Risk aversion and asset prices

Transcription

Risk aversion and asset prices
er.
if
O#ad,
on informzei availabie 23~the
ion operator mnditional
jht tith cm-refit consumption c,,
to comb
to compute utility at P, i.e.,
is specified as the CES form
?VhYWiX,
(c, z) =
[cp+ zyp,
c,zlO,
O#p<l,
Oqkl.
(4
us utility is defined recursively by
Q=
t2 o.
[c/‘+
P(Etv+l)P’a]l’p,
(3)
a
%is
czi
W
=
H
st-+
,t+B
”
.
s
--k
9
9
W
(a---
cave
ce
is
190
L 6. Epstein, Ri; k aversionand assetprices
comparative risk aversion analysis
change in prices is ambiguous if u
cas.
the issue of the circumstances u
artingale property. It is well
generally not a feature of
states ‘that the presence of
for current consumption is inconsistent
odel, even with 8,‘s correlated
see from (20) that only if a = p = 1 do we obtain the simple
discounting formulae
P(s,) = Bhh +PwL
erfect intertemporal substitutability (a = ao) and risk neutrality
( a = 1) are necessary for these relations to be valid.
f(0) > 0 ) f(co). Thus 3y* > 0, f( y*) = 0.
hus y* is the unique zero of f.
Step 2: Show that (22) possesses a unique solution. It suffices to prove
existence and uniqueness of
n_l
solving fqKi)=O, j=l,...,
(
&.l)p+ K*pqa-P)‘P
1
a soWion
(Si+pi(s))](p-l)‘p,
which is a form of ‘converse’ for (1
From (11)
,A(S)P/o-P)=
for some constant
derive
l+
3(
Substitute the latter equation into ( 03) and (10) to
192
LG. Epstein, Risk aversionand assetprices
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: The case of homogeneous
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aeo. (
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