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Federal Reserve Bank of Dallas

Economic
& Financial

PolicyReview
Volume 1, Number 6, 2002

Using the Purchasing Managers’ Index
to Assess the Economy’s Strength
and the Likely Direction of Monetary Policy
Evan F. Koenig

When economists are concerned that the economy may be about to
change direction, one of the indicators to which they give special scrutiny is
the Purchasing Managers’ Index (PMI), released monthly by the Institute for
Supply Management. This article discusses the construction and interpretation of the PMI and presents evidence of its usefulness as an indicator of
growth in the manufacturing sector and the economy as a whole, and as a
predictor of changes in Federal Reserve policy. PMI values above 47 generally signal expansion in manufacturing, while the critical value for positive
GDP growth is around 40. Over the past fifteen years, PMI values above
52.5 have tended to be associated with rising short-term interest rates.
Koenig is a vice president and senior economist in the Research
Department of the Federal Reserve Bank of Dallas.
Suggested Citation
Koenig, Evan F. (2002), “Using the Purchasing Managers’ Index to Assess
the Economy’s Strength and the Likely Direction of Monetary Policy,”
Federal Reserve Bank of Dallas Economic and Financial Policy Review,
Vol. 1, No. 6, http://dallasfedreview.org/pdfs/v01_n06_a01.pdf.

Economic & Financial Policy Review is published by the Federal Reserve Bank of Dallas. The views expressed are those of the authors and
should not be attributed to the Federal Reserve Bank of Dallas or the Federal Reserve System. Articles may be reprinted on the condition that
the source is credited and the Federal Reserve Bank of Dallas is provided a copy of the publication or a URL of the web site containing the
reprinted material. For permission to reprint or post an article, e-mail the Public Affairs Department at dal.webmaster@dal.frb.org.

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ach month, the Institute for Supply Management (ISM) sends a questionnaire on business conditions to purchasing and supply executives
in manufacturing firms across the country. Responses to several of
the survey questions are combined to form the Purchasing Managers’
Index (PMI). As a forecasting tool, the PMI has several attractive features.
Chief among them is its timeliness. The PMI for a given month is released
on the first business day of the following month and often provides the earliest reading on changes in the economy’s strength. Its main rival in this
regard is the Labor Department’s payroll employment report, which is
released on the first Friday of each month and contains data for the prior
month. Unlike the PMI, the employment report covers all sectors of the
economy. However, it misses the information on sales (orders) and production captured by the PMI. (The Federal Reserve’s report on industrial
production and the Department of Commerce’s report on manufacturers’
orders and shipments become available approximately two and four
weeks, respectively, after the PMI.
In addition to timeliness, the PMI has the advantage that it is not subject to large revisions. Indeed, the only revisions to the PMI are annual
updates to seasonal adjustment factors, which are generally small enough
that they can be ignored. The lack of significant revisions is important
because to achieve optimal performance from a forecasting model, it is
essential that the model be estimated using “real-time-vintage” right-handside data — data at each point in the sample that would have been available at that time. Using real-time-vintage data at the estimation stage is
critical because it is almost always these data that are ultimately plugged
into the estimated equation to produce a forecast (Koenig, Dolmas, and
Piger, forthcoming). For many economic time series, gathering these realtime-vintage data is a daunting task.
On the negative side of the ledger, the ISM survey incorporates only
information available to corporate executives in the first half of the survey
month. If a shock hits the manufacturing sector in the second half of the
month, it will not be reflected in the PMI until the following month’s survey
is compiled and published. Of course, this limitation is hardly unique to the
PMI. The payroll employment report, for example, captures only workers
who are on firms’ payrolls during the pay period that includes the 12th of
the month.
Another potential limitation of the PMI arises from the fact that it —
unlike the employment release — is a diffusion index: A high PMI reading
simply means that more executives are reporting improving business conditions than are reporting deteriorating business conditions. There is no
attempt to capture differences across firms or over time in the intensity
with which conditions are changing. Nor are the responses of different
firms weighted by firm size. It follows that the PMI may miss a shift in the
direction of the overall economy if that shift happens to be concentrated in
a relatively small number of large firms.
I begin by providing background information on the ISM survey and
the PMI, including a description of who participates in the survey, the
survey’s timing, and how the PMI is constructed. Next, I discuss the
usefulness of the PMI as an early signal of changes in manufacturing
output and gross domestic product (GDP). The evidence suggests that
the PMI captures information about GDP growth beyond that contained
in the Federal Reserve’s report on industrial production and official government reports on employment and retail sales. Given these results,
it may come as no surprise that the PMI is a strong predictor of changes

