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From | Doug Hess <douglasrhess@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: replacing missing time period data with next closest period |
Date | Wed, 16 Mar 2011 12:02:26 -0400 |
Hi. I'm hoping there are a set of commands that will help me edit cells for this missing data problem. Each row in my dataset is a month for each state (and DC) over five years (i.e., 51x5x12= 3,060 rows). The columns are binary values for the reported presence of a policy that some states in some months have implemented and others have not. Unfortunately, the months in which states report the existence (or not) of the policy option varies by year, and only the months when the option is reported have been coded. Thus, a state that reports not having selected a policy option in April 2001 and then reports adopting the policy in August 2001, with no reports in between, would have the value of 0 for April and 1 for August, but missing "." for the other 10 months of the year (i.e., missing until the next report). I would like to fill in the months in between reports with the value of the next closest month that has a value, and default to zero if the missing month is equidistant to a 0 or 1. I.e., in the example above, assuming the policy had not changed before or after these reported months, the cells from January thru June = 0, July thru December= 1. I'm starting to think I'll just do this by hand, but I wonder if there's some nifty "if then...do" routine that can be created as I would like to add more years and do this for a large number of policy variables. If it matters: I'm using Stata 11 and don't have Stata programming language experience (as opposed to issuing commands). My computer programming skills stopped circa 1982 when I learned Basic on an Apple IIe. So, if there's a choice between clunky commands and elegant programming with the same results, I might go for the clunky commands. But I am happy to learn if there's a resource I need to consult to understand any advice or tips that are provided. Thank you. Doug * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/