Can you suggest the right command?

[Martin Imelda Borg]

Hi I have a group of individuals stored under (ID no) where 1 is the same individual, 2 is a separte individual and so on.
vistno - is the number of times the individual when to clinic
MI - is the condition the patient had

Question:
For each groups of indviduals, I want to generate a new variable 'ch1' whereby if in the MI column there is any presence of a '1' (as MI is binary)
I would like to be coded as 1 only once

SO

If the same patient eg Individual2 went to a clinic twice, and had MI as 1 on each occasion, I only want it to appear once in the column ch1

As you can see I tried:
by IDno: egen ch1 = max(MI)

However, this would code 1 for each time the individual (Idno) went to the clinic, when I only want Stata to just detect if ever the individual had a '1' on any occasion that person went to clinic.

I can't not use the duplicate command - as you can see the numbers within the variables vary.

* Example generated by -dataex-. For more info, type help dataex
clear
input float(IDno visitno MI ch1)
1 1 0 0
1 2 0 0
2 1 1 1
2 2 1 1
3 1 1 1
3 2 1 1
3 3 1 1
4 1 0 1
4 2 0 1
4 3 1 1
4 4 1 1
end

[Martin Imelda Borg]

I have also tried this:

egen test = max(MI), by(IDno)

* Example generated by -dataex-. For more info, type help dataex
clear
input float(IDno visitno MI test)
1 1 0 0
1 2 0 0
2 2 1 1
2 3 1 1
2 1 1 1
3 3 1 1
3 5 1 1
3 4 1 1
3 2 1 1
3 1 1 1
4 5 0 0
4 4 1 1
4 1 0 1
4 3 1 1
4 2 0 1
end

As you can see I would like to see the red text only and the remaining being 0.
But with the above code its generate the Max no (which would be 1) for anytime it appears in MI and hence subsequently repeats itself per IDno in the test variable

[Martin Imelda Borg]

Hi there (again) - So I actually found the command
This seems to work

collapse (max) MI, by(IDno)

As it produces this:

* Example generated by -dataex-. For more info, type help dataex
clear
input float(IDno MI)
1 0
2 1
3 1
4 1
end

However, as I need to do this for 10 other variables and it seems cumbersome to keep saving the data all the time.....
Is there a shorter way to this ?

[Hemanshu Kumar]

You can do this for multiple variables in a single -collapse- command. See

help collapse