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# Re: st: shifting values one period ahead

 From Eric Booth To "" Subject Re: st: shifting values one period ahead Date Wed, 22 Sep 2010 23:35:18 +0000

```<>

On Sep 22, 2010, at 6:19 PM, Eric Booth wrote:

>> I am facing a tricky coding issue that involves creating 'newvar1'
>> from 'var1' given 'id' and 'start'.

The solution I proposed in the previous email creates the 'newvar1', but it does so in relation to 'id', not 'start'.  However, I don't see how 'start' impacts the creation of 'newvar1'.

For instance, in the second observation and the third observation 'newvar1' gets a 1 because 'var1' in the first and second observation gets a 1, but 'start' is 1 in the first observation and zero in the second observation yet the result for the creation of 'newvar1' is the same because it is based solely upon 'var1' by 'id'.  If there is some rule whereby 'newvar1' is created based on both 'id' and 'start', then there needs to be more explanation or clearer example data.

On Sep 22, 2010, at 6:19 PM, Eric Booth wrote:

> <>
>
>
> bys id : g newvar1 = var1[_n-1]
> replace newvar = 0 if mi(newvar1)
>
> EAB
>
> __
> Eric A. Booth
> Public Policy Research Institute
> Texas A&M University
> ebooth@ppri.tamu.edu
>
>
> On Sep 22, 2010, at 6:13 PM, asb stata wrote:
>
>> I am facing a tricky coding issue that involves creating 'newvar1'
>> from 'var1' given 'id' and 'start'. The variable 'newvar1' is obtained
>> by shifting 'var1' one period ahead within each 'id'.
>>
>> id	start	var1	newvar1
>>
>> 1	1	1	0
>> 1	0	1	1
>> 1	0	0	1
>> 1	0	0	0
>>
>> 2	0	0	0
>> 2	0	0	0
>> 2	1	1	0
>> 2	0	0	1
>> 2	0	1	0
>>
>> 3	0	0	0
>> 3	0	0	0
>> 3	1	1	0
>> 3	0	1	1
>> 3	0	1	1
>> *
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>> *   http://www.ats.ucla.edu/stat/stata/
>
>
>
>
> *
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```