E

VOLUME 1, NUMBER 6, 2002

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in monetary policy, as measured by the Federal Reserve’s federal-fundsrate target.
PMI BACKGROUND1
Basics
The ISM (formerly known as the NAPM, or National Association of
Purchasing Management) has conducted its survey of purchasing and
supply executives continuously since the end of World War II. The
survey goes out to executives representing more than 400 companies in
twenty manufacturing industries spread across all fifty states.2 These executives are asked about new orders their firms have received and about
their firms’ production, employment, inventories, order backlogs, new export
orders, and imports of materials and supplies. In each case, executives
are asked whether the variable’s current level is higher (or better), lower
(or worse), or the same as during the preceding month. To the percentage
of executives who report higher levels of a variable is added half the percentage who report an unchanged level to create a diffusion index for that
variable. Thus, an index reading above 50 indicates that more executives
are reporting better values for a variable than are reporting worse values.
The higher the index reading, the greater the preponderance of positive
responses. Executives are also asked whether their customers’ inventories
are too high, too low, or about right; whether supplier deliveries are slower,
faster, or about the same as during the prior month; and whether suppliers
are charging prices that are higher, lower, or about the same. Diffusion
indexes for customer inventories and prices paid are constructed in much
the same way as those for new orders, production, and so forth already
discussed. In contrast, the supplier-deliveries index is higher if a greater preponderance of executives report slower supplier deliveries. Each index is
adjusted for normal seasonal variation.
The PMI combines the information in the New Orders (30 percent
weight), Production (25 percent weight), Employment (20 percent weight),
Supplier Deliveries (15 percent weight), and Inventories (10 percent
weight) indexes. According to the ISM, a PMI reading above 50 indicates
that the manufacturing sector of the economy is generally expanding, and
a reading above 42.7 indicates that real GDP is expanding. (These rules
of thumb are updated below.) Figure 1 shows a plot of the PMI from
January 1948 through June 2002. Clearly, there is a close (though imperfect) correspondence between periods in which the PMI is low and periods
in which the National Bureau of Economic Research (NBER) has determined that the economy was in recession (the shaded bars).3

VOLUME 1, NUMBER 6, 2002

1

This section draws on information from the ISM web site (www.napm.org) and from
Rogers (1998).

2

The twenty industries are Food; Tobacco; Textiles; Apparel; Wood and Wood Products;
Furniture; Paper; Printing and Publishing; Chemicals; Petroleum; Rubber and Plastic
Products; Leather; Glass, Stone, and Aggregate; Primary Metals; Fabricated Metals;
Industrial and Commercial Equipment and Computers; Electronic Components and
Equipment; Transportation and Equipment; Instruments and Photographic Equipment; and
Miscellaneous. An effort is made to survey executives from a representative cross section
of these industries. In total, the ISM has nearly 50,000 members.

3

The NBER has yet to announce an ending date for the most recent recession. Figure 1
assumes that December 2001 will eventually be declared the trough month.

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Other Purchasing Managers’ Surveys and Indexes
Besides the ISM national survey of executives in the manufacturing
sector, there are numerous local purchasing managers’ surveys and indexes
and a national survey of purchasing executives in nonmanufacturing firms.
Local indexes are meant to track the ups and downs of particular cities’
economies. They are constructed by local ISM affiliates using a methodology similar to that used for the national PMI. The Purchasing Management Association of Chicago, for example, publishes an index that receives considerable attention because of its timing (it is released prior to
the national PMI) and because of the number of major manufacturing firms
with offices in Chicago. Within the Eleventh Federal Reserve District, there
is a Dallas/Fort Worth purchasing managers’ index (begun in 1999) and a
Houston index (begun in 1995). The surveys upon which the local indexes
are based are conducted independently of the national survey and play no
role in the construction of the national PMI.
The manufacturing sector of the economy is much more cyclical than
the service-producing sector but accounts for ever-shrinking shares of
total employment and spending.4 To achieve more complete coverage of
the economy, the ISM has begun a monthly survey of purchasing managers outside the manufacturing sector. Results from this survey are
released a few days after release of those for the manufacturing sector.
Unfortunately, at five years, the track record of the new survey is too short
to properly evaluate. Moreover, there is no weighted composite index for
the nonmanufacturing sector like there is for the manufacturing sector.
Accordingly, this article focuses exclusively on the national PMI.
THE PMI AS A TOOL FOR FORECASTING OUTPUT GROWTH
The timeliness and convenience of the PMI don’t count for much if
the index doesn’t contain useful information on the economy — especially
information beyond that captured by other published data series. This secFigure 1

