Brosius Flashcards
Advantage of Least Squares method
flexibility to include link ratio and budgeted loss methods as special cases
Disadvantages of Least Squares methodology (2)
- sampling error can lead to values of a and b that don’t make sense
- significantly impacted by systematic changes in loss experience and must be adjusted before using
Best use for Least Squares methodology
significant random fluctuations
Least Squares formulas (3)
L(x) = a + bx b = [ avg(xy) - avg(x) * avg(y) ] / [ avg(x^2) - avg(x) ^2 ]
Explanation of graphs for least squares, link ratio, and budgeted loss methods (3)
least squares - line w/intercept
link ratio - straight line through origin
budget loss - horizontal line
Advantages of the Least Squares method over a pure Bayesian estimate (3)
- simpler to compute
- easier to explain
- less dependent on underlying distribution
Development formula for Least Squares and ratio results
L(x) = (x - E[X]) * [ covariance(X,Y) / var(X) ] + E[Y]
if ratio = 1»_space; BF
if ratio < 1»_space; budgeted loss
if ratio > 1»_space; link ratio
Credibility form of Least Squares development formula
L(x) = Z * (x / d) + (1 - Z) * E[Y]
where Z = bd = b / c if using Least Squares
where Z = VHM / (VHM + EVPV) w/large systematic distortions
and x / d = link ratio estimate w/ d = % emerged
Variability represented by VHM and EVPV
VHM = variability from loss occurrence process -- blame UW EVPV = variability from loss reporting process -- blame claims
VHM formula
VHM = d^2 x sigma(Y)^2
EVPV formula
EVPV = sigma(d)^2 x ( sigma(Y)^2 + (EY)^2)
When to use the credibility form of the development formula
when systematic distributions are too large to be corrected for
Potential reserve adjustments to a higher percent reported (3 + justification)
- Decrease the reserve by a corresponding amount (BL) - appropriate with speedup in reporting
- Leave the reserve as a % of expected loss (BF) - appropriate if a random large loss drives higher % reported
- Increase the reserve by a corresponding amount (CL) - appropriate with low confidence in expected loss estimate
Interpretation of Cov(X,Y) / Var(X) ratio in the development formula
If ratio is < 1, means that the ultimate loss increases at a slower pace than the increase in reported losses
Caseload effect and formula
d can be dependent on Y and Least Squares still works
if for small y, claims are reported more quickly, therefore d is larger for small y.
similarly if there is a large weather event, y is large and many claims are reported quickly, d will also be large
L(x) = Z * (x - x-not) / d + (1 - Z)*E[Y]
where E[X | Y] = d + x-not / y
and Z = VHM / (VHM + EVPV)