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Problem with dates in the Ethiopia datasets [message #66] Wed, 20 February 2013 11:19 Go to next message
DHS user is currently offline  DHS user
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The variables in the Ethiopia datasets, related to the year of the study do not match the actual timing of the study. Is this an error?
Re: Problem with dates in the Ethiopia datasets [message #67 is a reply to message #66] Wed, 20 February 2013 11:28 Go to previous messageGo to next message
Bridgette-DHS is currently online  Bridgette-DHS
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All standard date variables in the Ethiopia data file are in the Ethiopian calendar. In general the Ethiopian calendar is 92 months behind the Gregorian (western) calendar. The Ethiopian year runs from September 11 through September 10 and has 12 months of 30 days and 1 months of 5 days. Thus it is only possible to transfer the Ethiopian calendar into the Gregorian calendar when the exact date (day, month and year) is available. Therefore, in the file you will find additional variables indicating the Gregorian dates if they could be established.

Note that all standard variables based on calendar dates and century month codes are given in the Ethiopian Calendar. In general, the Ethiopian year consists of 365 days, divided into 12 months of 30 days and one month of 5 days (6 days in a leap year). Ethiopia's new year falls on September 11and ends the following September 10 according to the Gregorian calendar. From September 11 to December 31, the Ethiopian year runs seven years behind the Gregorian year, thereafter, the difference is eight years. Since the exact day is not available for most dates, it is not possible to convert the dates exactly, but only approximate it to the month. There is a difference of 92 months between the two date systems. The 13th month of the Ethiopian calendar falls in September. Thus, to keep the higher precision available in the Ethiopian calendar, these were used for all standard recode variables where applicable. In general, dates in the Gregorian calendar are provided as country specific variables. However, the calendar is transferred to the Gregorian calendar.

To explain somewhat further, the number of months in the CMC variables (even for Ethiopian dates) are computed as follows: each year has 12 months, but when the event was in the 13th month then 13 is added for the number of months. Thus e.g. a person was born in the 13th month of 1960 in the Ethiopian calendar, then the CMC is 60 * 12 + 13. Thus the 5 days in the 13th month really go to the following year when you recomputed the CMC back to years (with 12 months). But this will cause little bias. So just use the CMC as you would for other surveys (intervals should not be divided by 13, but by 12). However, know that on average the Ethiopian calendar lags 92 months behind our Gregorian system.

The Ethiopian calendar was kept as the standard variables, sinceĀ  not all dates (e.g. vaccination dates) could be transferred.

Here is a link that you can use to convert Ethiopian dates:

http://www.funaba.org/en/calendar-conversion.cgi

Attached is a little Stata script: "ETcalconvert", that you may find useful (written by DHS Data User: Keith Kranker).

I hope this helps.

Bridgette-DHS

[Updated on: Mon, 18 March 2013 09:14]

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Re: Problem with dates in the Ethiopia datasets [message #8980 is a reply to message #67] Fri, 22 January 2016 12:02 Go to previous messageGo to next message
lillo?S is currently offline  lillo?S
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Hello,

From what I can see in the DHS 2005 there are country-specific variables that define the dates in the Gregorian calendar, the same does not hold for DHS 2011.

In the 'Individual Recode Documentation' (p.8) I find this:

"Before the production of any indicators with these data the Ethiopian calendar was converted to the Gregorian calendar but conserving the Ethiopian year; however, the Ethiopian first month is considered in the logic as January, the 2nd as February, etc. For dates including year, month and day the conversion is precise since both calendars have 365 or 366 days; for dates including only year and month, the 13th month was included in December."

I understand that the months have already been converted, whereas the years have not.
When I go to the 'CSPRO Process Summary' file and look at v006, the months of interview range from 4 through 9. According what's written in the IRD word file, I should interpret this as 4=April and 9=September because the conversion is supposed to have been already done. However, in the website at http://dhsprogram.com/what-we-do/survey/survey-display-359.c fm I see that: Fieldwork: December 2010 - May 2011. These months do not match the ones above, whereas they could coincide if the conversion had not been done.

My questions are:

1- has the conversion been done or not?
2- how are the CMC variables given?

Thanking you in advance.
Re: Problem with dates in the Ethiopia datasets [message #8981 is a reply to message #67] Fri, 22 January 2016 12:04 Go to previous messageGo to next message
lillo?S is currently offline  lillo?S
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Hello,

From what I can see in the DHS 2005 there are country-specific variables that define the dates in the Gregorian calendar, the same does not hold for DHS 2011.