ISM’s Purchasing Managers’ Index
Index
80

70

60

50

40

30

20
’50

’55

’60

’65

’70

’75

’80

’85

’90

’95

’00

NOTE: Shaded areas indicate recessions.
SOURCE: Institute for Supply Management.
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VOLUME 1, NUMBER 6, 2002

The share of manufacturing output in nominal GDP fell from 27.0 percent in 1960 to 21.0
percent in 1980 to 15.9 percent in 2000. Over the same period, the share of manufacturing employment in total employment dropped from 31.0 percent to 22.4 percent to 14.0
percent.

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tion presents evidence of the PMI’s ability to predict changes in manufacturing output and real GDP. The marginal predictive power of the PMI for
GDP growth is given special attention for two reasons. First, the usefulness of the PMI for predicting changes in manufacturing output has
already been established (Harris 1991, Rogers 1992). Second, however
strongly the PMI may be related to factory output, the manufacturing sector’s diminishing relative size raises the legitimate concern that the PMI
may have become irrelevant for predicting changes in the strength of the
economy as a whole.
Simple Forecasting Relationships
A regression of manufacturing output growth on the PMI yields the
following results:
∆q = 0.70 (pmi – 47.77) + 0.84 ∆pmi
(0.13)
(0.80) (0.11)

R 2 = 0.650
S.E. = 5.69

over a sample period running from second quarter 1948 through second
quarter 2002. Here, ∆q is the within-quarter annualized percentage growth
rate of manufacturing output, as measured by the Federal Reserve Board;
pmi is the quarterly average value of the PMI; and ∆pmi is the change in
the PMI’s quarterly average value.5 Standard errors are in parentheses.6
According to these results, factory output growth depends about equally
on the level of the PMI and the PMI’s most recent change. A 1-point
permanent increase in the PMI implies an immediate 0.70 + 0.84 = 1.54percentage-point increase in annualized factory output growth, but only a
0.70-percentage-point increase in subsequent quarters. The critical value
for the PMI — the reading that is consistent with a stagnant manufacturing
sector — is significantly less than 50.7
The relationship between the PMI and real GDP growth is similar to,
but not quite as tight as, that between the PMI and output growth in the
manufacturing sector:
∆y = 0.28 (pmi – 40.85) + 0.29 ∆pmi
(0.06)
(1.42) (0.07)

R 2 = 0.466
S.E. = 3.01

The sample period runs from third quarter 1948 through first quarter 2002,
∆y denotes the annualized quarterly growth rate of real GDP, and pmi is
5

VOLUME 1, NUMBER 6, 2002

More precisely, ∆q (t ) ≡ 400[q (t, 3) – q (t – 1, 3)] where q (t, i ) is the logarithm of manufacturing output in the i th month of quarter t. Both here and in similar regressions reported
below, I use current-vintage output growth as the dependent variable. Presumably, the
most up-to-date available estimates of output growth are the most accurate, and it is the
most accurate measure of growth that the forecaster will want to predict. Even so, there is
an advantage to using early estimates of growth as the dependent variable for regression
purposes if these growth estimates are efficient — that is, if revisions to the early releases
are unpredictable using information available at the time. Unfortunately, early estimates of
output growth are not readily available over the full sample period used here. Moreover,
early estimates of industrial production growth (which might be expected to have properties similar to those of early estimates of manufacturing output growth) are inefficient
predictors of subsequent releases. (The evidence for early GDP growth estimates is more
favorable to the efficiency hypothesis, but, again, available data are limited.) For a more
complete discussion of when estimation using early-release data is appropriate, see
Koenig, Dolmas, and Piger (forthcoming).

