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Re: st: getting Stata to read a bizarre sequence of dates


From   stef salvez <loggyedy@googlemail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: getting Stata to read a bizarre sequence of dates
Date   Fri, 15 Jun 2012 18:01:59 +0200

thank you NIck very much for one more time. (the problem with my pc
has been resolved  and am back with my proper name again)

Again, i reallly thank you

On 6/13/12, Nick Cox <n.j.cox@durham.ac.uk> wrote:
> There are no contradictions here. Many dates round to the same value of
> floor(dailydate/28). The rounded date does not remember what it was
> originally.
>
> tsfill- only adds observations with missing values at times that were gaps.
> It does not interpolate.
>
> Nick
> n.j.cox@durham.ac.uk
>
> joales salbdralor
>
>
> Thank you for your reply on my question
> I want to comment on two things
>
> 1)	You mentioned that
>  " There is a gap
> at 638 as the following reveals.
>
> . format edate1 %td
>
> . tab edate1
>
>     edate1 |      Freq.     Percent        Cum.
> ------------+-----------------------------------
>  23nov2008 |          2       14.29       14.29
>  28dec2008 |          2       14.29       28.57
>  25jan2009 |          2       14.29       42.86
>  22feb2009 |          2       14.29       57.14
>  29mar2009 |          2       14.29       71.43
>  26apr2009 |          2       14.29       85.71
>  24may2009 |          2       14.29      100.00
> ------------+-----------------------------------
>      Total |         14      100.00
>
> . tab edate2
>
>     edate2 |      Freq.     Percent        Cum.
> ------------+-----------------------------------
>        637 |          2       14.29       14.29
>        639 |          2       14.29       28.57
>        640 |          2       14.29       42.86
>        641 |          2       14.29       57.14
>        642 |          2       14.29       71.43
>        643 |          2       14.29       85.71
>        644 |          2       14.29      100.00
> ------------+-----------------------------------
>      Total |         14      100.00
>
> But there is also another gap of 35 days going from 22/02/09 to
> 29/03/09 which is not taken into account by the above table. Why is
> this the case?
> You can see the same problem by looking at the data editor after having
> typed
>
> gen edate1 = date(dates1, "DM20Y")
> gen edate2 = floor(edate1/28)
> tsset id edate2
> tsfill, full
>
> 2)  My opinion is that by using the -tsfill, full-  as a solution to
> "fix" the gap problem I do not gain much because even if I issue the
> commands
>
> gen edate1 = date(dates1, "DM20Y")
> gen edate2 = floor(edate1/28)
> tsset id edate2
> tsfill, full
> egen nonmiss = rownonmiss(id)
>
> and base my analysis on  ..if rownonmiss(2) nothing will change. I
> just sort out the data in a more clear way. As you mentioned,
> interpolation may be the best solution
>
> thanks again
>
>
> On 6/13/12, Nick Cox <njcoxstata@gmail.com> wrote:
>> If "joales salbdralor" is really "stef salvez" what is going on? Do
>> note the firm request that Statalist posters use their real names.
>>
>> If you have gaps in your data, most commands can cope. There is no
>> catch-all solution, as whether gaps are a problem depends on what you
>> want to do. Some kind of interpolation would be necessary for some
>> commands to be used.
>>
>> Nick
>>
>> On Wed, Jun 13, 2012 at 8:31 AM, joales salbdralor
>> <joalessakafiora@googlemail.com> wrote:
>>> thanks Nick for your reply. you are right (as always) that  Stata can
>>> read these   string dates and it is converting them to numeric dates.
>>> The only problem that I have is how to avoid having the "with gaps"
>>> comment, Put differently, how can I correct this problem?. Or is it ok
>>>  by just issuing the previously mentioned commands,  that is:
>>>
>>> gen edate1 = date(dates1, "DM20Y")
