriting by reinsurer of individual risks
Cedant obliges to cede risk under the treaty terms; reinsurer obliges to automatically accept it
FRIEDLAND (REINSURANCE) - TYPES OF REINSURANCE: HOW THEY WORK - FACULTATIVE
Cedant and reinsurer have the option (faculty) to accept/reject individual submissions
Each policy has their own negotiated agreement
Primarily used to increase capacity, typically for high-value and hazardous commercial risks
Facultative automatic – a bordereau of risks ceded is submitted to the reinsurer, which has limited rights to decline individual risks
Facultative obligatory treaty – a treaty under which the cedant has the option to cede or not cede individual risks. The reinsurer must accept any risks that are ceded
FRIEDLAND (REINSURANCE) - TYPES OF REINSURANCE: HOW THEY WORK - PROPORTIONAL
Increases capacity & manages capital and solvency margins to provide surplus relief
Premiums & losses shared based on cession percentage.
The reinsurer pays a ceding commission to reimburse cedant for expenses underlying the policy
Types
Quota share – agreed % of each risk is ceded for the LOBs included in the treaty
Surplus share – cede the surplus amount of risk above the retained line subject to maximum ceded % and limit
FRIEDLAND (REINSURANCE) - TYPES OF REINSURANCE: HOW THEY WORK - NON - PROPORTIONAL
Provides stability by protecting losses above a limit for risks ceded
Loss ceded based on size of loss and premium is not proportional
Types
Excess per Risk – excess of loss above a retention for each risk
Excess per Occurrence – protects from accumulation of loss from single occurrence
Excess per CAT – protects from accumulation of loss from single CAT
Annual Aggregate Excess of Loss (Stop-Loss) – cedant loss won’t exceed a threshold
Clash – attaches above all other policy limits; Protects against multiple claims from multiple insureds
Components of a clash event
Loss must have multiple policies by one insured or similar policies held by multiple insureds
Losses are traceable to and the direct consequence of a specific event
Event takes place within a specific timeframe
FRIEDLAND (REINSURANCE) - TYPES OF REINSURANCE: HOW THEY WORK - FINITE RISK REINSURANCE
Features include:
Risk transfer and risk financing in a multi-year contract
Incorporates the time value of money and investment income
Limited assumption of risk by the reinsurer
Reinsurer and ceding company share results
Includes run-off solutions, which transfer reserve development risk to the reinsurer. Reasons for run-off include
Corporate restructuring
Mergers & acquisitions
Discontinuations of lines of business
Erratic changes in the valuation/cost of a liability
Loss portfolio transfers
transfers all (or portion) of liability for future loss payments on losses already incurred
relieves cedent of uncertainty in loss reserves and relieves capital
Adverse development cover
ceding company is reimbursed for losses excess a retention but no transfer of the loss reserves to the reinsurer
often used for M&A to transfer the risks of timing and adverse reserve development
FRIEDLAND (REINSURANCE) - REINSURANCE CONCEPTS & CONTRACT PROVISIONS
Inure to the benefit of – determine the ordering of the contracts
Losses occurring during vs risks-attaching – determines coverage
Subscription percentage – reinsurance policy where risk is shared by multiple reinsurers, each of whom have a subscription percentage
Allows diversification of credit risk
Coverage may be more than one reinsurer is willing to assume
Commutation clause – ending reinsurance contract early
FRIEDLAND (REINSURANCE) - REASONS FOR COMMUTATION
Cedant
Exit LOB
Manage reserve for transfer or sale
Avoid credit risk of reinsurer
Better manage claims and claims-related expenses
Reinsurer
Terminate relationships with cedants
Protect from insolvency of a cedant
Avoid dispute with cedant about future loss development
FRIEDLAND (REINSURANCE) - SUFFICIENCY, RELIABILITY, DATA CHALLENGES
Sufficiency – data includes all info needed for actuarial work
Reliability – data is sufficiently complete, consistent, and accurate for the purposes of the work
Data should be validated and reviewed for consistency, completeness and accuracy
Challenges
Influence of change in operations and environment
operational changes for ceding insurers and reinsurers
changes in legal/economic environment of ceding companies that impact loss
Different IT systems, terminology
Reporting lags & gaps in reporting
Manuscript nature of reinsurance policies
contract wording can be different by contract making it difficult to aggregate data
Other experience typically excluded
run-off data
FRIEDLAND (REINSURANCE) - HOMOGENEITY AND CREDIBILITY DATA
DATA SHOULD BE SEGMENTED INTO GROUPS WITH SIMILAR CHARACTERISTICS OF LOSS EXPERIENCE SUCH AS COVERAGE, REPORTING, SEVERITY, AND VOLUME
FRIEDLAND (REINSURANCE) - COMPARISON OF DEVELOPMENT FACTORS & PATTERNS (IN TERMS OF VOLATILITY)
Reinsurance > Primary at earlier maturities
Paid > Reported for Reinsurance business
Due to longer reporting/payment patterns for reinsurance b/c of lags in reporting to the reinsurer
Non-Proportional Treat & Facultative > Proportional treaty
Greater volatility means greater uncertainty in projected ultimate using development method
CAT > Ex CAT
Development methods are often not appropriate for CATs
FRIEDLAND (REINSURANCE) - IMPLICATIONS OF VOLATILITY IN LOSS DEVELOPMENT
Greater volatility in projected Ultimate loss results in greater range in indicated IBNR and Total Unpaid for
Reinsurance compared to primary
Non-proportional & fac compared to proportional
CAT reinsurance compared to ex CAT
FRIEDLAND (REINSURANCE) - PROPORTIONAL REINSURANCE - SURPLUS SHARE TREATY

