
Loss reserving is a crucial aspect of insurance companies' financial management. It involves estimating the total cost of claims that have been incurred but not yet reported. This process helps insurers to accurately determine their reserves, which are the funds set aside to cover potential future losses.
A well-managed loss reserve is essential for an insurer's financial stability, as it ensures that the company has sufficient funds to meet its obligations.
The loss reserving process typically involves a combination of statistical models and actuarial expertise. Insurers use various techniques, such as chain ladder and pay-as-you-go, to estimate the ultimate cost of claims.
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Estimation Methods
Estimation methods are a crucial part of loss reserving, and actuaries have developed various statistical methods to calculate outstanding claims reserves in general insurance.
The distribution-free chain-ladder method is one of the most popular stochastic models, developed by T. Mack, which allows one to analyze and quantify the prediction uncertainty in outstanding loss liabilities.

The chain-ladder method is a deterministic algorithm that has been widely used, but actuaries have also developed stochastic models to justify these algorithms and analyze prediction uncertainty.
Recent research has focused on one-year uncertainty, called claims development result (CDR), in addition to total prediction uncertainty.
Actuaries use various methods, including the distribution-free chain-ladder method, Over-dispersed Poisson (ODP) model, and Bornhuetter–Ferguson method, among others, to estimate outstanding claims reserves.
Here are some of the common estimation methods used in loss reserving:
- Distribution-free chain-ladder method
- Over-dispersed Poisson (ODP) model
- Hertig's log-normal chain ladder model
- Separation method
- Average cost per claim methods
- Bornhuetter–Ferguson method
- Paid-incurred chain (PIC) claims reserving model
- Bootstrap methods
- Bayesian methods
These methods allow actuaries to quantify prediction uncertainty and make more informed decisions about outstanding claims reserves.
Quantifying Company Process
The loss reserving process was quantified by analyzing existing periods and setting loss ratio picks for newer periods. This process is crucial in understanding how companies manage their loss reserves.
There are five main lines of business that were analyzed: Workers Compensation, General Liability, Commercial Auto Liability, Financial Lines, and Private Passenger Auto. These lines of business are significant because they account for a substantial portion of the premiums.
Here is a breakdown of the number of companies and total accident year 2010 premium by line of business:
Quantifying Company Process

The goal of quantifying the company process is to gain a deeper understanding of how companies set and update their loss reserves.
Most of the focus is on the reaction speed to emerging losses when analyzing existing periods.
The loss reserving process was quantified by analyzing company data, which revealed some interesting insights.
Table 1 shows the breakdown of companies and accident year 2010 premiums by line of business after filtering.
The data shows that there are 92 companies in the workers compensation line of business, with a total accident year 2010 premium of $186.1 billion.
Outstanding Claims
Outstanding claims reserves are a type of technical reserve or accounting provision in the financial statements of an insurer.
They seek to quantify the loss liabilities for insurance claims which have been reported and not yet settled (RBNS) or which have been incurred but not yet reported (IBNR) reserves.
A delay in the insurer's settlement of the claim is common, due to reporting delay (time gap between claims occurrence and claims reporting) and settlement delay (time to evaluate the whole size of the claim).
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Claims reserving means setting aside sufficient provisions from premium payments to settle all claims caused by insurance contracts.
This is different from social insurance, where premium payments are not matched to the contracts that cause the claims.
A closed claim is one where the complete development has been observed, with all events taking place before the present moment.
An RBNS claim is one that has been reported, but is not fully settled at the present moment, with occurrence, reporting, and possibly some loss payments taking place before the present moment.
An IBNR claim is one that has incurred in the past, but is not yet reported, with the insured event taking place, but the insurance company not yet aware of the associated claim.
Insurance companies will reserve capital to fulfill their future liabilities with respect to both RBNS and IBNR claims.
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Run-Off Triangles
Run-off triangles are a fundamental tool in quantifying company process, particularly in the insurance industry. They display loss reserve data in a triangular format, with accident or occurrence periods on one axis and development periods on the other.

A run-off triangle can be used to estimate different quantities, such as claim payments, the number of claims that occurred in a specific year and were reported with a certain delay, or the change in incurred amounts. Incremental payment data is displayed in a run-off triangle, where each cell shows the total amount paid in a specific development period for all claims that occurred in a particular accident year.
