RE: st: dividend programming question

["Khieu, Hinh" <Hdkhieu@usi.edu>]

Nick,

Thanks so much for your prompt help.

Here's what I meant for question #2: Let's say I have firm A and firm B below. I want to create a binary variable called Omission. Firm B has dots, but Firm A do not have any records for div paid from 1997-2001.
FirmA                    Div paid	Omission 
1995                     .10		0
1996                     .10		1
2002                     .15		0
2003                     .15		0
2004                     .15		0
2005                     .10		0
2006                     .10		0
2007                     .10		0
2008                     .10		0
2009                     .12		0
2010                     .12		0
2011                     .12		0
2012                     .15		0
FirmB                 Div paid		Omission
1995                     .10		0
1996                     .10		0
1997		.		1
1998		.		1
1999		.		1
2000		.		1
2001		.		1
2002                     .15		0
2003                     .15		0
2004                     .15		0
2005                     .10		0
2006                     .10		0
2007                     .10		0
2008                     .10		0
2009                     .12		0
2010                     .12		0
2011                     .12		0
2012                     .15		0

Again, I really appreciate any help here.

Regards,
Hinh
-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
Sent: Saturday, March 23, 2013 2:29 PM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: dividend programming question

#1. Given

firmid year dividend

the first year when -dividend- > 0 is

egen yearfirstpaid = min(year / (dividend > 0)), by(firmid)

and so an indicator for first year is

gen wasfirst = year == yearfirstpaid

#2. Not clear to me. You seem to be saying both that you do and do not have observations for certain years. Please review Stata terminology:

an observation is a record, case, or row (and _not_ a value)

a value is the value of a variable

missing values are present in the data, but missing

If observations are not present in the data, they are (in my view) better called "omitted" or "not present".

See -help fillin- as a first step.

Nick

On Sat, Mar 23, 2013 at 6:45 PM, Khieu, Hinh <Hdkhieu@usi.edu> wrote:

> I have an unbalanced time series data: firm ID, year, and annual 
> dividend amount. I want to create 2 binary variables
>
>
>
> 1/  indicating when firm A pays dividends for the first time. Firms 
> may enter the dataset and pay div for the first time right at the 
> first data entry (example: firm A first appears in data 1990 and pays 
> div in 1990, and the variable should be 1 for 1990 and zero for other 
> years. Firms may enter the data set and do not pay any div until 5 
> years later (example: first appear in data 1990 and pay div in 1995, 
> and dummy should be 1 for 1995 and zero for other years.) What makes 
> it complicated is that firms may skip paying div for some years and 
> come back starting to pay div again. The same binary variable should 
> be 1 if the firm does not pay div for 5 years and starts repaying div 
> in year 6 (example: first appear in data 1990 and pay div in 1995, and 
> dummy should be 1 for 1995 and firm does not pay any div in years 1996 
> through 2001 and starts paying div in 2002, dummy should be zero for 
> 1996-2001 and 1 for 2002 and zero for other years.)
>
>
>
> 2/ the second dummy captures the omission of dividends above. If firm A pays div in 1995-1996, stops paying from 1997-2001, and pays again 2002 to 2013, dummy should be zero for 1995-1996, one for 1997-2001, and zero again 2002-2013. The problem is that sometimes observations for 1997-2001 are just dots, sometimes the observations are like this (year 1997-2001 are not there):
>
> FirmA                    Div paid
>
> 1995                     .10
>
> 1996                     .10
>
> 2002                     .15
>
> 2003                     .15
>
> 2004                     .15
>
> 2005                     .10
>
> 2006                     .10
>
> 2007                     .10
>
> 2008                     .10
>
> 2009                     .12
>
> 2010                     .12
>
> 2011                     .12
>
> 2012                     .15
>
>
>
> In this case, I want the omission dummy to be 1 in year 1996.

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