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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: A Problem on generating a variable using --appended-dataset |

Date |
Mon, 19 Nov 2007 10:17:26 -0000 |

You can't -generate- a variable that already exists. That is basic: read about -generate- and -replace-. You may want to -generate- outside the loop and -replace ... in `i'- within the loop. gen X = . forval i = 44/93 { replace ... in `i' } Asgar Khademvatani Basically, I am estimating a cost model using time series dataset over 1958-2000. Then, I have appended a new observation over 2001-2050 to my master dataset in the Stata memory, using--append-- command. I want to generate some new variables defined based on functions upon estimated coefficient and the other variables, I want generate these variables only over 2001-2050 during the same period of new using observation.Actually, I already tried --gen-- command but it only generate the variables over master dataset period over 1958-2000 NOT over 2001-2050. In doing so, I am going to write a --forvalues-- loop to do so. But the variables only are generated at one single observation,say only 2001, and it is re-extended over other years with the same values . For example, my written loop and the stata results are given as: A Sample Loop: forvalues i = 44/93 { gen X = _b[le_sg] + _b[lple_sg]*(plpl_sg[`i']) + _b[lpme_sg]*(plpm_sg[`i']) + _b[lek_neg_sg]*(plk_sg[`i']) + _b[let_sg]*(pt[`i']) list X } The Stata Output: do "C:\DOCUME~1\ASGARK~1\LOCALS~1\Temp\STD0i000000.tmp" . 1. forvalues i = 44/93 { 2. gen X =_b[le_sg] + _b[lple_sg]*(plpl_sg[`i']) + _b[lpme_sg]*(plpm_sg[`i']) + _b[lek_neg_sg]*(plk > _sg[`i']) + _b[let_sg]*(pt[`i']) 3. list X 4. } 44 +-----------+ | X |-----------| 1. | -7.730469 | 94. | -7.730469 | +-----------+ X already defined r(110); end of do-file As you see in the above, X variable is generated only in 2001 and it is repeated over next years with the same value. I am not sure what is wrong with my loop. May somebody please help me out on this matter and tell me what is wrong with that? Otherwise, I am just wondering that is there another way other than writing a loop for generating the variables over 2001-2050? * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: A Problem on generating a variable using --appended-dataset***From:*Asgar Khademvatani <akhademv@ucalgary.ca>

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