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


From   Nick Cox <njcoxstata@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: how to get monthly values from Bimonthly data
Date   Fri, 3 Aug 2012 00:44:24 +0100

No; I mean -expand 2- as I said.

On 3 Aug 2012, at 00:39, sabbas gidarokostas <sabbasgidarokostas@googlemail.com > wrote:

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
interpolate instead of spliting.

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
<sabbasgidarokostas@googlemail.com> wrote:
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
<sabbasgidarokostas@googlemail.com> wrote:
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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