More Workers Comp - earned prem & parallelogram method

MILLER Kathleen C ( Kathleen.C.MILLER@state.or.us )
27 Feb 1998 16:39:04 -0800

In showing the parallelogram method, pages 27 and 28 use index factors
relative to the oldest rates, apply them to relevant areas, develop an avg
index, and divide it into the current index to find the adjustment factor.
Well, somewhere along the way I learned to do this from the opposite
perspective. I develop "to current factors" for each area and calc an
average, weighted by earnings percentage, for the adjustment factor.
For me, it seems easier to do. Unfortunately, I always seem to be off the
book's calcs by about 0.001

Of course my firsts thoughts are rounding error, and what are the
chances of a multiple choice question where it makes a difference?
Then my thoughts say "very likely." Then I think, gee if it's essay, will
they even recognize what I'm doing? What do ya think? And then, what
if they preface it with an " as per the method shown in Feldblum's
article?" Will it just be wrong regardless of the answer? And
then,..EGADS! What if they say it must be performed with a pencil held
between your left toes at a 35 degree angle? <It could happen.>

Below is my logic that parallels the books example pages 27-28. See if
you can find a flaw that might lead to the slightly different answer. I'd like
to know even if I can't do it in the exam.

area ( earnings%) to current factor product
iv (.094) (.92)(1.15)(1.1) = 1.1638 .1094
v (.031) (1.15)(1.1) = 1.265 .0392
ix & vi (.156) (.92)(1.1) = 1.012 .1579
vii & viii (.719) (1.1) = 1.1 .7909
total 1.0974

For example, in order for region iv to be brought to current rates, we
must apply the 8% decrease in April, the 15% policy increase in July, and
the 10% increase in January of '93. Hence the (.92)(1.15)(1.1).

The book answer is 1.096 instead of 1.097. IF it was just this once, I
would ignore it, but I'm consistently off by a similar amount. Maybe, just
maybe, there's a reason that it has to be done the other way.