6

Here and elsewhere in this article, standard errors are corrected for possible
heteroskedasticity and serial correlation.

7

Harris (1991) and Rogers (1992) report similar results.

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now a weighted average of PMI levels this quarter and last quarter.8 For
GDP growth the critical value of the PMI is about 41, according to these
results. A sustained, 1-point increase in the PMI signals a 0.28 + 0.29 =
0.57-percentage-point increase in GDP growth in the first quarter in which
it hits and a 0.28-percentage-point increase thereafter.
Output growth became substantially less volatile beginning in the mid1980s (McConnell and Perez-Quiros 2000). The forces responsible for this
change may have also altered the relationship between the PMI and output
growth. When the PMI – factory-output-growth relationship is reestimated
over a sample period that starts in fourth quarter 1983, the following
results are obtained:
∆q = 0.61 (pmi – 46.58) + 0.09 ∆pmi
R 2 = 0.454
(0.18)
(1.60) (0.12)
S.E. = 3.25
Similarly, the PMI – GDP-growth relationship becomes
∆y = 0.27 (pmi – 39.58) + 0.06 ∆pmi
(0.09)
(2.95) (0.08)

R 2 = 0.329
S.E. = 1.86

In both cases, the critical value of the PMI is not significantly different from
the value estimated over the full sample. The long-run impact of a 1-point
increase in the PMI is also essentially the same as before: 0.61 percentage points for manufacturing output growth and 0.27 percentage points for
real GDP growth. However, in each case the coefficient of the ∆pmi term
is small in magnitude and statistically insignificant, indicating that the
short-run impact of a PMI change is now the same as its long-run impact.
Hence, forecasting output growth using the PMI has become simpler over
time. (For speculation on the underlying causes of the change in the
PMI – output-growth relationship, see the box on page 7 titled “Why Have
the Links Between the PMI and Output Growth Changed?”)
Figure 2 gives an informal sense of how well the PMI has served to signal changes in output growth in recent years. It shows a plot of the threeFigure 2

PMI Captures Trends in Factory Output Growth
Index

Percent per year

77

18

72

15

67

12

62

9

57

6

52

3

47

0
–3

42
Factory output
(annualized three-month growth)
PMI (three-month average)

37
32

–6
–9
–12

27
’84

’85

’86

’87

’88

’89

’90

’91

’92

’93

’94

’95

’96

’97

’98

’99

’00

’01

’02

SOURCES: Institute for Supply Management; Federal Reserve Board.

8

VOLUME 1, NUMBER 6, 2002

Specifically, pmi (t ) ≡ (1/9)PMI(t – 1, 2) + (2/9)PMI(t – 1, 3) + (3/9)PMI(t, 1) + (2/9)PMI(t, 2)
+ (1/9)PMI(t, 3), where PMI(t, i ) is the level of the PMI in the i th month of quarter t. This
weighted-average definition is appropriate given that GDP growth measures the percent
change in the quarterly average level of economic activity.

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month annualized percent change in manufacturing output along with a
three-month average of the PMI from December 1983 to June 2002 (the same
period covered by the regression results above). The chart is constructed so
that zero factory output growth lines up with a PMI reading of 47 (which
approximates the estimated critical value over the interval displayed). Note
how the PMI captures sustained movements in output growth while smoothing out much of the short-term “noise.” This filtering effect is an additional
attractive feature of the PMI, relative to direct measures of output growth.
Evidence of Marginal Predictive Power for GDP Growth
As mentioned above, the Labor Department’s employment report is
released on about the same schedule as the PMI and provides an alternative early source of information on GDP growth. Retail sales and industrial
production reports are released with a longer lag than employment and the
PMI, but still early enough that they too can be used to forecast GDP. (The
first official estimate of each quarter’s GDP isn’t released until a full month
after the end of the quarter.) By putting jobs, sales, and industrial production data together with the PMI on the right-hand side of a regression equation that has GDP growth as its dependent variable, it’s possible to determine whether the PMI has any predictive power beyond these measures of
economic activity. To make this test a fair one, it is important that only the
relatively early jobs, sales, and production data that would have been available to a forecaster in real time be included in the regression.

