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Re: st: calcuating unadjusted and adjusted means
From
Ronan Conroy <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: calcuating unadjusted and adjusted means
Date
Mon, 16 May 2011 10:59:55 +0100
On 2011 Beal 15, at 15:01, Fitzmaurice, Ann E. wrote:
>
> I run the following where the variable bir_grp has four categories was entered in the regression as i.bir_grp2 (sample_mod5 has previously been calculated)
> Regress ............
> predict xb
> rename xb pred_m5
> mean pred_m5 if sample_mod5 ==1 , over (bir_grp2)
>
> adjust if sample_mod5==1, by (bir_grp2)
>
> after this command I get an error message " variable miscbirth not found"
Reproducible. If you run a command after -regress- (in this case, -mean-) you will lose some or all of the stored results needed to run -adjust-.
Incidentally, you can name a predicted variable in the -predict- command, as below.
The solution is to do all the -predict-ing and -adjust-ing first, then run other commands.
. regress mpg weight price
Source | SS df MS Number of obs = 74
-------------+------------------------------ F( 2, 71) = 66.85
Model | 1595.93249 2 797.966246 Prob > F = 0.0000
Residual | 847.526967 71 11.9369995 R-squared = 0.6531
-------------+------------------------------ Adj R-squared = 0.6434
Total | 2443.45946 73 33.4720474 Root MSE = 3.455
------------------------------------------------------------------------------
mpg | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
weight | -.0058175 .0006175 -9.42 0.000 -.0070489 -.0045862
price | -.0000935 .0001627 -0.57 0.567 -.000418 .0002309
_cons | 39.43966 1.621563 24.32 0.000 36.20635 42.67296
------------------------------------------------------------------------------
. predict p_mpg
(option xb assumed; fitted values)
. mean p_mpg, over( foreign)
Mean estimation Number of obs = 74
Domestic: foreign = Domestic
Foreign: foreign = Foreign
--------------------------------------------------------------
Over | Mean Std. Err. [95% Conf. Interval]
-------------+------------------------------------------------
p_mpg |
Domestic | 19.57435 .5887395 18.401 20.74771
Foreign | 25.36971 .5838502 24.2061 26.53332
--------------------------------------------------------------
. adjust, by( foreign)
variable Domestic not found
r(111);
Ronán Conroy
[email protected]
Associate Professor
Division of Population Health Sciences
Royal College of Surgeons in Ireland
Beaux Lane House
Dublin 2
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