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

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

Subject |
RE: st: RE: RE: Use foreach or forvalues to create the long form data |

Date |
Thu, 16 Oct 2008 16:50:09 +0100 |

Your problem is much clearer, but I don't have much comfort for you. Your best chance of getting things done much faster is with a different hardware set-up. Naturally I have no idea what is possible for you. If this were my problem, I would be thinking about two quite different strategies: 1. Letting -reshape- chug along and doing something else while I wait. Sometimes one can waste more time finding a better way than you save. 2. Taking a sample of 10000 and seeing if I could get a model even to converge (see Austin's post). Nick n.j.cox@durham.ac.uk Supnithadnaporn, Anupit Martin and Nick, thank you so much. Your suggestion works very well. I am sorry for being unclear about my question. I will clarify it now. I have a large dataset around 1 million records. There are around 20 variables. I would like to run the clogit regression, which requires me to reshape the data into the long form. Basically, it is the model of a person choosing a product from the choice set of 12. Thus, the total records would be of 12 million after reshaping. In the beginning, I tried with the smaller sample and reshape worked very slow. Then, I thought I should start with only 2 ID variables: person ID and choice ID (1-12). I created the wide form data of only 2 ID variables, reshaped it to the long form, and lastly merged other variables that are associate with person and choice respectively. However, even with the only 2 ID variables, it took a long time for reshape to finish for the small sample of the total 1 million records. That is why I try to find the faster way to create the empty dataset with 2 ID variables first. Then my next step is to merge the information about a person and the choice. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: RE: RE: Use foreach or forvalues to create the long form data***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: RE: RE: Use foreach or forvalues to create the long form data***From:*"Supnithadnaporn, Anupit" <gtg065t@mail.gatech.edu>

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