FRIEDLAND (REINSURANCE) - EXCESS PER RISK - ALAE IS HANDLED IN ONE OF THREE WAYS
Included with loss before calculating excess of loss coverage
Included pro-rata
Not included
FRIEDLAND (REINSURANCE) - ULTIMATE LOSS WITH CAT ADJUSTMENT
Step 1: by treaty year, subtract out REPORTED large CAT losses from CAT losses
Step 2: develop CAT losses using a CDF and add in the ESTIMATED ULTIMATE of the large CAT losses afterwards
Keep in mind
For a reinsurer covering catastrophe losses, the large catastrophe losses are included in the development triangle for property catastrophe losses when calculating LDFs.
The timing within a year of large loss events can also distort loss triangles
The actuary can get estimates of ultimate losses for large catastrophes from the claims team and from catastrophe models.
FRIEDLAND (REINSURANCE) - CURRENCY EXCHANGE RATE CHANGES
Use the prevailing exchange rate (latest diagonal) to convert currencies; avoiding distortion
CLARK - PROCESS VARIENCE
VARIANCE DUE TO RANDOMNESS OF THE INSURANCE PROCESS
Loss model assumptions
Assume incremental losses have a constant variance/mean ratio, 2
Assume incremental losses follow an ODP (over-dispersed Poisson) model
CLARK - PARAMETER VARIANCE
VARIANCE IN THE ESTIMATE OF THE PARAMETERS
Calculated based on the Rao-Cramer lower-bound approximation, using the second derivative information matrix
The info matrix is used to calculate the covariance matrix
The actual calculation of the parameter variance is too complex for the exam
CLARK - DISCOUNTED RESERVES
CV of discounted reserves < CV of undiscounted reserves
Because the tail payout has the greatest parameter variance, but is discounted the most
CLARK - KEY MODEL ASSUMPTIONS
Incremental losses are iid
Independent – one period doesn’t impact surrounding periods (this fails if there are calendar year effects such as inflation)
Identically distributed – assume the same emergence pattern for all AYs
Variance/Mean Scale Parameter, 2, is fixed and known
Variance estimates use approximation to the Rao-Cramer lower bound
CLARK - LDF METHOD

