Re: st: how to generate row mode

[David Kantor <kantor.d@att.net>]

At 10:12 AM 1/23/2008, Fernando wrote:
> Hello
>
> I am trying to compute the equivalent to a rowmode, a function 
> similar to rowmean in the egen command. i think the ado for a 
> rowmode function (which may compute the mode across several 
> variables) does not exist, does it? as an alternative i thought to 
> reshape the data and collapse it using the mode but the mode is not 
> a function to collapse the data.
> is there a way to compute the mode across a set of variables for each subject?
> [...]
I don't know of any such routine or function. And I suspect it is 
very hard to program it in Stata directly. Perhaps it is somewhat 
easier in mata. (?)

I would also warn you that the mode is potentially an ambiguous 
calculation; you need a tie-breaking decision rule. E.g., suppose 
your values are 3,3,4,4; what's the mode?

Putting that aside, I might suggest that you reshape your data into 
long form; then take the mode using the egen mode function; then 
reshape back to wide (or just select one record per 
unit-of-observation). The egen mode function has several options for 
tie-breaking. (I also have an alternative variant for yet another 
tie-breaking option -- to take the latest-occurring value.)

I hope this helps.
--David




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