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From |
Richard Williams <Richard.A.Williams.5@nd.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: identify group of observations |

Date |
Wed, 28 Apr 2004 21:47:29 -0500 |

At 06:08 PM 4/28/2004 -0400, MITRA PINAKI (MAR1PXM) wrote:

Does this do what you want? I'm assuming that every time you encounter a 1, you want the groupid increased by 1 and to stay the same until you encounter another 1. In this example there are 3 groups of varying sizes.Hello List, I have a data set where I need to group observations. The identifying flag is two character string which can be either "01" or "02". Each "01" observation is followed by "02", so the flag for the first obs is "01" and the very next one's is "02". But these are always not in pair; order can be "01" and "02"; "01", "02", "02"; "01", "02", "02, "02" and so on. All the "02" obs. followed by "01" belong to one group. Is there any way I can generate an identifier that indicates these groups? Any help will be greatly appreciated.

. list

+----+

| x |

|----|

1. | 01 |

2. | 02 |

3. | 01 |

4. | 02 |

5. | 02 |

|----|

6. | 01 |

7. | 02 |

8. | 02 |

9. | 02 |

10. | 02 |

+----+

. gen groupid = 1 in 1

(9 missing values generated)

. replace groupid = cond(x=="01",groupid[_n-1]+1,groupid[_n-1]) in 2/l

(9 real changes made)

. list

+--------------+

| x groupid |

|--------------|

1. | 01 1 |

2. | 02 1 |

3. | 01 2 |

4. | 02 2 |

5. | 02 2 |

|--------------|

6. | 01 3 |

7. | 02 3 |

8. | 02 3 |

9. | 02 3 |

10. | 02 3 |

+--------------+

-------------------------------------------

Richard Williams, Notre Dame Dept of Sociology

OFFICE: (574)631-6668, (574)631-6463

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EMAIL: Richard.A.Williams.5@ND.Edu

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**References**:**st: identify group of observations***From:*"MITRA PINAKI (MAR1PXM)" <mar1pxm@ups.com>

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