CLARK - LDF METHOD - GRAPHICAL TESTS
Residuals should be random around zero & have constant variance to assume the growth curve is appropriate
Examples of graphs:
Incremental age
Expected Loss in Each Increment Age
Calendar year
CLARK - CAPE COD METHOD

CLARK - CAPE COD METHOD - PREMIUM MUST BE ON-LEVELED SO THAT WE CAN ASSUME A CONSTANT ELR ACROSS ALL AYs
CLARK - CAPE COD METHOD - COMPARED TO THE LDF METHOD
Cape Cod has lower parameter variance because there are fewer parameters to estimate and it uses more information (on-level premium)
CLARK - TRUNCATION POINT MAKES IT SO
WE DON’T EXTRAPOLATE TOO MUCH INTO THE TAIL OF THE G(X) DISTRIBUTION
CLARK - NORMALIZED RESIDUALS

CLARK - NORMALIZED RESIDUAL GRAPHS
FOR ALL GRAPHS, RESIDUALS SHOULD BE AROUND ZERO WITH NO PATTERNS OR AUTOCORRELATIONS
Normalized Residuals vs Increment Age
Tests how well loss emergence curve fits incremental losses at different development periods.
See whether the curve overestimates for some development periods and underestimate for others
Normalized Residuals vs Expected incremental loss
Check if variance/mean scale parameter is constant.
If not constant, see residual clusterd closer to zero at either high or low expected incremental losses
If so this assumption may not be appropriate
Normalized Residuals vs Calendar year
Test for diagonal effects.
High/low residuals for a specific calendar year might be evidence of calendar year effects
CLARK - VARIANCE OF PROSPECTIVE LOSSES

CLARK - VARIANCE OF CY DEVELOPMENT ADVANTAGES
THE MODEL CAN BE TESTED IN A RELATIVELY SHORT TIME
CLARK - BEST FIT PARAMETERS MLE - CALCULATE LOG-LIKELIHOOD

CLARK - BEST FIT PARAMTERS MLE - TWIST
DATA PRESENTED IN THOUSANDS! TRANSFORM THE DATA SINCE THIS WILL AFFECT THE MLE TERM
MACK CHAIN LADDER - MACK ASSUMPTIONS
Expected losses in the next development period are proportional to losses-to-date
The same LDF is used for each AY
Uses most recent losses-to-date to project losses, ignoring losses as of earlier dev periods
Test: linear relationship between Loss_k+1 & Loss_k through the origin (no intercept)
Losses are independent between accident years
Use the calendar-year test to see if there are calendar year effects such as changes in claims handling
Variance of losses in the next development period is proportional to losses-to-date by a factor that varies by age
Plot the residual graph with this assumption 🡪 should be
random around zero
without trends
MACK CHAIN LADDER - DISADVANTAGE OF MACK METHOD COMPARED TO BOOTSTRAP METHOD
IT DOESN’T TELL US ABOUT THE SHAPE OF THE LOSS RESERVE DISTRIBUTION, ONLY THE MEAN AND STANDARD DEVIATION
MACK CHAIN LADDER - WEAKNESSES OF THE CHAIN LADDER METHOD
ESTIMATOR OF THE LAST 2 OR 3 LDFs RELY ON VERY FEW OBSERVATIONS
DOESN’T WORK WELL FOR THE MOST RECENT AY WHERE LOSSES-TO-DATE PROVIDE A VERY UNCERTAIN BASE TO PROJECT ULTIMATE LOSSES
MACK CHAIN LADDER - RESIDUAL TEST (WEIGHTED RESIDUALS)

MACK CHAIN LADDER - CALENDAR YEAR TEST

MACK CHAIN LADDER - CALENDAR YEAR EFFECT EXAMPLES
Major changes in claims handling practices
Major changes in setting case reserves
Unexpectedly high (or low) inflation
Significant changes due to court decisions
MACK CHAIN LADDER - RESERVE CONFIDENCE INTERVAL

