                                                      9 February 1988

Example 4:   Three series that are unsuitable for seasonal adjustment
             (m1gold.spc, m2airc.spc, and x1gold.spc), as various 
             diagnostics in the output show.  Look at the M and Q
             statistics and the sliding span diagnostics.

             Suggested graphs:  overlay graph of the original and
             seasonally adjusted series, seasonal factors by month,
             and year on year graphs.

             Two of the spec files are listed below. 



# Example 4:  m1gold.spc  

# This series, US Imports of Gold, has no stable seasonality.  X-12-ARIMA
# rejects adjustment of such a series.  

 series      {period=12
              title=' '                                         
              file='m1gold.ori'                                 
              name='m1gold'                                     
              start=1979.01                                       
              print=(brief)                                     
              span=(1980.01,)                                       
             }                                                  
 transform   {function=log}                                                  
 arima       {model=(0 1 1)}                                                  
 check       { }                                                  
 estimate    {print=(brief)}                                                  
 outlier     {types=all}                                                  
 x11         {mode=mult
              seasonalma=(s3x5)                                 
              print=(brief +d8 +d9 +d13)                        
             }                                                  
 slidingspans{outlier=keep                                      
              fixmdl=yes                                        
             }                                                  
 forecast    {maxlead=24                                         
             }                                                  



# Example 4:  x1gold.spc  

# This series, US Exports of Gold, has no stable seasonality.  X-12-ARIMA
# rejects adjustment of such a series.  

 series      {period=12                                         
              title='X-12-ARIMA run for x1gold'                                         
              file='x1gold.ori'                                 
              name='x1gold'                                     
              start=1979.01                                       
              print=(brief)                                     
              span=(1982.01,)                                       
             }                                                  
 transform   {function=log}    
 regression  {variables=(td1coef ao1986.3 ao1986.5 ao1986.6 ao1986.7)
             }                                              
 arima       {model=(0 1 1)(0 1 1)}                                                  
 check       {print=all}
 outlier     {print=brief}                                        
 x11         {mode=mult                                       
              seasonalma=(s3x9)                                 
              print=(brief +d8 +d9 +d13)                        
             }                                                  
 slidingspans{outlier=keep                                      
              fixmdl=yes                                        
             }                                                  
 forecast    {maxlead=24                                         
             }
