Seasonal factors for auto and truck production have been reestimated using final production data through September.  Factors have been revised back through January 1997 and extended through June 2000.  These factors are used in the current IP revision.  The factors will be updated again and extended through December of 2001 when third quarter schedules are released in the spring.
Monthly figures for motor vehicle assemblies in millions of units at annual rate are published at the bottom of Table 2A of the G.17 release.  The formula for seasonally adjusted annual rates (SAAR) of auto and truck production (in millions of units) for each month is

`SAAR = ((NSA data in units/1,000,000) * 12)/(SF * .01).`

The not seasonally adjusted (NSA) data are obtained from Ward's Communications, and
the seasonal factors (SF), which contain adjustments for holiday and length-of-month
effects as well as normal seasonal variation, are shown in the table below.

`Seasonal Factors
          

	                            Trucks
	                     --------------------         
	              Autos      Total      Light
	          ---------  ---------  ---------
	1997 JAN      99.26      99.72      99.88
	1997 FEB     100.08     102.29     102.54
	1997 MAR      97.66     100.20     100.48
	1997 APR     115.97     117.60     117.42
	1997 MAY     110.43     110.89     111.20
	1997 JUN     101.96     101.49     101.42
	1997 JUL      72.41      70.00      68.90
	1997 AUG      98.74      94.09      93.87
	1997 SEP     100.84     103.97     104.17
	1997 OCT     119.52     118.76     118.79
	1997 NOV      93.81      92.28      92.50
	1997 DEC      90.14      89.26      89.22

	1998 JAN      89.92      90.24      90.38
	1998 FEB      99.97     102.75     103.01
	1998 MAR     113.30     116.24     116.59
	1998 APR     105.22     106.80     106.62
	1998 MAY     104.65     105.43     105.70
	1998 JUN     101.49     101.16     101.06
	1998 JUL      73.61      66.94      65.41
	1998 AUG      99.05      93.84      93.64
	1998 SEP     103.40     109.19     109.75
	1998 OCT     114.32     113.41     113.42
	1998 NOV      94.13      92.48      92.70
	1998 DEC      89.92      89.45      89.42

	1999 JAN      89.85      90.26      90.41
	1999 FEB      99.70     103.02     103.29
	1999 MAR     118.50     121.74     122.12
	1999 APR     105.10     106.72     106.53
	1999 MAY     104.43     105.56     105.82
	1999 JUN     111.22     107.67     107.31
	1999 JUL      62.83      60.30      59.06
	1999 AUG     104.96     102.44     102.51
	1999 SEP     104.12     105.50     105.86
	1999 OCT     109.02     108.14     108.15
	1999 NOV      99.71      97.84      98.05
	1999 DEC      89.68      89.61      89.61

	2000 JAN      94.71      95.17      95.35
	2000 FEB     104.32     108.28     108.56
	2000 MAR     118.37     121.85     122.22
	2000 APR      94.53      95.91      95.74
	2000 MAY     109.68     111.18     111.46
	2000 JUN     110.87     110.40     110.20
	2000 JUL      60.81      58.98      57.90
	2000 AUG     109.58     106.54     106.59
	2000 SEP      99.11      96.55      96.68
	2000 OCT     114.19     113.47     113.49
	2000 NOV     100.04      98.18      98.39
	2000 DEC      84.28      84.28      84.29

        2001 JAN      99.64      99.96     100.16
        2001 FEB      98.94     103.08     103.34
        2001 MAR     112.87     116.30     116.64
        2001 APR      99.89     101.23     101.04
        2001 MAY     115.04     116.99     117.30
        2001 JUN     105.65     105.05     104.84`

The table below shows a set of seasonal factors on a weekday average basis;
the adjustment for the number of production days in a month, or weekdays, is shown
separately.  (In the past, we only provided seasonal factors on this basis.)  Using
this information, the  formula for seasonally adjusted annual rates (SAAR) of auto
and truck production (in millions  of units) for each month is

`SAAR = ((NSA data in units/1,000,000) * 260)/(weekdays * SFW * .01).`

Multiplying by 260, the average number of weekdays in a year, converts the weekday
average production to an annual production rate.  This formula reduces to

`SAAR = (NSA data in units * .026) / (weekdays * SFW).



	Seasonal Factors, Weekday Basis (SFW) and Weekdays


	                   Trucks
	            ---------------------        
             Autos       Total       Light    Weekdays
          --------   ---------  ----------  ----------

1997 JAN     93.55      93.92       94.01          23
1997 FEB    108.59     111.39      111.70          20
1997 MAR    101.34     103.41      103.82          21
1997 APR    114.21     115.55      115.43          22
1997 MAY    108.48     108.86      109.17          22
1997 JUN    105.23     103.95      103.91          21
1997 JUL     68.27      65.99       64.96          23
1997 AUG    101.82      97.15       96.91          21
1997 SEP     99.42     102.23      102.33          22
1997 OCT    112.26     111.95      112.01          23
1997 NOV    100.68     100.24      100.42          20
1997 DEC     85.33      84.55       84.46          23

1998 JAN     88.59      88.79       88.86          22
1998 FEB    108.58     112.01      112.35          20
1998 MAR    112.42     114.52      115.01          22
1998 APR    103.61     104.90      104.78          22
1998 MAY    107.56     108.29      108.58          21
1998 JUN    100.01      98.82       98.76          22
1998 JUL     69.42      63.14       61.70          23
1998 AUG    102.15      96.94       96.71          21
1998 SEP    101.96     107.35      107.80          22
1998 OCT    112.19     111.74      111.79          22
1998 NOV     96.01      95.71       95.86          21
1998 DEC     85.21      84.82       84.75          23

1999 JAN     92.74      93.00       93.09          21
1999 FEB    108.32     112.41      112.77          20
1999 MAR    112.65     114.77      115.29          23
1999 APR    103.48     104.75      104.63          22
1999 MAY    107.26     108.33      108.60          21
1999 JUN    109.61     103.00      102.55          22
1999 JUL     61.95      60.03       58.85          22
1999 AUG    103.30     101.99      102.09          22
1999 SEP    102.68     104.67      104.96          22
1999 OCT    112.04     111.68      111.74          21
1999 NOV     96.87      96.70       96.83          22
1999 DEC     85.10      85.02       84.96          23

2000 JAN     97.76      97.98       98.08          21
2000 FEB    108.03     112.58      112.94          21
2000 MAR    111.50     114.78      115.14          23
2000 APR    102.40     103.90      103.72          20
2000 MAY    103.32     104.73      105.00          23
2000 JUN    109.19     108.73      108.53          22
2000 JUL     62.74      60.85       59.74          21
2000 AUG    103.23     100.36      100.41          23
2000 SEP    102.26      99.61       99.75          21
2000 OCT    112.46     111.75      111.77          22
2000 NOV     98.53      96.69       96.90          22
2000 DEC     86.96      86.96       86.97          21

2001 JAN     93.86      94.17       94.35          23
2001 FEB    107.18     111.67      111.95          20
2001 MAR    111.16     114.53      114.87          22
2001 APR    103.06     104.44      104.25          21
2001 MAY    108.37     110.21      110.50          23
2001 JUN    109.01     108.39      108.17          21



December   5,2000
Industrial Output Section
Division of Research and Statistics
Board of Governors of the Federal Reserve System
Washington, D.C. 20551`