Purchasing Managers' Indexes (PMI) are economic indicators derived from monthly
surveys of private sector companies. The two principal producers of PMIs are Institute for Supply Management (ISM), which originated the
manufacturing and non-manufacturing metrics and which produces them for the
United States and Markit Group, which produces metrics based on ISM's work for over 30 countries
worldwide.
ISM and Markit Group separately compile Purchasing Managers' Index (PMI)
surveys on a monthly basis by polling businesses which represent the makeup of
the respective business sector. ISM's surveys cover all NAICS categories. The Markit survey covers
private sector companies, but not the public sector.
The current ISM PMI survey can be found under "ISM Reports On
Business" on the ISM home page, or directly on this page. The surveys are
released shortly after the end of the reference period. The actual release
dates depend on the sector covered by the survey. Manufacturing data are
generally released on the first business day of the month, followed by
construction (Markit only) on the second working day, and
non-manufacturing/services on the third business day.
ISM began to produce the report for the USA in 1948. The data for the index
are collected through a survey of 400 purchasing managers in the manufacturing
sector on seven different fields, namely, production level, new orders from
customers, speed of supplier deliveries, inventories, order backlogs and
employment level. Respondents can report either better, same or worse
conditions than previous months. For all these fields the percentage of
respondents that reported better conditions than the previous months is calculated.
The five percentages are multiplied by a weighing factor (the factors adding to
1) and are added.
The Chicago-PMI survey, owned by Deutsche Börse, registers manufacturing
and non-manufacturing activity in the Chicago Region. Investors value this indicator because the Chicago
region somewhat mirrors the United States overall in its distribution of
manufacturing and non-manufacturing activity.
The predominant operator and owner of Purchasing Managers Index series
outside the USA is the Markit Group. Markit issue
most of their PMIs in partnership with other companies.
The Markit and ISM Purchasing Managers Indices include additional sub
indices for manufacturing surveys such as new orders, employment, exports,
stocks of raw materials and finished goods, prices of inputs and finished
goods.
Formula, calculation, and reading:where:
- P1
= Percentage number of answers that reported an improvement.
- P2
= Percentage number of answers that reported no change.
- P3
= Percentage number of answers that reported a deterioration.
Thus, if 100% of the panel reported an improvement, the index would be
100.0. If 100% reported a deterioration, the index would be zero. If 100% of
the panel saw no change, the index would be 50.0 (P2 * 0.5).
Therefore, an index reading of 50.0 means that the variable is unchanged, a
number over 50.0 indicates an improvement, while anything below 50.0 suggests a
decline. An index of 50.0 would arise if either all respondents reported no
change or the number of respondents reporting an improvement was matched by the
number of respondents reporting a deterioration. The further away from 50.0 the
index is, the stronger the change over the month, e.g. a reading of 55.0 points
to a more frequently reported increase in a variable than a reading of 52.5.
The degree of confidence experienced by respondents reporting an improvement
and the degree of concern experienced by respondents reporting a deterioration
are not factored into the index.
Headline Manufacturing PMI:
The headline manufacturing PMI is a composite of five of the survey
indices. These are New orders, Output, Employment, Suppliers' delivery times
(inverted) and Stocks of purchases. The ISM attributes each of these variables
the same weighting when calculating the overall PMI, whereas Markit uses the
following weights: New orders (0.3), Output (0.25), Employment (0.2),
Suppliers' Delivery Times (0.15), Stocks of purchases (0.1).
Markit Economics' PMI surveys:
Survey Panels
Purchasing managers form a near ideal survey sample base, having access to
information often denied to many other managers. Due to the nature of their job
function, it is important that purchasing managers are among the first to know
when trading conditions, and therefore company performance, change for the
better or worse. Markit therefore uses such executives to produce data on
business conditions.
In each country, a panel of purchasing managers is carefully selected by
Markit, designed to accurately represent the true structure of the chosen
sector of the economy as determined by official data. Generally, value added
data are used at two-digit SIC level, with a further breakdown by company size
analysis where possible. The survey panels therefore replicate the actual
economy in miniature. A weighting system is also incorporated into the survey
database that weights each response by company size and the relative importance
of the sector in which that company operates.
Particular effort is made to achieve monthly survey response rates of around
80%, ensuring that an accurate picture of business conditions is recorded over
time.
Data are collected in the second half of each month via mail, email, web,
fax and phone.
Questionnaires:
A key feature of the PMI surveys is that they ask only for factual
information. They are not surveys of opinions, intentions or expectations and
the data therefore represent the closest one can get to “hard data” without
asking for actual figures from companies.
Questions asked relate to key variables such as output, new orders, prices
and employment. Questions take the form of up/down/same replies. For example,
“Is your company’s output higher, the same or lower than one month ago?”
Respondents are asked to take expected seasonal influences into account
when considering their replies.
For each main survey question, respondents are asked to provide a reason
for any change on the previous month, if known. This assists not only the
understanding of variable movement but also in the seasonal process when X12
cannot be used.
Seasonal adjustment:
The seasonal adjustment of PMI survey data is usually calculated using the X12 statistical programme of adjustment,
as used by governmental statistical bodies in many developed countries.
However, the X12 programme only produces satisfactory data if five years'
historical data are available. In the absence of such a history of data, the
PMI survey data are seasonally adjusted using an alternative method (see next
paragraph), developed by Markit Economics.
This method was initially designed to provide analysts with a guide to the
underlying trend in the survey data and should be recognised as a second-best
approach to X12. However, past experience in other countries suggests that
Markit’s method of seasonal adjustment goes beyond this initial purpose and in
fact in many cases outperforms X12 as a guide to comparable official data.
Markit's method involves using reasons cited by responding survey panel
member companies for changes in variables, which are then used to ascertain
whether a reported increase or decrease in each variable reflects an underlying
change in economic conditions or simply a seasonal variation. Seasonal
variations may include changes in demand arising from Christmas, Easter or
other public holidays. Normal, expected changes in weather are not included.
The net balance of companies reporting an improvement in a variable less those
reporting a deterioration is then adjusted to allow for the percentages of
companies reporting seasonal induced increases or decreases in the variable.
Other PMI Surveys:
Similar purchasing managers indices are published by the Ifo Institute for Economic Research in Germany, the
Bank of Japan in Japan (Tankan), the Caixin China PMI published by Markit and the Swedish PMI run by private
bank Swedbank.
The PRIX index uses a diffusion index methodology based on that of PMIs. However, rather
than drawing on purchasing managers, it uses country analysts based in the
world's 20 largest oil exporting countries to forecast political events that
may affect global oil exports. The PRIX index is updated quarterly and
published for free on the internet.
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