Board of Governors of the Federal Reserve System

Documentation for the Revision History of Industrial Production

I. Introduction:

This file provides data showing the seasonally adjusted indexes for total industrial production, manufacturing, mining, and utilities, as they were originally published and subsequently revised during the normal six-month estimation period. For each industry group, the file includes a time series showing the level of the index as it was initially published as well as six time series showing its level when published one, two, three, four, five, and six months after its initial release. The estimate published six months after the initial release is usually the same as that published five months after the initial release, except when an annual or major revision was issued. Each time series, by itself, has discrete breaks at the time of annual revisions. Some come when IP has been estimated using a new base year.

In addition to the revision history for the index levels, the revision history for the reliability estimates found in table 15 of the G.17 release are included in this file.

II. Data format and file information:

The data file name is revh_sa.txt.

Data format:

Data begin in January 1972 for all of the index levels except the fifth and sixth revisions, which begin in 2007. The ending date for the initial estimate is the year and month of the most recent Industrial Production Index (designated in the data file naming convention, YYMM). Data are written in ASCII format with four decimal places, twelve months of data per line for complete years.

The series codes are composed of three fields, a prefix, an industry code, and a suffix, separated by a period. For this revision history, only total IP, manufacturing, mining, and utilities, are included. Only estimates for the seasonally adjusted data are included.

The prefixes used in the variable names (i.e., init., rev1., rev2., rev3., rev4., rev5., and rev6.) denote the timing of the publication of the data.

	init.	Initial index level, published about 15 days after 
		the end of the month.

	rev1.   first revision, published about 45 days after 
		the end of the month.

	rev2.	second revision, published about 75 days after 
		the end of the month.

	rev3.   third revision, published about 105 days after 
		the end of the month.

	rev4.	fourth revision, published about 135 days after 
		the end of the month.

	rev5.	fifth revision, published about 165 days after 
		the end of the month. 


	rev6.	sixth revision, published about 195 days after 
		the end of the month.   (Usually identical to fifth 
                revision, except when there was an annual or major
                revision.)

The industry codes are:

        B50001:  Total industrial production
        B00004:  Manufacturing
        G21:     Mining
        G2211A2: Electric and gas utilities

The third fragment of the name is one of the following:

        S:      Index level
        S85:    85th percentile for index level        
        S15:    15th percentile for index level        
        PCT:    Monthly percentage change 
        PCT85:  85th percentile for monthly percentage change        
        PCT15:  15th percentile for monthly percentage change         
        QPCT:   Quarterly percentage change 
        QPCT85: 85th percentile for quarterly percentage change        
        QPCT15: 15th percentile for quarterly percentage change         

For example, the initial February 2008 value was published in the middle of March 2008. At the same time, the first revision of the January 2008 value was being published.

III. Calculation of growth rates:

Computing growth rates similar to those actually published requires some care. For example, one should divide the initial estimate of February 2008 (published in mid-March 2008) by the first revision of January 2008 IP (also published in mid-March 2008) to get the initial estimate of growth in February 2008. Use the following formulas to calculate the published growth rates for a series:

 Initial growth rate:			100 * ((init[t] / rev1[t-1]) - 1)
						    	      
 First revision of growth rate:		100 * ((rev1[t] / rev2[t-1]) - 1)
						    	      
 Second revision of growth rate:	100 * ((rev2[t] / rev3[t-1]) - 1)
						    	      
 Third revision of growth rate:		100 * ((rev3[t] / rev4[t-1]) - 1)

 Fourth revision of growth rate:	100 * ((rev4[t] / rev5[t-1]) - 1)

 Fifth revision of growth rate:		100 * ((rev5[t] / rev6[t-1]) - 1)

Estimates of the index levels prior to 1992 are only available to 1 decimal place so percent changes calculated from them may sometimes round differently than the growth rates actually published, which are based on unrounded data. The four decimal accuracy provided in the file after 1992 will usually yield a growth rate that rounds to the one published.