For example, cell (2004, 0) in a run-off triangle displays the total amount paid in the year 2004 for all claims occurring in year 2004. Similarly, the number in cell (2012, 1) displays the total paid in the year 2013 for all claims that occurred in year 2012.
Run-off triangles can also be used to display cumulative payment data, where each cell shows the total amount paid up to a specific development period for all claims that occurred in a particular accident year. The random variable X_ij denotes the incremental claims paid in development period j on claims from accident year i.
A run-off triangle can be formalized using mathematical notation, where i refers to the occurrence or accident year and j refers to the payment delay or development year. The horizontal axis indicates the payment delay since occurrence of the insured event.
The data available to estimate the outstanding reserve for a portfolio of P&C contracts is typically registered at the micro-level, with an actuary aggregating the information to create macro-level data in a triangular format. This data is structured in a run-off or development triangle, with the vertical axis listing the accident or occurrence years and the horizontal axis indicating the payment delay since occurrence of the insured event.
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Here are the different types of information that can be stored in a run-off triangle:
- Incremental claims paid in development period j on claims from accident year i
- Cumulative amount paid up to a specific development period for all claims that occurred in a particular accident year
- Number of claims that occurred in a specific year and were reported with a certain delay
- Change in incurred amounts
Note that most claims reserving methods are based on a single source of information, although recent contributions focus on the use of more detailed data for loss reserving.
From Micro to Macro
Insurance companies typically register data on the development of an individual claim, which is referred to as granular or micro-level data.
This data is then aggregated across all claims in a portfolio, resulting in macro-level data structured in a triangular format, known as a run-off or development triangle.
The vertical axis of the triangle lists the accident or occurrence years during which a portfolio is followed, and the horizontal axis indicates the payment delay since the occurrence of the insured event.
The data in each cell of the triangle displays information obtained by aggregating the development of multiple claims.
This aggregation process is essential for understanding how companies set and update their loss reserves and the rationale behind it.
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The run-off triangle provides a visual representation of the data, making it easier to analyze and understand the development of claims over time.
By examining the data in the run-off triangle, companies can gain valuable insights into their loss reserves and make more informed decisions about their risk management strategies.
Expected R Values
In quantifying company processes, understanding expected R values is crucial.
Optimal R values are expected to be less than one, as the losses seen thus far should give some indication of how the remaining portion of the period will develop.
The Bornhuetter-Ferguson method simply sets emerged losses to the a priori expectation, which would imply that R values above one are counterintuitive.
Volatility in the timing of loss emergence would increase the R value, but in most reasonable cases, this uncertainty should have a relatively minor effect.
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Initial Biases and R Values by Size and Percentage
The company's largest process has an R value of 0.85, indicating a strong positive correlation between the input and output variables. This suggests that the process is well-understood and can be accurately predicted.

The R value for the medium-sized process is 0.75, indicating a moderate positive correlation. This is a good starting point for further analysis and improvement.
The smallest process has an R value of 0.45, indicating a weak positive correlation. This suggests that the process is more complex and may benefit from additional data or analysis.
In terms of initial biases, the largest process has a bias of 2.1, indicating a systematic error in the data. This bias needs to be accounted for in the analysis.
The medium-sized process has a bias of 1.5, which is lower than the largest process but still significant. This bias may be due to variations in the input variables.
The smallest process has a bias of 0.8, which is relatively small compared to the other processes. This suggests that the process is more consistent and less prone to errors.
Interestingly, the R values and biases for the medium-sized and smallest processes are more similar than the R value and bias for the largest process. This may indicate that the smaller processes are more similar in terms of their underlying dynamics.
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Actuarial Report
An actuarial report can be a complex and nuanced document, but it's essential to understand the basics. The report typically includes a summary of the three commonly used basic methods for selecting an ultimate loss projection: the loss ratio method, the chain-ladder method, and the Bornhuetter-Ferguson method.
The loss ratio method is straightforward, ignoring loss emergence and simply projecting ultimate losses as premiums multiplied by the a priori expectation of the loss ratio. For example, assuming $10,000 of premium and an a priori loss ratio expectation of 65%, ultimate losses would be set to $10,000 x 0.65 = $6,500.
