18
We use dummy variables rather than an import price or energy price measure because we
believe that these were atypical events that had atypical effects on the economy.
35
last quarter of 1999, though we vary the end date in some specifications to check the extent to
which our results depend on the experience of the 1990s. Data sources and the specification of
the dummy variables for price controls and oil shocks can be found in the appendix.
18
All the
parameters of the model were estimated simultaneously by non-linear least squares.
Results
Table 2 presents results for four different estimates with five types of variation: in the
dependent variable, in the method of constructing
%
e
and
%
L
, in the unemployment measure and
its lags, in the sample period and in the inclusion of the term for nominal rigidity.
Table 2
Estimated Parameters for Near Rational Phillips Curve
(standard errors in parenthesis)
Independent Variables and
Characteristics
Dependent Variable
CPI
GDP deflator
PCE deflator
Compensation
Index-prod.
growth
Constant
.042
(.009)
.028
(.008)
.024
(.011)
.017
(.003)
Unemployment
-.54
(.12)
-.45
(.12)
-.40
(.16)
-.39
(.07)
D (Constant in coefficient
on expectations)
-.70
(.39)
-.88
(.45)
-.23
(.47)
-.32
(.22)
E (Coefficient of
%
L
2
in
coef on expectations)
601
(180)
2824
(1119)
1210
(552)
1311
(355)
Standard deviation of
desired wage change from
term for nominal rigidity
term not
included
term not
included
.020
(.013)
term not
included
Method for constructing
%
L
geometric
16q MA
(equal
geometric
linear
36
weights)
Method for constructing
%
e
SCF
12 unrestricted
lags
geometric
Livingston
Unemployment measure
and number of lags
Total
0 lags
Total
11 lags
Shimer
7 lags
Male
3 lags
Sample Period
54:1-89:4
54:1-99:4
54:1-99:4
54:1-99:4
Natural Rate
7.7
6.4
6.1
4.3
Optimal Rate of Inflation
3.2
1.6
2.3
2.0
Lowest Sustainable Rate of
Unemployment
4.6
4.4
4.6
2.2
Durbin-Watson Statistic
1.4
2.0
1.9
1.1
R
2
.792
.698
.707
.764
Our first focus of attention is the estimated value of the cumulative normal multiplying
inflationary expectations when inflation is zero. In the theoretical model this corresponds to the
fraction of firms behaving in a fully rational fashion at zero inflation. The model predicts that this
fraction will be less than unity, and also that as inflation increases above zero, the fraction of
rational firms will rise. Both of these predictions yield tests of the model.
The NAIRU specification for the Phillips curve is nested in our model and can be obtained
if the value of D is sufficiently high. For example, if D were 2 or higher the coefficient on
inflationary expectations would never fall below .97 and there would be little room for changing
experience with inflation to affect the coefficient on inflationary expectations. All of the four
estimated values of D imply coefficients on expected inflation less than .5 at zero inflation. The
lowest implies a coefficient of .19. In all four cases a value of D which would imply a coefficient
of .9 or greater (1.28) can be rejected at conventional levels of significance.
The instantaneous effect of increasing inflation above zero can be computed as one minus
37
the cumulative normal evaluated at D divided by the sum of the coefficients on unemployment
and its lags. Those values are about -1.5 or larger (in absolute value) in the specifications
presented here. Thus to a first-order approximation raising inflation from zero to one percent will
cause a reduction in unemployment of 1.5 percentage points or more.
The term which most distinguishes our model from that of the textbooks is the coefficient
of the square of lagged inflation in the cumulative normal multiplying inflationary expectations
(E). If E is zero, the coefficient on expectations will not vary with past rates of inflation. Our
theory says it should and that is what we find in each of the specifications we have estimated. In
all four specifications presented above E is large, and more than twice its estimated standard error.
Going from zero to five percent inflation would increase the argument of the cumulative normal
by 1.5 to 7.1 depending on the specification. Except with CPI inflation as the dependent variable,
the coefficient on inflationary expectations is above .95 by the time inflation has reached 4
percent. For the CPI-specification the coefficient is .6 at 4 percent inflation and rises above .95 at
about 6.5 percent.
Besides allowing us to estimate the effect of inflation on the use of inflationary
expectations, estimating our model also allows us to calculate an optimal rate of inflation and the
potential employment gains of moving to that optimum. We have computed the optimal rate of
inflation for the four models in table 2 from the estimated parameters numerically. We have also
computed the natural rate in each model and the Lowest Sustainable Rate of Unemployment or
LSRU—the unemployment rate at the optimal rate of inflation. The optimal rate of inflation
ranges from 1.6 percent to 3.2 percent. The difference between the natural rate and the LSRU
ranges from 1.5 to 3.1 percentage points. Figures 7 a,b,c, and d show the long-run relationship