MACK CHAIN LADDER - EMPIRICAL LIMITS
C.I. TOP = CUMULATIVE LOSS * CDF OF MAX (AGE TO AGE FACTORS)
C.I. BOTTOM = CUMULATIVE LOSS * CDF OF MIN (AGE TO AGE FACTORS)
MACK CHAIN LADDER - MSE CALCULATION

MACK CHAIN LADDER - OVERALL RESERVE MSE - IMPORTANT CONCEPT
MSE of the total reserve > sum of MSE from individual AYs
Because the same LDFs are used for all AYs, the loss reserve estimates are positively correlated between AYs, increasing the total MSE
MACK CHAIN LADDER - CORRELATION ADJACENT LDFs (SPEARMAN’S RISK)
The correlation of adjacent LDFs is a test of Mack’s 1st assumption that losses in the next development period are proportional to losses-to-date
Mack Correlation of Adjacent LDFs test looks at the triangle as a whole, not at each column-pair
It’s more important to know if correlation between LDFs prevails throughout the triangle

VENTER FACTORS - 6 TESTABLE IMPLICATIONS OF THE MACK ASSUMPTIONS: IF ANY FAIL THEN MACK DOESN’T HOLD UP
VENTER FACTORS - 1. SIGNIFICANCE OF DEVELOPMENT FACTORS (ASSUMPTION 1)

VENTER FACTORS - 2. SUPERIRORITY TO ALTERNATIVE LOSS EMERGENCE (ASSUMPTION 1)
GOODNESS OF FIT TEST: USE ADJ SSE, AIC, BIC (LOWER FIGURES ARE BETTER)
LEAST SQUARES: IF THE CONSTANT IS SIGNIFICANT, THE EMERGENCE PATTERN IS MORE STRONGLY SUPPORTED THAN CL
PARAMETERIZED BF: INCREMENTAL LOSS = f(d)*h(w)
CAPE COD: REQUIRES STABLE LEVEL OF LOSS EXPOSURE
ADDITIVE CL PRODUCES SAME RESULTS AS CAPE COD
VENTER FACTORS - 3. LINEARITY OF THE MODEL: RESIDUALS VS LOSS_K (ASSUMPTION 1)
ASSUMPTION 1 ASSUMES INCREMENTAL LOSS EMERGENCE IS LINEARLY PROPORTIONAL TO LOSS-TO-DATE
IF RESIDUALS SHOW A NON-LINEAR PATTERN, THEN INCREMENTAL LOSS EMERGENCE IS A NON-LINEAR FUCNTION OF LOSS-TO-DATE
VENTER FACTORS - 4. STABILITY OF DEVELOPMENT FACTORS: RESIDUALS VS TIME (ASSUMPTION 1)
Plot residuals against time 🡪 a pattern of high/low residuals indicates instability and is evidence against using the same dev factor for all AYs
STATE-SPACE MODEL: Compares the degree of instability of the observations around the current mean to the degree of instability in the mean itself over time. This helps determine whether to use all of the data or a weighted average that favors more recent years
VENTER FACTORS - 5. CORRELATION OF DEVELOPMENT FACTORS (ASSUMPTION 2)
IF THERE IS A SIGNIFICANT CORRELATION BETWEEN DEV FACTORS AT DIFFERENT AGES, THEN THIS IS EVIDENCE AGAINST CL METHODS
VENTER FACTORS - 6. SIGNIFICANTLY HIGH / LOW DIAGONALS (CY EFFECTS) (ASSUMPTION 2)
IF ANY OF THE DUMMY VARIABLE ARE STATISTICALLY SIGNIFICANT, THEN THIS INDICATES CY EFFECTS
VENTER FACTORS - INFLATION MODEL

VENTER FACTORS - CORRELATED DEV FACTORS

VENTER FACTORS - TESTING FOR CORRELATION IN THE ENTIRE TRIANGLE

VENTER FACTORS - WHY IS IT IMPORTANT TO TEST CORRELATION IN THE ENTIRE TRIANGLE

VENTER FACTORS - PARAMETERIZED BF - CONSTANT VAIRANCE

VENTER FACTORS - PARAMETERIZED BF: f(d)h(w) - Var f(d)h(w)