Why Have the Links Between
the PMI and Output Growth Changed?
As noted in the main text, the change in the PMI seems to be every bit as important as the level of the PMI for predicting output growth over much of the post – WorldWar II period. Over the past twenty-odd years, however, the predictive power of PMI
changes disappears. Equivalently, during the 1950s, 1960s, and 1970s, the PMI initially
underresponded to changes in the rate of output growth. No such temporary underresponse is evident from the mid-1980s on.
One possible explanation for the changed relationship between the PMI and output growth centers on the behavior of materials inventories and the fact that
the PMI includes, as one of its components, the ISM’s Inventories Index. If an expansion of output is initially accompanied by a drawdown of materials inventories, then the
Inventories Index will drop even as other PMI components (New Orders, Production,
Employment, and Supplier Deliveries) signal expansion by rising. Hence, the Inventories Index initially acts as a restraining force on the PMI. It exerts a similar temporary restraining force in the opposite direction if output suddenly contracts.1 Note that
these effects are smaller the more tightly firms control their inventories. Tighter inventory controls are sometimes cited as an important contributor to the greater stability of
output growth in the period since 1983 (McConnell and Perez-Quiros 2000).
A second explanation centers on the fact that the ISM has tended to oversample
large, well-established firms. This sampling bias means that insofar as newer, smaller
firms are relatively quick to adjust their production to shifts in demand, the PMI initially
underestimates changes in output growth. Of course, the distortion shrinks if the agility
differential between small and large firms narrows or if the ISM makes its survey sample
more representative. There are reasons to suspect that both of these changes have
occurred. For example, the ISM has expanded the size of its sample: Executives at
nearly 400 firms are included in the ISM survey today, compared with 300 firms in the
early 1990s and about 225 firms in the early 1980s (Harris 1991; www.napm.org). The
greater responsiveness of production to demand has been widely noted in the business press and in the public testimony of policymakers (Greenspan 2002).

NOTE
1

VOLUME 1, NUMBER 6, 2002

Consistent with this story, movements in the ISM Inventories index lag movements in the
PMI by about two months.

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Table 1 presents results from two sets of such real-time forecasting
regressions. The first set predicts quarterly GDP growth using employment, retail sales, and industrial production data that would have been
available within the first week of the close of the quarter, along with the two
most recent months’ PMI observations.9 The second set uses data that
would have been available within three weeks of the close of the quarter.
These data include one additional month of retail sales and industrial production data and an additional round of revisions to the retail sales and
industrial production data for earlier months. The table includes measures
of each equation’s fit, along with the coefficients of the PMI terms (and
their standard errors).
Several conclusions jump out from Table 1. First, real-time monthly
jobs, sales, and factory output growth are all highly useful predictors of
GDP growth. Second, there is nothing to be gained by waiting an extra two
weeks to get a complete set of retail sales and industrial production data
for a given quarter: In Table 1, the R 2 using data set 2 is nearly the same
as that using data set 1. Third, even with complete monthly jobs, sales, and
factory output data, recent PMI observations have predictive power for
GDP. Finally, it is the month-to-month change in the PMI that has marginal
predictive power rather than the level of the PMI: The lagged PMI term has
a coefficient equal in magnitude and opposite in sign to the most recent
month’s PMI. This finding suggests that the PMI detects end-of-quarter
growth speedups and slowdowns that show up in the GDP statistics but
are missed by initial jobs, sales, and industrial production estimates.10
Table 1

Forecasting GDP Growth: Does the PMI Have Real-Time Marginal
Predictive Power? (1980:1–2002:1)
Coefficient
(standard error)

Marginal significance level
Data set 1:

Data set 2:

R2

S.E.

Jobs growth

Sales growth

IP growth*

PMI

Lagged PMI

.764

1.53

.001

.002

.000

.26
(.09)

–.23
(.10)

.767

1.52

.000

.001

.000

.26†
(.09)

–.26†
(.09)

.766

1.52

.005

.006

.000

.22
(.10)

–.19
(.11)

.768

1.52

.000

.004

.000

.21†
(.10)

–.21†
(.10)

* IP is industrial production.
† PMI and lagged PMI coefficients constrained to be equal in magnitude and opposite in sign.

