Hello,

I didn't give enough information when I sent an query before, so I'm trying
again with a more detailed explanation:

In this data set, each patient has a different number of measured variables
(they represent tumors, so some people had 2 tumors, some had 5, etc). The
problem I have is that often in later cycles for a patient, tumors that
were originally measured are now missing (or a "new" tumor showed up). We
assume there are many different reasons for why a tumor would be measured
in one cycle and not another, and so I want to subset OUT the "problem"
patients to better study these patterns.

An example:

Patient  Cycle  V1  V2  V3  V4  V5
A  1  0.4  0.1  0.5  1.5  NA
A  2  0.3  0.2  0.5  1.6  NA
A  3  0.3  NA  0.6  1.7  NA
A  4  0.4  NA  0.4  1.8  NA
A  5  0.5  0.2  0.5  1.5  NA

I want to keep patient A; they have 4 measured tumors, but tumor 2 is
missing data for cycles 3 and 4

B  1  0.4  NA  NA  NA  NA
B  2  0.4  NA  NA  NA  NA

I do not want to keep patient B; they have 1 tumor that is measure
consistently in both cycles

C  1  0.9  0.9  0.9  NA  NA
C  3  0.3  0.5  0.6  NA  NA
C  4  NA  NA  NA  NA  NA
C  5  0.4  NA  NA  NA  NA

I do want to keep patient C; all their data is missing for cycle 4 and
cycle 5 only measured one tumor

D  1  0.2  0.5  NA  NA  NA
D  2  0.5  0.7  NA  NA  NA
D  4  0.6  0.4  NA  NA  NA
D  5  0.5  0.5  NA  NA  NA

I do not want patient D, their two tumors were measured each cycle

E  1  0.1  NA  NA  NA  NA
E  2  0.5  0.3  NA  NA  NA
E  3  0.4  0.3  NA  NA  NA

I DO want patient E; they only had one tumor register in Cycle 1, but
cycles 2 and 3 had two tumors.


Thanks for any help!

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