Dan,

I, too, am already brain dead for the night, but is the following what you were trying to accomplish?:

data want; set have; array x[7] A--G; do _n_ = 1 to &n_miss; ndx = ceil(7*uniform(123)); do while(x[ndx] EQ .); ndx = ceil(7*uniform(123)); end; x[ndx] = .; end; x_mean = mean(of x(*)); do _n_ = 1 to 7; if missing(x[_n_]) then x[_n_] = x_mean; end; run;

Art --------- On Thu, 11 Nov 2010 18:40:38 -0800, Nordlund, Dan (DSHS/RDA) <NordlDJ@DSHS.WA.GOV> wrote:

>> -----Original Message----- >> From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of >> Nordlund, Dan (DSHS/RDA) >> Sent: Thursday, November 11, 2010 5:22 PM >> To: SAS-L@LISTSERV.UGA.EDU >> Subject: Re: creating missing randomly >> >> > -----Original Message----- >> > From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of >> > yk2k >> > Sent: Thursday, November 11, 2010 4:13 PM >> > To: SAS-L@LISTSERV.UGA.EDU >> > Subject: creating missing randomly >> > >> > Hi, I'm trying to creat new datasets that contains missing vlaues >> using >> > exist data. >> > >> > If I have a data that contains 7 continuous variables like below. >> > >> > A B C D E F G >> > 1 3 4 3 2 3 4 >> > 2 4 3 4 5 6 2 >> > 2 5 3 4 5 3 1 >> > 1 2 3 3 2 1 3 >> > 2 5 4 3 4 1 3 >> > >> > I want to make missing randomly, but same number of missing within >> each >> > person like below. >> > >> > data-1 (1 missing per person) >> > >> > A B C D E F G >> > 1 . 4 3 2 3 4 >> > 2 4 3 . 5 6 2 >> > 2 5 . 4 5 3 1 >> > . 2 3 3 2 1 3 >> > 2 5 4 3 4 . 3 >> > >> > data-2 (2 missing per person) >> > >> > A B C D E F G >> > 1 . 4 3 . 3 4 >> > 2 4 . . 5 6 2 >> > 2 5 . 4 5 . 1 >> > . 2 3 3 . 1 3 >> > 2 5 . 3 4 . 3 >> > >> > ...up to 6 missings per person. >> > >> > Also, is there any way to replace the missing value with mean of rest >> > of >> > values? >> > >> > Thanks. >> >> Here is one way to do it: >> >> data have; >> input A B C D E F G; >> cards; >> 1 3 4 3 2 3 4 >> 2 4 3 4 5 6 2 >> 2 5 3 4 5 3 1 >> 1 2 3 3 2 1 3 >> 2 5 4 3 4 1 3 >> ; >> run; >> >> **----replace n_miss values with missing----**; >> %let n_miss = 2; >> data want1; >> set have; >> array x[7] A--G; >> do _n_ = 1 to &n_miss; >> ndx = ceil(7*uniform(123)); >> do while(x[ndx] EQ .); >> ndx = ceil(7*uniform(123)); >> end; >> x[ndx] = .; >> end; >> run; >> proc print; >> run; >> >> **----replace n_miss values with mean of remaining values----**; >> data want2; >> set have; >> array x[7] A--G; >> do _n_ = 1 to &n_miss; >> ndx = ceil(7*uniform(123)); >> do while(x[ndx] EQ .); >> ndx = ceil(7*uniform(123)); >> end; >> x[ndx] = .; >> end; >> x_mean = mean(of A--G); >> do _n_ = 1 to 7; >> if missing(x[_n_]) then x[_n_] = x_mean; >> end; >> run; >> proc print; >> run; >> >> Hope this is helpful, >> >> Dan > >OK, this wasn't as helpful as I had planned. WANT1 was created as I expected, with missing randomly inserted. However, WANT2 is not correct. The wrong values are changed and the mean isn't always inserted (although the initial missings are inserted randomly). If I create WANT3, where instead of replacing by the mean, I replace with a constant (99 for example), then the data step works as I expect. I am obviously brain dead at this point. Can someone point out the error of my ways? Thanks. > >data have; > input A B C D E F G; >cards; >1 3 4 3 2 3 4 >2 4 3 4 5 6 2 >2 5 3 4 5 3 1 >1 2 3 3 2 1 3 >2 5 4 3 4 1 3 >; >run; > >**----replace n_miss values with missing----**; >%let n_miss = 2; >data want1; > set have; > array x[7] A--G; > do _n_ = 1 to &n_miss; > ndx = ceil(7*uniform(123)); > do while(x[ndx] EQ .); > ndx = ceil(7*uniform(123)); > end; > x[ndx] = .; > end; >run; >proc print; >run; > >**----replace n_miss values with mean of remaining values----**; >data want2; > set have; > array x[7] A--G; > do _n_ = 1 to &n_miss; > ndx = ceil(7*uniform(123)); > do while(x[ndx] EQ .); > ndx = ceil(7*uniform(123)); > end; > x[ndx] = .; > end; > x_mean = mean(of A--G); > do _n_ = 1 to 7; > if missing(x[_n_]) then x[_n_] = x_mean; > end; >run; >proc print; >run; > >**----replace n_miss values with a constant (99)----**; >data want2; > set have; > array x[7] A--G; > do _n_ = 1 to &n_miss; > ndx = ceil(7*uniform(123)); > do while(x[ndx] EQ .); > ndx = ceil(7*uniform(123)); > end; > x[ndx] = .; > end; > x_mean = mean(of A--G); > do _n_ = 1 to 7; > if missing(x[_n_]) then x[_n_] = 99; > end; >run; >proc print; >run; > > >Dan > >Daniel J. Nordlund >Washington State Department of Social and Health Services >Planning, Performance, and Accountability >Research and Data Analysis Division >Olympia, WA 98504-5204