VOLUME 1, NUMBER 6, 2002

9

Because quarter-t GDP growth measures the percent change in the quarterly average
level of economic activity between quarters t and t – 1, monthly growth rates of employment, sales, and industrial production extending back to the second month of quarter
t – 1 are potentially informative. Table 1 lag lengths are chosen accordingly. However,
only the two most recent monthly PMI readings were included in the reported regressions
after preliminary tests established that additional PMI readings contain no significant
marginal information.

10

In regressions similar to those reported in Table 1, the New Orders and Production components of the PMI did not perform as well as the PMI itself. Although the conventional
wisdom is that movements in orders lead movements in production, the ISM New Orders
Index does not systematically lead either the ISM Production Index or the PMI.

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The Bottom Line
The Purchasing Managers’ Index deserves the attention it receives in
the financial and business press as an indicator of changes in real economic
activity. If the index is considered in isolation, its level is what matters. In
recent years, PMI readings above 47 have signaled an expanding manufacturing sector (with each point above 47 translating into about 0.6 percentage
points of factory output growth), and PMI readings above 40 have signaled
an expanding economy overall (with each point above 40 translating into
about 0.25 percentage points of GDP growth). If the index is considered in
conjunction with recent jobs, sales, and factory output data, its change
embodies useful information. A rising PMI signals that GDP growth is likely
stronger than early estimates of these other indicators would suggest.
THE PMI AND MONETARY POLICY
The Federal Reserve’s Federal Open Market Committee (FOMC) uses
the interest rate on overnight loans of bank reserves, the federal funds rate,
as its policy instrument. Eight times each year, the FOMC meets to pick a
target level for the funds rate. Occasionally, the target rate is changed
between regularly scheduled FOMC meetings, either at the discretion of the
Chairman of the FOMC (currently Alan Greenspan) or following a telephone
conference call. Studies of its decisionmaking suggest that the FOMC tends
to raise the target funds rate when inflation is high or threatens to increase,
as signaled by labor and output markets that either are currently tight or seem
likely to become tight as a result of unsustainably rapid growth in employment
or output (McNees 1986, 1992; Taylor 1993). Conversely, the FOMC tends to
lower the target funds rate when inflation is low or threatens to fall as a result
of current slack in the labor and output markets, or as a result of subpar employment or output growth. Since the PMI appears to have marginal predictive
power for changes in real economic activity, one might expect it to serve as a
useful early signal of changes in Federal Reserve policy. This section presents
evidence that over the past fifteen years, such, indeed, has been the case.
Evidence of the PMI’s Predictive Power
Prima facie evidence of a connection between the PMI and monetary
policy is presented in Figure 3, which shows monthly values of the PMI
Figure 3

PMI Highly Correlated with Monetary Policy Decisions
Index

Percentage points

70

2
PMI

Federal funds rate
(three-month change, centered)

65

1.5
1

60

.5
55
0
50
–.5
45

–1

40
35

–1.5

’88

’89

’90

’91

’92

’93

’94

’95

’96

’97

’98

’99

’00

’01

’02

–2

SOURCES: Institute for Supply Management; Federal Reserve Board.

VOLUME 1, NUMBER 6, 2002

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along with the centered three-month change in the target federal funds
rate set by the FOMC. The correlation between the two series is high (0.76
over the full sample and 0.87 over the past four and a half years). Typically,
the FOMC has raised the funds rate when the PMI registers above 52.5
and lowered the funds rate when the PMI registers below 52.5. Of course,
the FOMC may not be responding to the PMI at all, but to information from
entirely different sources that moves similarly to the PMI.11
In any case, the relationship shown in Figure 3 is coincident, not predictive. Testing the PMI’s usefulness for forecasting monetary policy requires
including the PMI — along with measures of inflation, economic slack, and
real growth — as a right-hand-side variable in a regression explaining future
changes in the FOMC’s target funds rate. The use of real-time-vintage data
is critical, just as it was in our earlier GDP forecasting exercises. The analyst
who estimates funds-rate equations that include data that would have been
unavailable to policymakers can easily draw incorrect conclusions about
FOMC behavior (Orphanides 2001) and will find that the equations do a
poor job of forecasting future funds-rate changes.12
The regression equation estimated here takes the form ff – ff –i =
α( ff *–i – ff –i ), where ff is the end-of-month target funds rate and ff * is a
long-run target rate toward which the FOMC gradually moves. This longrun target rate is a function of inflation (π), labor-market slack as measured
by the unemployment rate (u), recent jobs growth (∆e), and the most
recent PMI (pmi ):
ff * = α0 + α1π + α2u + α3∆e + α4pmi.
The coefficients α1, α2, α3, and α4 measure the funds rate’s eventual response to a 1-percentage-point increase in each of its determinants. Some
economists have argued that α1 must be greater than 1 if monetary policy
is to be stabilizing: Only if α1 > 1 will the real federal funds rate ( ff – π) rise
in response to high inflation and economic conditions that tend to increase
inflation over time, and it takes an increase in the real funds rate to choke
off excess aggregate demand (Clarida, Gali, and Gertler 2000). The larger
is α, the more quickly the funds rate responds to changes in its determinants. All data used in the funds-rate regression are real time.13

