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Re: st: Force x-axis range to be the bounds of the variable in the sample, not the entire data set
From
Nick Cox <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: Force x-axis range to be the bounds of the variable in the sample, not the entire data set
Date
Mon, 27 Aug 2012 18:24:41 +0100
The x axis range you get is unrestricted because your -rarea- call is
unrestricted. Try adding an -if- qualifier to that too.
Nick
On 27 Aug 2012, at 17:05, Aaron Kirkman <[email protected]> wrote:
I'm calculating and generating prediction intervals for a subset of a
data set, but when I graph the subset, the range on the x-axis is the
range of all of the data, instead of only the sample. For example:
###
use "http://www.stata-press.com/data/imeus/hprice2a", clear
sort lnox
summ lnox
summ lnox if _n <= 100
###
. summ lnox
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
lnox | 506 1.693091 .2014102 1.348073 2.164472
. summ lnox if _n <= 100
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
lnox | 100 1.435845 .0361544 1.348073 1.48614
The range of the sample is [1.348073, .48614], but when I calculate
and graph the predicted values, the range of -lnox- is [1.348073,
2.164472], which is too large. Here is the complete do-file:
###
use "http://www.stata-press.com/data/imeus/hprice2a", clear
sort lnox
summ lnox
summ lnox if _n <= 100
quietly regress lprice lnox if _n <= 100
predict double xb if e(sample)
predict double stdpred if e(sample), stdp
scalar tval = invttail(e(df_r), 0.975)
gen double uplim = xb + tval * stdpred
gen double lowlim = xb - tval * stdpred
summ lnox if e(sample), meanonly
local lnoxbar = r(mean)
label var xb "Predicted"
label var uplim "95% prediction interval"
label var lowlim "95% prediction interval"
#delimit ;
twoway
(rarea lowlim uplim lnox, sort bcolor(gs14))
(scatter lprice lnox if e(sample), sort ms(Oh) xline(`lnoxbar'))
(rline uplim lowlim lnox if e(sample), sort),
ytitle("Actual and predicted log price") legend(cols(1))
xsize(18) ysize(12);
#delimit cr
###
Is there a way to automatically do this, or should I manually specify
-xaxis- and -xlabel- ?
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