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# Re: st: how to get monthly values from Bimonthly data

 From sabbas gidarokostas To statalist@hsphsun2.harvard.edu Subject Re: st: how to get monthly values from Bimonthly data Date Fri, 3 Aug 2012 00:39:25 +0100

```Thank you Nick. I suppose that when you say double up you mean to
divide by 2. Am I right?

The data that I have are stocks  rather than flows. So, I have to

thanks

On 7/31/12, Nick Cox <njcoxstata@gmail.com> wrote:
> That wasn't clear.
>
> So, you will need to double up. If monthly dates go up in steps of 2
>
> expand 2
> bysort date : replace date = date + 1 if _n == 2
>
> On Tue, Jul 31, 2012 at 12:45 PM, sabbas gidarokostas
>> thanks Nick for your reply and the useful code. But I need to convert
>> these values to monthly data because the rest of my data are only
>> monthly  values.
>>
>> cheers
>>
>> On 7/31/12, Nick Cox <njcoxstata@gmail.com> wrote:
>>> I would leave these data almost as they are. What you can do is
>>>
>>> gen year = real(substr(dates, -4, 4))
>>> gen period = substr(dates, 1, 2)
>>> gen month = cond(per == "JF", 1, cond(per == "MA", 3, cond(per ==
>>> "MJ", 5, cond(per == "JA", 7, cond(per == "SO", 9, cond(per == "ND",
>>> 11, .))))))
>>>
>>> gen date = ym(year, month)
>>> tsset id date , delta(2)
>>>
>>> The key point is that you have bimonthly data and that's fine. No
>>> doubling up or interpolation is needed; in fact that can only produce
>>> a spurious increase in your sample size.
>>>
>>> Some people would undoubtedly prefer -recode- for the mapping "JF" -> 1,
>>> etc.
>>>
>>> Nick
>>>
>>> On Fri, Jul 27, 2012 at 3:48 AM, sabbas gidarokostas
>>>> Dear all,
>>>>
>>>> I have the following panel data set
>>>> clear all
>>>> input str8  (id        text             dates           values1
>>>> values2 )
>>>>
>>>> "1"    "ot"            " "             ""                " "
>>>> "1"    "wt"          " "               ""              " "
>>>> "1"    "rt"        "MA 2005"            "32.4"          "2.5"
>>>> "1"    "gh"        "MJ 2005"            "82.3"          "12.5"
>>>> "1"    "bg"        "JA 2005"            "2.5"          "24.5"
>>>> "1"    "se"        "SO 2005"            "82.5"          " "
>>>> "1"    "cv"        "ND 2005"            "62.3"          "26.3"
>>>> "1"    "cv"        "JF 2006"           "12.2"           "22.3"
>>>> "1"    "cv"        "MA 2006"            "22.1"          "2.4"
>>>> "2"    "ot"          " "                " "               " "
>>>> "2"    "wt"           " "                " "         " "
>>>> "2"    "rt"        "MA 2005"
>>>> "2"    "gh"         "MJ 2005"            "32.3"          "23.5"
>>>> "2"    "bg"        "JA 2005"            "52.4"          "22.3"
>>>> "2"    "se"        "SO 2005"            "82.9"          "22.5"
>>>> "2"    "cv"        "ND 2005"            " "          "2.5"
>>>> "2"    "cv"        "JF 2006"            "332.4"          " "
>>>> "2"    "cv"        "MA 2006"            "312.4"          "21.5"
>>>> end
>>>> The above data set is a sample.
>>>> Basically,I have 30000 individuals and  instead of the last 2 columns
>>>> that contain the numbers I have 29 such columns.
>>>>
>>>> The data set refers to bimontly values.
>>>>
>>>> Is there a way to  convert the above data to montly data?
>>>> Specifically, What I think is that first I have to split the dates as
>>>> follows
>>>>
>>>> M/2005
>>>> A/2005
>>>> M/2005
>>>> J/2005
>>>>
>>>> and so forth and then to convert them to
>>>>
>>>> 3/2005
>>>> 4/2005
>>>> 6/2005
>>>> and so forth.
>>>>
>>>> So regarding the first 3 columns I should get
>>>>
>>>> "1"    "ot"            " "
>>>> "1"    "wt"          " "
>>>> "1"    "rt"        "3/2005"
>>>> "1"    "rt"        "4 2005"
>>>> "1"    "gh"        "5/2005"
>>>> "1"    "gh"        "6/2005"
>>>>
>>>> and so forth.I am not exactly sure how to handle the last two columns,
>>>> though(numerical values)
>>>>
>>>> I think that one way would be to divide the bimonthly values by 2. Then
>>>> I
>>>> get
>>>>
>>>> "1"    "ot"            " "
>>>> "1"    "wt"          " "
>>>> "1"    "rt"        "3/2005"            "32.4/2"          "2.5/2"
>>>> "1"    "rt"        "4 2005"              "32.4/2"          "2.5/2"
>>>> "1"    "gh"        "5/2005"             "82.3/5"          "12.5/5"
>>>> "1"    "gh"        "6/2005"                  "82.3/5"          "12.5/5"
>>>>
>>>> I am not sure that this makes sense as I have repeated values for two
>>>> consequtive months.
>>>>
>>>> Another way would be interpolation?
>>>>
>>>> Any code provided is greatly appreciated.
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```