VOLUME 1, NUMBER 6, 2002

11

Federal Reserve Bank directors are one such source. Another is the Federal Reserve’s
own Beige Book survey. For a description of the Beige Book and documentation of its
usefulness as a forecasting tool, see Balke and Petersen (2002).

12

The Scylla to this Charybdis is to exclude from the regression some variable that policymakers relied on in reaching their decisions. Again, the analyst may draw inappropriate
conclusions about policymakers’ behavior (Lansing 2002). However, left-out-variable
error does not result in systematically biased out-of-sample forecasts.

13

Employment growth is measured by 200 times the six-month change in the logarithm of nonfarm employment. Measuring the employment change over a shorter period did not substantially alter results. Inflation is measured by the twelve-month percentage change in the
core Consumer Price Index (CPI) from the beginning of the sample period through December
1995. CPI inflation data are not revised. From December 1999 through the end of the sample,
inflation is measured by real-time official estimates of the four-quarter percentage change
in the core Personal Consumption Expenditures (PCE) Price Index (with correction for
September 11 insurance distortions). During 1996 – 99, inflation is measured by a weighted
average of core CPI and real-time core PCE inflation rates, with a gradually falling weight on
CPI inflation and a gradually increasing weight on PCE inflation. Fed policymakers’ increasing attention to PCE inflation at the expense of CPI inflation is evident in Greenspan’s
semiannual reports to the Congress during the late 1990s. The constant term, α0, in the
regression equation was allowed to shift gradually along with the weighting between the
CPI and PCE inflation measures. Results change little when the core CPI inflation measure
is used over the full sample and α0 is held fixed.

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The sample period starts in January 1988, a few months after Greenspan
began his first term as Chairman of the FOMC.14
Results for i = 3 are reported in Table 2. (Results for values ranging
from i = 2 to i = 8 are similar.) As expected, the FOMC gradually raises its
federal funds rate target when inflation is high, unemployment is low, or
employment growth is rapid. The funds rate’s long-run response to inflation
is more than 1-for-1, but barely. The PMI is also a strong predictor of fundsrate changes. Other things constant, a 5-point increase in the PMI translates into a 25-basis-point higher federal-funds-rate target three months
hence and ultimately a 100-basis-point increase.15
Figure 4 shows a plot of the actual target funds rate, ff , along with
estimates of ff *. If the funds-rate equation is a good description of policymakers’ behavior, the FOMC’s funds-rate target ought to be increasing
when ff < ff * and decreasing when ff > ff *. This prediction is borne out.
The PMI, Federal Reserve Policy and the 2001 Recession
How well does the simple funds-rate model developed above predict
the FOMC’s policy actions during the past two and a half years? How
important is the PMI to understanding the FOMC’s behavior during the
transition from economic expansion to recession? To answer these questions, I begin by estimating the funds-rate model described above using
only data that would have been available at the close of 1999. Holding these coefficients fixed, I then substitute actual (real-time) values of
inflation, unemployment, jobs growth, and the PMI into the model from
January 2000 to June 2002. For lagged values of the funds rate, I use
Table 2

Forecasting Changes in the Federal Funds Rate (1988:M1–2002:M6)
ff – ff –3 = α(α0 + α1π–3 + α2u–3 + α3∆e–3 + α4pmi–3 – ff –3 )
Coefficient

Estimate (standard error)

α

.26**
(.07)

α1

1.19**
(.25)

α2

–1.94**
(.28)

α3

.44
(.26)

α4

.21**
(.07)

R2

.546

S.E.

