Stata is not a time machine. Therefore, any version
of Stata cannot recognise features introduced in a later version.
You appear to be looking at some Stata 10 documentation
and using Stata 9.2. That can only lead to (occasional) confusion.
37200 is not a Stata daily date that could be part of your
data. You refer to Excel, which I understand to be a Microsoft
program. I know very little about it, but it may be that it
is using a base date that differs from Stata's, possibly 1 January 1900
rather than 1 January 1960. I would be careful, however,
as it is documented that Excel is incorrect about whether 1900
was a leap year, a case of bug-for-bug compatibility with Lotus 1-2-3.
Stata is correct on this point.
Otherwise the most developed (unofficial) solutions for date-time
manipulations in Stata 9.2 appear to be -ntimeofday-
and -stimeofday- published in the Stata Journal.
In Stata 9.2 you can set your date-times with unspecified
time unit. In your case that might need to be seconds.
You may need to worry about an appropriate display
format, or just not bother.
A better bet is to upgrade as soon as possible and make use
of Stata 10's facilities.
My program doesn't care about time units, so long as
your data are -tsset-.
Nick
[email protected]
Andrew Stocking
> Thank you for the program - it seems like a great solution! Two quick
> follow up question.
>
> My date variable is currently available down to the second (i.e.,
> -clocktime- to stata, though my 9.2 version of Stata doesn't
> recognize the
> -clocktime- option). Right now I have a string that appears:
> 11/5/2001 15:46
> or from Excel I've converted this to (I imagine stata can do the same,
> though it seems somewhat more complicated):
> 37200.6569
>
> I don't really care about the second or minutes or hours
> right now except
> that there are multiple contacts on the same day
> differentiated only by
> seconds, minutes, or hours. So, my two questions:
> 1) How do I set the date with hours, minutes, seconds as the
> time dimension
> of my panel data (-tsset-)? If I -trunc- off the h,m,s of the
> Excel-converted date, I receive the obvious error that there
> are "repeated
> time values within panel". It seems like the -clocktime-
> format should do
> it, but I get an error regarding clocktime as not recognized:
> -tsset Sent_Date, clocktime delta(1 day)-
> I've installed -egenmore- and read about the -dhms- function
>
> 2) What's the best way to deal with this with respect to your
> -count_recent-
> program below and the fact that I'll have two contacts in the
> same day? How
> do I set the lag to a whole day and have the program still
> accurately count
> totals?
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Nick Cox
> Sent: Sunday, July 22, 2007 2:00 PM
> To: [email protected]
> Subject: RE: st: Unbalanced panel, count number of incidents
>
> I don't see how Naomi's solution gets at the most
> difficult part of this problem, which is to take account
> of the irregularity of times observed in counting over
> the last # days.
>
> -egen, count()-, or even -egen, total()- which is a better
> bet for similar problems, is more or less useless for this
> kind of problem as the relevant time interval varies.
>
> I too am probably missing something simple. However,
> when all inspiration fails, try brute force.
> The brute force approach is quite easy to program
> and at worst requires a single loop over the observations.
>
> An approach discussed at length in
>
> Cox, N.J. 2007. Making it count. Stata Journal 7(1)
>
> is to set up a variable, loop over possibilities using
> -count- for each observation, and replace each value of that
> variable by the result.
>
> This is built into the following program:
>
> *! 1.0.0 NJC 22 July 2007
> program count_recent
> version 8
> syntax [if] [in], Lag(numlist int max=1 >0) Generate(str)
>
> quietly {
> confirm new var `generate'
>
> marksample touse
> count if `touse'
> if r(N) == 0 error 2000
>
> tsset
> local p "`r(panelvar)'"
> local t "`r(timevar)'"
> if "`p'" == "" {
> tempvar p
> gen byte `p' = 1
> }
>
> gen `generate' = .
>
> forval i = 1/`=_N' {
> if `touse'[`i'] {
> count if `touse' ///
> & inrange(`t'[`i'] - `t', 1, `lag') ///
> & `p' == `p'[`i']
> replace `generate' = r(N) in `i'
> }
> }
> }
> end
>
> What we are counting, for each observation, are
> how many observations are
>
> (c) in the same panel (whenever there is panel structure)
> -- you don't quite say this is what you want, but I guess
> it's true.
>
> (b) within 1 to -lag- (compulsory option) time units previous
>
> (a) relevant (by default all observations). This is determined
> by any -if- or -in- conditions.
>
> I assume a prior -tsset-.
>
> So, examples could be
>
> tsset ID Date
> count_recent , lag(30) generate(prev30)
> count_recent if Response == 1, lag(60) generate(pos_prev60)
>
> Nick
> [email protected]
>
> Naomi Levy
>
> > I am no expert here, and there is likely to be a much
> > easier way to do this than what I am suggesting, but this is what I
> > would do:
> >
> > I would -reshape- your data from long form to wide
> > form so that each row is an ID and the responses on each day
> > of contact
> > become separate variables.
> >
> > The new form would look like this:
> >
> > ID Response37200 Var137200 Var237200
> > Response37210 Var137210 Var237210
> > 1 1 1 1
> > 0 2 1
> >
> > Before
> > you do this I suggest dropping any variables you don't need for this
> > analysis and renaming variables so their names are shorter (e.g.
> > response to r). Also, if all you are interested in for the
> > analysis are more recent
> > dates of contact, you can drop all the data for prior dates
> > of contact.
> >
> > the syntax for reshape is:
> > reshape wide [varlist], i(id) j(date)
> >
> > once
> > you've done that, you can just generate a new variable that
> > sums across
> > the responses (once counting non-missing responses, and
> once counting
> > positive responses).
> >
> > after doing that, you can easily reshape the data back to long form:
> > reshape long [varlist], i(id) j(date)
>
> Andrew Stocking
>
> > I have an unbalanced panel of subjects who have been
> > contacted very
> > irregularly over the past 5 years. Total contacts range from
> > 40-250 during
> > the 5 year period depending on the person. I'd like to create two
> > variables: one that counts the total number of contacts in
> > the last 30 or 60
> > days and a second that sums the number of positive responses
> > over the same
> > 30 or 60 days. For each contact there could be anywhere from
> > 0-15 contacts
> > in the last 30 days.
> >
> > My data looks like:
> > ID Date Response Var1 Var2
> > 1 37200 1 1 1
> > 1 37210 0 2 1
> > 1 37215 1 3 2
> > 1 37229 1 4 3
> > 1 37231 0 4 2
> > 2 37201 0 1 0
> > .....
> >
> > I can't make egen count() work for me (or really anything else).
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