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Re: st: choosing based on number of observations


From   "Sebastian F. B�chte" <[email protected]>
To   [email protected]
Subject   Re: st: choosing based on number of observations
Date   Mon, 16 Apr 2007 17:22:24 +0200

I guess you would like to keep those counties for which at least five
or more observations exist in your dataset. If that is the case this
task can be easily solved with

bysort county: keep if _N>= 5

-bysort- and -by- (which is the same as bysort but it requires a
sorted dataset) are _extremely_ useful commands. You should check out
the corresponding helpfiles and learn more about the versatility of
these commands.

regs
sebastian


On 4/16/07, Alan Neustadtl <[email protected]> wrote:
Do you mean something like:
. keep if county > 5
or
. keep if county > 5 & county <.

Best,
Alan


On 4/16/07, Michael McCulloch <[email protected]> wrote:
> Dear Statalist members,
> I would like to choose records in which the number of observations in
> a field, here named county, is greater than 5. Below is a tabulation
> of county. I've examined the help file for -count-, but this doesn't
> seem to suit my needs. Any guidance would be appreciated. Thank you.
>
> . tab county
>
>    COUNTY OF |
> RESIDENCE @ |
>           DX |      Freq.     Percent        Cum.
> ------------+-----------------------------------
>            0 |         34        0.61        0.61
>            1 |      1,055       18.78       19.39
>            3 |         23        0.41       19.80
>            4 |         11        0.20       19.99
>            5 |          8        0.14       20.14
>            6 |          3        0.05       20.19
>            7 |        656       11.68       31.87
>            9 |         53        0.94       32.81
>           10 |          6        0.11       32.92
>           12 |          4        0.07       32.99
>           15 |          1        0.02       33.01
>           17 |         38        0.68       33.68
>           18 |          1        0.02       33.70
>           19 |          2        0.04       33.74
>           20 |          2        0.04       33.77
>           21 |        174        3.10       36.87
>           22 |          1        0.02       36.89
>           23 |         10        0.18       37.07
>           27 |          6        0.11       37.17
>           28 |        104        1.85       39.02
>           29 |         27        0.48       39.51
>           31 |        102        1.82       41.32
>           32 |          1        0.02       41.34
>           33 |          2        0.04       41.37
>           34 |        855       15.22       56.60
>           35 |          6        0.11       56.70
>           36 |          1        0.02       56.72
>           37 |          2        0.04       56.76
>           38 |        445        7.92       64.68
>           39 |         85        1.51       66.19
>           40 |          2        0.04       66.23
>           41 |        430        7.66       73.88
>           43 |        699       12.44       86.33
>           44 |         27        0.48       86.81
>           45 |          5        0.09       86.90
>           48 |        362        6.44       93.34
>           49 |        255        4.54       97.88
>           50 |         22        0.39       98.27
>           51 |          7        0.12       98.40
>           52 |          2        0.04       98.43
>           53 |          1        0.02       98.45
>           54 |          3        0.05       98.50
>           55 |         13        0.23       98.74
>           57 |         54        0.96       99.70
>           58 |         12        0.21       99.91
>          230 |          1        0.02       99.93
>          641 |          1        0.02       99.95
>          999 |          3        0.05      100.00
> ------------+-----------------------------------
>        Total |      5,617      100.00
> *
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