VENTER FACTORS - TESTING FOR SIGNIFICANTLY HIGH/LOW DIAGONALS - KEEP IN MIND
IF ABS(COEFFICIENT) > 2 * STD DEV (COEFFICIENT) THEN THE DIAGONAL IS SIGNFICANTLY HIGH (OR LOW)
THIS SUPPORTS THE CL METHOD ASSUMPTION THAT AY’S ARE INDEPENDENT
VENTER FACTORS - GOODNESS OF FIT TEST
VENTER FACTORS - SSE
SUM [(Actual Incremental - Expected Incremental)²]; do not calculate the first dev period
VENTER FACTORS - ADJUSTED SSE
SSE / (N-P)²
N = # OF OBSERVATIONS IN THE SSE TRIANGLE
P = # OF PARAMETERS
Smallest Adjusted SSE is best
Parameterized BF = 2 * (#AY -1)
Chain Ladder = #AY - 1
Cape Cod = #AY -1
VENTER FACTORS - AIC
AIC = SSE * e^(2p/n)
Does not penalize enough for having too many parameters
Smallest AIC is best
VENTER FACTORS - BIC
BIC = SSE * n^(p/n)
Smallest BIC is best
SHAPLAND - GOAL OF BOOTSTRAP MODEL
create a full distribution of possible loss reserve outcomes, not just a point estimate or the mean and variance like in the Mack approach
Do this by sampling residuals from the original loss triangle to create simulated loss triangles, one for each iteration in the simulation
Then, an estimated loss reserve is calculated for each iteration
SHAPLAND - BOOTSTRAP DIAGNOSTICS: PURPOSE
Test model assumptions
Gauge how well the model fits the data
Help guide adjustments of model parameters
SHAPLAND - BOOTSTRAP DIAGNOSTICS: RESIDUAL GRAPHS
residuals should be random around zero for the following graphs
Residuals vs CY
Residuals vs Dev Period (look for heteroscedasticity)
Residuals vs AY
Residuals vs Fitted Incremental Loss
SHAPLAND - BOOTSTRAP DIAGNOSTICS: NORMALITY TEST
Normality Test
Normality isn’t required but Shapland mention this as a diagnostic to review
If residuals are close to normal you should see
Normality plot with residuals in line with the diagonal line
High R^2 value and p-value greater than 5%
AIC and BIC can be used to compare different models to see which model is closest to Normal while penalizing for extra parameters
SHAPLAND - BOOTSTRAP DIAGNOSTICS: OUTLIERS
Use a box-whisker plot to identify outliers
Outliers may simply be extreme but realistic values – in which case they should stay in the data
Remove the value and treat like a missing value or
Identify and exclude outliers from the LDF calculation and residual calculations, but re-sample the corresponding incremental loss for the sampled triangles
SHAPLAND - BOOTSTRAP DIAGNOSTICS: PARAMETER ADJUSTMENT
Look at residual graphs and adjust parameters in the model by adding or removing additional parameters
SHAPLAND - BOOTSTRAP DIAGNOSTICS: MODEL RESULTS
Standard error
should increase from older to more recent years
Total standard error should be larger than the standard error for any individual year
CoV
should decrease from older to more recent years
Total CoV should be less than any individual year
CoV could rise in the most recent years due to
Parameter uncertainty in most recent years could overpower process uncertainty
The model could be overestimating uncertainty
SHAPLAND - MULTIPLE MODELS: MODEL RISK
risk that the model doesn’t reflect the “true” loss-generating process for future losses. Weighing together multiple reasonable models helps address this
SHAPLAND - GLM SETUP
Step 1: Calculate incremental loss triangle
Step 2: Calculate the log-link triangle (natural log of each incremental loss)
Step 3: Specify the model framework
Step 4: Model specification (Y=X * A)
Step 5: Set up the Solution Matrix (Weight Matrix)
Step 6: Discuss how the α and β parameters are solved for