You may have to average each visit including screening, then do the change of mean for each visit from the mean of screening. Of course, you have to ask your statistician, who might have already discussed this in the SAP.

On Wed, 21 Jan 2009 08:12:06 -0800, Al <ali6058@GMAIL.COM> wrote:

>Hi All, > I have a dataset in the following structure.. I am looking >to create a dataset change from Screening to visit.. >Strange thing is that the test was performed three times at scr and >three times at each visit .. so i am having trouble >creating the change from screening to each visit values .. i cannot >envision how the final dataset will look like.. >any suggestions... > > PAT VIS TES SEQ RES > 111 Scr SYSBP 1 106 > 111 Scr SYSBP 3 106 > 111 Scr SYSBP 5 114 > 111 Vis1 SYSBP 12 116 > 111 Vis1 SYSBP 14 118 > 111 Vis1 SYSBP 16 112 > 111 Vis2 SYSBP 21 110 > 111 Vis2 SYSBP 23 103 > 111 Vis2 SYSBP 25 111 > > 222 Scr SYSBP 1 102 > 222 Scr SYSBP 3 106 > 222 Scr SYSBP 5 98 > 222 Vis1 SYSBP 12 120 > 222 Vis1 SYSBP 14 112 > 222 Vis1 SYSBP 16 114 > 222 Vis2 SYSBP 21 105 > 222 Vis2 SYSBP 23 111 > 222 Vis2 SYSBP 25 107 > > > Thanks in advance > Al