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st: -robvar- and number of degrees of freedom
From
Garry Anderson <[email protected]>
To
[email protected]
Subject
st: -robvar- and number of degrees of freedom
Date
Fri, 03 Sep 2010 15:39:20 +1000
Dear Statalist,
The -robvar- command does not seem to be reporting the correct degrees
of freedom.
. webuse auto
(1978 Automobile Data)
. robvar mpg,by(rep78)
Repair | Summary of Mileage (mpg)
Record 1978 | Mean Std. Dev. Freq.
------------+------------------------------------
1 | 21 4.2426407 2
2 | 19.125 3.7583241 8
3 | 19.433333 4.1413252 30
4 | 21.666667 4.9348699 18
5 | 27.363636 8.7323849 11
------------+------------------------------------
Total | 21.289855 5.8664085 69
W0 = 4.7219575 df(5, 68) Pr > F = 0.00092356
W50 = 3.2906157 df(5, 68) Pr > F = 0.01014559
W10 = 4.9744717 df(5, 68) Pr > F = 0.00061062
I would have expected the 5 df to be 4 df because there are 5 groups.
Best wishes, Garry
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