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Re: st: Identifying Experiment subjects that belong in both the Placebo and Experiment Groups
From
Beatrice Benavidez <[email protected]>
To
[email protected]
Subject
Re: st: Identifying Experiment subjects that belong in both the Placebo and Experiment Groups
Date
Mon, 22 Oct 2012 14:30:20 +0400
Thank you for your reply. But what if my dataset is structured like below:
Date ID Received
18/1 3 Treatment
19/1 3 Placebo
20/1 3 Treatment
18/1 4 Placebo
18/1 4 Treatment
18/1 4 Placebo
18/1 4 Treatment
The particular ID's first and last observation may be the same but the
in-betweens are different.
The line "bysort ID (Received) : gen bad = Received[1] !=
Received[_N]" may not work as [1] and [_N] only deals with first and
last respectively.
How would I run this where the number of date/treatment occurrences
differs from one ID to another? How do I take into account if the
Received observation is different from one occurrence to the next and
not just from the first and last occurrence.
Thank you.
Kind regards,
Beatrice
------------------------------
Date: Sun, 21 Oct 2012 12:44:33 +0100
From: Nick Cox <[email protected]>
Subject: Re: st: Identifying Experiment subjects that belong in both
the Placebo and Experiment Groups
This is an FAQ. See
How do I list observations in a group that differ on a variable?
http://www.stata.com/support/faqs/data-management/listing-observations-in-group/
bysort ID (Received) : gen bad = Received[1] != Received[_N]
Nick
On Sun, Oct 21, 2012 at 12:38 PM, Beatrice Benavidez
<[email protected]> wrote:
> I have a dataset like below but for thousands of subjects (IDs).
>
> However, in my experiment a particular subject may have received both
> the treatment and placebo at the same or different dates (such as
> person of ID 2 and ID 1 respectively). This occurrence would then
> invalidate the experiment. I would then like to find a way to identify
> and flag those subjects.
>
> Date ID Received
> 1/1 1 Treatment
> 1/1 2 Treatment
> 1/1 2 Placebo
> 17/1 1 Placebo
> 18/1 3 Treatment
>
> I know I'd have to do bysort ID: gen flag = 1 if ...
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