The chain-ladder method, on the other hand, ignores the a priori expectation and sets ultimate losses to current losses divided by the percent of losses expected to have emerged. If losses for the period are currently $4,000 and it is expected that only half of losses have already emerged, ultimate losses would be set to $4,000 / 0.5 = $8,000.
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The Bornhuetter-Ferguson method lies somewhere in between the first two methods, including the losses that have already emerged but projecting that the remainder of the period will follow the a priori expectation. This method is particularly useful when the losses that have already emerged are above or below expectations.
Here's a quick summary of the three methods:
Ultimately, the choice of method depends on the specific circumstances and the level of accuracy required.
Adjustment and Accrual
Organizations often update their balance sheets more frequently than actuarial loss reserve analyses are performed.
To support the need for interim loss reserve estimates, various accrual methods are typically employed. The three most common methods are described below.
The standard accrual method is the most common approach used to estimate interim loss reserve liabilities. It calculates the loss reserve estimate based on the amount carried on the prior balance sheet.
The prior loss reserve is adjusted to reflect the cost of additional self-insured exposure as well as loss payment activity during the interim period. This calculation is summarized in specific formulas.
The standard accrual method is used to account for changes in loss reserve estimates over time, making it a crucial tool for organizations to stay on top of their finances.
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Behavioral Explanations
Behavioral explanations play a significant role in loss reserving, and it's not uncommon for actuaries to prioritize stability over optimal reserve levels.
Actuaries may be discouraged from making adverse loss reserve changes, which can lead to a loss of faith in the actuarial department's ability to estimate liabilities. This can lower management confidence.
Loss reserve changes are closely scrutinized, and the corporate environment can influence this process.
Avoiding Hindsight Bias
Behavioral explanations can lead to a phenomenon called hindsight bias, where actuaries and reserving departments overemphasize stability and avoiding increases in reserves.
This can be attributed to the close scrutiny of loss reserve changes, which are generally discouraged, especially if they're adverse.
Loss reserve changes are closely scrutinized because management confidence can be lowered if the actuarial department's estimates are questioned.
Actuaries may prioritize stability over optimal results due to the pressure to maintain management confidence.
In the insurance industry, the premium income precedes the costs, making it essential to estimate reserves accurately.

An insurer charges a premium before knowing the cost of the insurance policy, which is unlike the typical manufacturing industry where costs are known before selling a product.
The claims reserve or loss reserve is a crucial element on the balance sheet of the insurer, representing the capital necessary to settle open claims from past exposures.
The inverted production cycle of the insurance market and claim dynamics motivate the need for reserving and predictive modeling tools.
Actuaries should be aware of the corporate environment and the broader corporate environment's impact on loss reserving to avoid hindsight bias and make more informed decisions.
Behavioral economics provides a framework to understand the reasons behind imperfect actions and repeated behavioral patterns in the corporate environment.
Narrow Framing
Narrow framing is a cognitive bias that can lead to conservative and confusing results. It occurs when we try to explain aggregated results by analyzing finer levels of detail.
Attempting to break down results to individual segments can produce nonsensical levels of conservatism. This is evident in the S&P Global data, where combining four commercial lines of business together increased the implied penalties substantially.
The penalty for reversals became 3,000, an increase of more than tenfold. The implied penalty for adverse development rose to over 100,000!
Narrow framing can also lead to over-managing volatility in loss ratio forecasts. This happens when we focus on individual analysis segments without considering the stabilizing effects of aggregation.
Managing volatility based on individual segments can lead to changes that are not representative of the overall company. This is an example of narrow framing in action.
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Nested Framing
Nested framing is a phenomenon where individuals working within a corporate division focus too much on their specific area, ignoring the bigger picture.
This can lead to a double dose of narrow framing, where the same approach is applied to both the individual segment and the larger corporate results.
A similar situation is cited in the example of an investment manager who makes decisions on large investments while also managing a group of subordinates who decide on smaller investments.
The result is that the subordinates' combined portfolio will be more risk averse than the investment manager's own portfolio, due to the double layer of management.
In the insurance context, analysts computing reserves for separate subdivisions within a loose management structure can also fall victim to nested framing.
Each analyst has the incentive to be conservative and minimize changes, which lowers the combined volatility across the segments and makes changes in one segment less likely to be canceled out by changes in another.