.36

** Significant at the 1 percent level.

VOLUME 1, NUMBER 6, 2002

14

The FOMC began setting an explicit target federal funds rate beginning in June 1989.
Earlier data are based on Manager’s Reports from the Open Market Trading Desk at the
Federal Reserve Bank of New York.

15

The real-time capacity utilization rate is insignificant if it is added to the funds-rate regression. Industrial production growth, retail sales growth, and additional lagged values of the
PMI are also insignificant. In each case, the most recent PMI retains its significance.

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lagged predicted funds rates rather than lagged actual rates. Forecasting
errors are, thus, allowed to cumulate.
Figure 5 shows the results. The model tracks the FOMC’s decisions
fairly well, though it does have some trouble explaining the funds-rate
increases that were implemented during the first half of 2000 and underestimates the rapidity with which the funds rate was cut following
September 11, 2001. This last failing is understandable given the extraordinary nature of September’s events and given that the model’s forecasts
are based on three-month-old data. Despite the potential for forecast
errors to cumulate, the predicted target funds rate eventually stabilizes at
the same level as the actual target rate. It seems fair to conclude that the
Fed’s behavior over the past two and a half years has been largely consistent with and predictable from its behavior during the prior twelve years.
Without the PMI, the predicted funds-rate path starts lower, falls more
slowly, and ends lower than either the actual path or the path predicted with
the PMI’s help. Thus, movements in the PMI are useful for understanding
the FOMC’s decisions during and just prior to the recent recession.
Figure 4

Target Funds Rate (ff ) Moves Toward Its Long-Run Level (ff *)
Percent per year
12
Target funds rate, ff

10

Long-run target rate, ff *

8
6
4
2
0
–2

’88

’89

’90

’91

’92

’93

’94

’95

’96

’97

’98

’99

’00

’01

’02

SOURCES: Federal Reserve Board; author’s calculations.

Figure 5

Predictions Track the Actual Funds Rate Target Fairly Well
Percent per year
7
6
5
4
3

Target funds rate
Predicted, with PMI

2

Predicted, without PMI

1
0
Jan.
2000

Mar.

May

July

Sep.

Nov.

Jan.
2001

Mar.

May

July

Sep.

Nov.

Jan.
2002

Mar.

May

SOURCES: Federal Reserve Board; author’s calculations.

VOLUME 1, NUMBER 6, 2002

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SUMMARY AND CONCLUSIONS
The Purchasing Managers’ Index is a valuable tool for tracking the
health of the economy’s manufacturing sector. It is available on a more
timely basis than other, more direct measures of factory output growth.
Unlike these other measures, it is not subject to significant revisions, and
it seems to capture output growth trends while filtering out a lot of transitory variation. The most recent twenty years of data suggest that factory
output growth tends to be positive or negative depending on whether the
PMI is above or below 47.
The PMI also conveys useful information about real GDP growth. The
threshold for positive GDP growth is a PMI reading of around 40—substantially lower than the reading that serves as a growth threshold for the
manufacturing sector. End-of-quarter changes in the PMI have useful information for aggregate output beyond the information contained in the official reports on employment, retail sales, and industrial production that are
available at or near the close of the quarter. Early estimates of these other
variables miss end-of-quarter fillips to GDP growth that the PMI does not.
Federal Reserve officials draw on information from a wide variety of
sources to gauge the health of the manufacturing sector, which—because
of its interest-rate sensitivity—is an important factor influencing policy
decisions. The PMI is highly correlated with trends in factory output
growth, and policy changes, in turn, are highly correlated with contemporaneous values of the PMI. A forecasting model that draws on the most
recent PMI — along with real-time inflation, unemployment, and jobsgrowth data — does a good job of predicting the general thrust of Federal
Reserve policy over the past fifteen years.
ACKNOWLEDGMENTS
Thanks go to Harvey Rosenblum, Alan Viard, and Mark Wynne for helpful comments and to
Jamie Lee, Dan Lamendola, and Dong Fu for research assistance.

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