>>> gen edate2 = floor(edate1/28)
>>> tsset id edate2
>>>
>>>
>>> Regarding your reasonable question why I am posting  mysteriously
>>> similar questions is that I want to play around with different and
>>> "bizarre" sequence of dates as this is the first step if I want to
>>> start doing correct data/econometric analysis .
>>>
>>>
>>>
>>> thank you very much again
>>>
>>>
>>> On 6/13/12, Nick Cox <njcoxstata@gmail.com> wrote:
>>>> You've posted numerous questions on this kind of data over the last
>>>> few weeks, to which there have been numerous answers, so why you ask
>>>> this question seems especially mysterious.
>>>>
>>>> First, Stata _is_ reading your string dates and it _is_ converting
>>>> them to numeric dates. So the implication that Stata can't read these
>>>> data is quite wrong.
>>>>
>>>> The only problem evident is that there is one gap in this dataset even
>>>> when you restructure it as a series with spacing 28 days.
>>>>
>>>> So, what -tsset- reports is essentially "fair comment". There is a gap
>>>> at 638 as the following reveals.
>>>>
>>>> . format edate1 %td
>>>>
>>>> . tab edate1
>>>>
>>>>      edate1 |      Freq.     Percent        Cum.
>>>> ------------+-----------------------------------
>>>>   23nov2008 |          2       14.29       14.29
>>>>   28dec2008 |          2       14.29       28.57
>>>>   25jan2009 |          2       14.29       42.86
>>>>   22feb2009 |          2       14.29       57.14
>>>>   29mar2009 |          2       14.29       71.43
>>>>   26apr2009 |          2       14.29       85.71
>>>>   24may2009 |          2       14.29      100.00
>>>> ------------+-----------------------------------
>>>>       Total |         14      100.00
>>>>
>>>> . tab edate2
>>>>
>>>>      edate2 |      Freq.     Percent        Cum.
>>>> ------------+-----------------------------------
>>>>         637 |          2       14.29       14.29
>>>>         639 |          2       14.29       28.57
>>>>         640 |          2       14.29       42.86
>>>>         641 |          2       14.29       57.14
>>>>         642 |          2       14.29       71.43
>>>>         643 |          2       14.29       85.71
>>>>         644 |          2       14.29      100.00
>>>> ------------+-----------------------------------
>>>>       Total |         14      100.00
>>>>
>>>> By the way, posting code that others can run is an excellent idea, but
>>>> cut the -cd d:- which assumes that users have a d: drive, which may be
>>>> quite wrong.
>>>>
>>>> Nick
>>>>
>>>> On Wed, Jun 13, 2012 at 12:37 AM, stef salvez <loggyedy@googlemail.com>
>>>> wrote:
>>>>
>>>>> I have the following panel data set
>>>>>
>>>>>  clear all
>>>>> cd d:\
>>>>> input str8  (dates1)            id
>>>>>  "23/11/08"         1
>>>>> "28/12/08"          1
>>>>>  "25/01/09"        1
>>>>>  "22/02/09"         1
>>>>> "29/03/09"         1
>>>>>  "26/04/09"        1
>>>>>  "24/05/09"        1
>>>>>  "23/11/08"         2
>>>>> "28/12/08"          2
>>>>>  "25/01/09"        2
>>>>>  "22/02/09"        2
>>>>> "29/03/09"         2
>>>>>  "26/04/09"        2
>>>>>  "24/05/09"        2
>>>>>
>>>>> end
>>>>>
>>>>> the difference (in days)  between successive dates is 35 28 28 35 28
>>>>> 28
>>>>>
>>>>> The problem is that I do not know how to convert these string dates
>>>>> into numeric variables given the fact that I have 2 jumps  (35 days)
>>>>>  if i issue the commands
>>>>>
>>>>> gen edate1 = date(dates1, "DM20Y")
>>>>> gen edate2 = floor(edate1/28)
>>>>> tsset id edate2
>>>>>
>>>>> I get the following error message
>>>>>
>>>>> panel variable:  id (strongly balanced)
>>>>>        time variable:  edate2, 637 to 644, but with gaps
>>>>>                delta:  1 unit
>>>>>
>>>>> Is there any code that could fix that so as to get Stata to "read"
>>>>> that "bizarre"sequence of dates?
>>
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