How to Read IEA Charts

HOW TO READ I.E.A. CHARTS
"If all else fails, read the instructions."

(For notes on vertical shading and ratio-scale charts,
see Economic Fluctuations in Growth Perspective.)

Note: This page is a web adaptation of a page that was sent out with each subscription to IEA Monthly Charts. To each of the descriptions of features has been added a link to one of the charts that can serve as an example of that feature.

SCALE UNITS

Most IEA charts are presented in the form of ratios or real growth rates (rather than as absolute values. These remove the effects of inflation and, with adjustment of norm lines (see below) for changes in long--run growth trends, they facilitate more meaningful comparison of periods widely separated in time. They also orient the charts horizontally, which facilitates analysis of norms (see below) and trends, and permits more compact presentation.

Where all charts in a panel are measured in the same units (example Figure 2), the units are given (in parentheses) after the title of the panel. Where the charts in a panel have different units (example Figure 1, Panel 4), the units are given (in parentheses) after the title of each individual chart.

Years (Fig 1.A) -- IEA monthly charts cover 15 years. The annual Historical Supplement goes back through 1947. (In the text, references to quarters are abbreviated thus: 75:3 denotes 1975, 3rd quarter.)


A  Years
B  Chart lines
C  Scale Divider
D  Scale Arrow
E  Panel number
F  Series number
G  Reference number
H  Data closing
I  Data guide
J  Stable monthly
KLM  Final values
Figure 1

MAIN CHART LINES   (Fig 1.B)

To facilitate quick visual analysis, most main chart lines are 2-quarter centered (1-2-1 weighted) moving averages for both quarterly and monthly series. (Exceptions: Panels 18-19* and annual-only data.) Since these averages end 4-6 months before the current period, more recent data are shown differently -- see Current Data. (Data are seasonally adjusted unless otherwise noted in the IEA Annotated Chart List.)

SCALES

Scale Divider Line (Fig 1.C) -- separates scale values of adjoining charts.

Scale Unit Marks -- are equidistant and continuous across scale divisions, to facilitate reading values where chart lines overlap. (For current analysis, the norm shading -- see below -- usually makes it unnecessary to refer to actual scale values.)

Overlapping Scales

NORM LINES

"Normal" lines (Fig 2.O) -- most are estimated healthy-economy, balanced growth (full-employment) values. These are similar to the norms for operating ratios, balance-sheet ratios and stock/flow ratios used in scientific business management

Non-horizontal "norm" lines -- indicate trends of continuing structural change.

Some norm lines have a more solid analytical basis than others, many are subject to further revision on the basis of future IEA research, and a few are used merely to facilitate visual analysis -- see Column 4 of the IEA Annotated Chart List. Users can themselves easily test any alternative estimates with black thread or the edge of a transparent ruler.

Norm Shading (Fig 2.P) -- of the deviations from normal facilitates quick visual analysis of the significance of actual developments -- showing where the economy is "out-of-balance," in which direction, and by how much -- like the "normal-indicating" instruments in your car.

Where two charts are presented with a common norm -- e.g. example charts 97.2 and 97.3 -- only one is norm-shaded.

PANEL NUMBER   (Fig 1.E)

Suffix A, B, C, etc. -- indicates a panel subdivision (e.g., 14A, 14B)* or panel continuation.
Prefix R -- a "rotating" panel, which does not appear in every monthly issue.
Prefix A -- whole panel appears only in the annual Historical Supplement.

SERIES SEQUENCE NUMBER   (Fig 1.F)

Within the panel, charts are numbered from top to bottom.
A circle around this number denotes a chart whose basic data are the same as, or comparable to, a National Bureau of Economic Research (NBER) "leading indicator."

REFERENCE NUMBER   (Fig 1.G)

Used to facilitate cross-references from one chart to another and for references in text. Panel numbers appear to the left of the decimal point, series numbers to the right.

Prefix H (in text) -- refers to the annual Historical Supplement version of the chart (rather than the monthly version).

DATA CLOSING DATE   (Fig 1.H)

The data closing date for each issue of IEA Charts varies from month to month so as to permit publication of key data (e.g. GNP, Flow-of-Funds) as soon as possible after their release. All data released by closing date are plotted.

DATA READING GUIDES   (Fig 1.I)

Full-length quarter lines, with monthly subdivisions and mid-quarter months at the top, facilitate identification of recent data. (See also Plotting Positions.)

CURRENT DATA

Relative Stable Monthly Series (Fig 1.J) -- The fine line, with plotting dots, between the main chart line and final value, is a 2-month centered (1-2-1 weighted) moving average.

Final Value -- For all but the most volatile series, final value is unaveraged:

Moderately Volatile Series -- To indicate the degree of caution needed in judging the significance of recent developments, the final fine line is run back 2-3 years:

Most Volatile Series -- wholesale prices (5.1, 5.2, 5.3) and retail sales (15.7) -- use a 5-month centered moving average. (Final plotted value is thus 2 months prior to current month.)


N  Double scales
O  Norm lines
P  Norm shading
QR  Moderately volatile
S  Extreme values
T  War line
U  Continuity break
V  Continuing recession
WX  Official projections
Figure 2

"OFFICIAL" PROJECTIONS   (Fig 2.WX)

These are shown from some series when they are deemed analytically useful and realistic.

Specific value:       Range of values:

EXTREME VALUES   (Fig 2.S)

Where data are "off-the-chart" for more than 2 periods, the numerical values are placed in a "box" with letters designating their periods.

Where data are "off-the-chart" for only 1 or 2 periods, their values are shown vertically at the off-chart periods.

WAR LINE   (Fig 2.T)

Beginning of large-scale U.S. military involvement in Korea and Vietnam. Significant for analysis of structural distortions.

CONTINUITY BREAK   (Fig 2.U)

Change in definition, sample coverage, etc.

CONTINUING RECESSION OR STAGNATION   (Fig 2.V)

Zig-zag edge of recession shading (see Economic Fluctuations in Growth Perspective) indicates that the end of the recession is not yet definitely determined by latest data.

PLOTTING POSITIONS

   
Economic Flows -- income, spending, borrowing during a period (month, quarter, or year) -- are plotted in the middle of the period. (In the upper pair in the example at left, 1st quarter (*) and April (o) are plotted -- see also the charts in example Figure 1.)

Growth Rates -- from one period to the next are plotted between the periods, rather than as "increase since previous period." (In the lower example at left, 1st-2nd quarter (*) and May-June (o) growths are plotted -- see also charts in example Figure 2.)



Written: 1976
Posted: August 4, 2009
To IEA home page
http://www.iea-macro-economics.org