[[Actuarial Notes Wiki|Wiki]] / [[Exam 5 (CAS)]] / **Severity Analysis**
## Definition
==Severity Analysis== is the examination of average claim costs (total losses divided by claim counts) to understand trends in claim size and identify changes in the cost per claim.
## Formula
```
Average Severity = Total Incurred Losses / Number of Claims
Can analyze:
- By accident year
- By development age
- By coverage type
- By geography
```
## Uses
### Trend Analysis
```
Track severity changes over time:
- Medical cost inflation
- Wage inflation
- Social inflation
- Coverage limits impact
Annual Severity Trend = (Current Severity / Prior Severity)^(1/years) - 1
```
### Reserve Testing
```
Projected Ultimate Severity × Projected Ultimate Counts = Ultimate Losses
Consistency check:
- Do severity trends match expectations?
- Are counts developing reasonably?
- Does product match total loss estimates?
```
## Example
```
Auto Bodily Injury Analysis:
AY Claims Losses Avg Severity
2021 1,000 $5,000,000 $5,000
2022 1,050 $5,775,000 $5,500
2023 1,100 $6,600,000 $6,000
Severity trend:
= ($6,000 / $5,000)^(1/2) - 1
= 1.0954 - 1 = 9.5% annually
```
## Factors Affecting Severity
### Inflation
- Medical costs
- Repair costs
- Wage inflation
- General price levels
### Social/Legal
- Jury awards increasing
- Attorney involvement
- Regulatory changes
- Coverage interpretations
### Mix of Business
- Higher/lower limits
- Different territories
- Industry changes
- Exposure mix
## Related Concepts
- [[Frequency Analysis#Definition]]
- [[Frequency-Severity Method#Definition]]
- [[Loss Trend#Definition]]
## References
- Friedland, Chapter 8
- Werner & Modlin, Chapter 8