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. sum x2
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
x2 | 8438 55.11448 15.1841 16 111
. gen x21= (x2-55.11448)/15.1841
. sum x21
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
x21 | 8438 1.44e-07 .9999997 -2.576016 3.680529
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. egen x22=std(x2)
. sum x22
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
x22 | 8438 -2.24e-09 1 -2.576017 3.68053
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