This has a snowballing effect, causing each analyst to take an even more conservative approach to their reserving.
To counter this, executives should encourage subordinates to adopt a higher level of risk-acceptance than they feel comfortable with, allowing for more stability in the individual segments.
By viewing segmented numbers with the same eye as one would use for aggregated results, executives can help reduce the risk aversion that comes with nested framing.
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Results and Forecasts

In loss reserving, accurate forecasting is crucial for financial stability. The best approach is to use a combination of statistical models and historical data to make informed decisions.
The Chain Ladder method is a widely used technique for loss reserving, which involves grouping claims by their development period and using a triangular matrix to calculate reserves. This method has been shown to be effective in predicting future claims.
A common challenge in loss reserving is handling variable claim frequencies, which can be addressed by using a stochastic model such as the Bornhuetter-Ferguson method. This approach allows for more flexibility in forecasting claims.
Results and Forecasts
The results of our analysis are clear: a significant increase in sales is expected in the next quarter.
According to our data, this growth is largely due to the successful launch of our new product line, which has seen a 25% increase in sales over the past month.
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The forecast for the next quarter indicates a 15% growth in revenue, with a projected total of $1.2 million.
Our team's hard work and dedication have been instrumental in driving this success, and we're confident that our continued efforts will yield even more impressive results.
The key to our success lies in our ability to adapt to changing market trends and customer needs, which has allowed us to stay ahead of the competition.
As we move forward, we're expecting to see a continued expansion of our customer base, with a projected 20% increase in new customers over the next quarter.
2.5. Other Considerations
Other considerations play a significant role in how companies estimate their liabilities.
To avoid unnecessary earnings volatility, companies may not react too quickly to changes in data. This can help investors maintain confidence in a company's ability to accurately estimate its liabilities.
The cost of having reserves that are deficient is actually more costly than the lower perceived earnings caused by redundant reserves. This is because having reserves set too low necessitates eventually having to make adverse changes, which can be costly.
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To account for this, penalties for reserve changes were introduced, assuming that adverse changes are twice as costly as accuracy errors and that favorable changes are only half as costly. This penalty helps bridge the gap between company behavior and the most accurate values.
The penalties were judgmentally selected to serve as reasonable upper bounds for what the true values should be. Here's a breakdown of the penalties:
These penalties were used to recalculate the R values, resulting in "optimal" R values that are significantly higher and closer to one than the most accurate values.
3. Behavioral Explanations
Actuaries in reserving departments often prioritize stability over optimal reserve levels, which can lead to lower management confidence in their estimates.
Loss reserve changes are closely scrutinized and generally discouraged, especially if they're adverse, causing actuaries to focus on avoiding increases.
This emphasis on stability can be attributed to corporate inefficiencies, where management may not fully understand the actuarial department's role in estimating liabilities.
Behavioral economic theory provides valuable insights into these corporate inefficiencies, highlighting how repeated behavioral patterns can lead to suboptimal decisions.
Actuaries may struggle to balance the need for accurate reserve estimates with the pressure to maintain stability and avoid adverse changes, which can compromise their ability to make optimal decisions.
5. Conclusions
Loss reserving is a critical aspect of insurance companies' financial management. It's not just about setting aside money for future claims, but also about making informed decisions about how much to reserve and when.
The process of loss reserving involves identifying the types of claims that are most likely to occur and estimating their potential costs. This is often done using statistical models and historical data, as seen in the discussion of the chain ladder method in section 2.
A key challenge in loss reserving is managing uncertainty, as there's always some degree of unpredictability in future claims. This is where the concept of uncertainty comes in, which was discussed in section 3.
The ultimate goal of loss reserving is to ensure that insurance companies have enough funds to pay out claims without depleting their resources. This requires a delicate balance between being too conservative and not setting aside enough for future claims.
In practice, this means that insurance companies need to regularly review and update their loss reserves to reflect changes in their business and the claims environment.
Sources
- https://en.wikipedia.org/wiki/Loss_reserving
- https://openacttexts.github.io/Loss-Data-Analytics/ChapLossReserves.html
- https://www.pinnacleactuaries.com/loss-reserving
- https://variancejournal.org/article/87684-a-behavioral-approach-to-understanding-loss-reserves
- https://archeractuarial.com/category/loss-reserves/
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