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From |
David Kantor <[email protected]> |

To |
[email protected] |

Subject |
Re: st: more bizarre missing observations |

Date |
Thu, 09 Oct 2003 09:08:57 -0400 |

At 12:43 PM 10/9/2003 +0100, Kristien Verheyen wrote:

By default, -tabulate- omits missing observations, so the behavior you see is completely expected.I have a similar problem to Robert's in that I know for sure there are missing data for a particular variable ('canter') but if I type tab canter if canter==. I am told there are 'no observations' canter is stored as float but following Neil's suggestion still gives me 'no observations'. Please can anyone tell me how I find out exactly how many missing values there are? Thank you, Kristien Verheyen [...]

If you want to see the missings, then code...

tab canter if canter==. , mis

which will allow the missings to be shown.

But note that such a tabulation will have only one row: missing (.). You can get the same information by...

count if canter==.

Another issue to consider is, do you use Stata 8 or an earlier edition? If you have Stata 8, then to test canter==. is to seek a specific missing value: . But there are others: .a, .b, .c, etc.. If you want to get all missing values, then you should test...

missing(canter)

or, equivalently,

mi(canter)

or, equivalently,

canter <.

Thus, a tabulation such as

tab canter if mi(canter), mis

will show you all the different species of missing values. And

count if mi(canter)

will just give you the total, regardless of the species.

I hope this helps.

-- David

(The missing() function exists at least as far back as Stata 6. The mi() function, as a synonym for missing() came later -- I'm not sure if it is Stata 7 or 8.)

David Kantor

Institute for Policy Studies

Johns Hopkins University

[email protected]

410-516-5404

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**Follow-Ups**:**RE: st: more bizarre missing observations***From:*"Nick Cox" <[email protected]>

**References**:**st: more bizarre missing observations***From:*KRISTIEN VERHEYEN <[email protected]>

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