 Usage:  {zlag}=panlag(z,a, {T})  
 
 Input:

  z Dataset              NT x {2+} + k Matrix 
                         
  T Number of time periods for a BALANCED Dataset  scalar 
                         a Konstante fr y(i,t)=(1-a)*z(i,t)+a*z(i,t-1) 
                         scalar 
                         
 Output:

  zlag Output matrix with (Ti-1)*N Observations  string 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