In the 'Individual Recode Documentation' (p.8) I find this:

"Before the production of any indicators with these data the Ethiopian calendar was converted to the Gregorian calendar but conserving the Ethiopian year; however, the Ethiopian first month is considered in the logic as January, the 2nd as February, etc. For dates including year, month and day the conversion is precise since both calendars have 365 or 366 days; for dates including only year and month, the 13th month was included in December."
I understand that the months have already been converted, whereas the years have not.

When I go to the 'CSPRO Process Summary' file and look at v006, the months of interview range from 4 through 9. According what's written in the IRD word file, I should interpret this as 4=April and 9=September because the conversion is supposed to have already been done. However, in the website at http://dhsprogram.com/what-we-do/survey/survey-display-359.c fm I see that: Fieldwork: December 2010 - May 2011. These months do not match the ones above, whereas they could coincide if the conversion had not been done.

My questions are:

1- has the conversion been done or not?
2- how are the CMC variables given?

Thanking you in advance.
Re: Problem with dates in the Ethiopia datasets [message #9035 is a reply to message #8981] Fri, 29 January 2016 12:56 Go to previous messageGo to next message
Bridgette-DHS is currently online  Bridgette-DHS
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Following is a response from Senior DHS Stata Specialist, Tom Pullum:

In the 2011 survey, all dates are in the Ethiopian calendar rather than the Gregorian calendar. The cmc is also calculated consistently with the Ethiopian calendar. For example, you can confirm that v008=12(v007 1900) + v006. This consistency is found in all surveys, whether using the Gregorian, Ethiopian, or Nepalese calendars.

To convert to the Gregorian calendar, add 92 to the Ethiopian cmc. Then get the Ethiopian year and month from the Ethiopian cmc as follows, illustrated again for v006, v007, and v008:

gen v007=int((v008-1)/12)
gen v006=v008-12*v007
replace v007=v007+1900
Re: Problem with dates in the Ethiopia datasets [message #9179 is a reply to message #9035] Fri, 19 February 2016 10:12 Go to previous messageGo to next message
st89
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A follow-up question about the dates in the 2011 survey (specifically the children's recode): variable h9d (day of month of measles vaccination, if known) takes on values from 1 to 31. However, my understanding is that all of the dates are in the Ethiopian calendar, which should have 12 months of 30 days + one month of 5 or 6 days. I'm unclear on how to use h9d values of 31 since it is not in the Ethiopian calendar, and am thus not able to convert the three variables h9y-h9m-h9d to Gregorian dates.

Thanks for your help!
Re: Problem with dates in the Ethiopia datasets [message #9183 is a reply to message #9179] Fri, 19 February 2016 12:02 Go to previous messageGo to next message
Bridgette-DHS is currently online  Bridgette-DHS
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Another response from Tom Pullum:

I will start by repeating an answer I gave on the forum on January 29, but this time with a correction of a typo in the January 29, version, where in the second paragraph I said "Ethiopian" but meant "Gregorian"--sorry about that.

In the 2011 survey, all dates are in the Ethiopian calendar rather than the Gregorian calendar. The cmc is also calculated consistently with the Ethiopian calendar. For example, you can confirm that v008=12(v007 1900) + v006. This consistency is found in all surveys, whether using the Gregorian, Ethiopian, or Nepalese calendars.

To convert to the Gregorian calendar, add 92 to the Ethiopian cmc. Then get the Gregorian year and month from the Gregorian cmc as follows, illustrated again for v006, v007, and v008. I will use vg006, etc, to indicate that these are Gregorian versions of the original Ethiopian codes.

gen vg008=v008+92
gen vg007=int((vg008-1)/12)
gen vg006=vg008-12*v007
replace vg007=vg007+1900

Now to get to your question. Although you may be right that there is a 5-day month in the Ethiopian calendar, I think it must be absorbed in one or both of the adjacent months. If you go to the BR file and enter "tab h9m" or "tab b2", etc., you will see 12 numbered months, all with about the same number of cases. I recommend that you simply do the month and year conversion described above, but keep the day as h9d. I would look at how the days 29, 30, and 31 are converted to a day with "day=mdy(h9m,h9d,h9y)". You will find that certain combinations of year and month and day (even year, because of Leap Year) are rejected, and will produce "day=." because the specified Gregorian month has only 30 days, or in the case of February has only 28 days, except in a Leap Year, when it has 29! (Ten days from now we will have a Feb. 29!) Then I personally would recode h9d for all of the rejected values to 28, but you could go to more trouble and successively convert to 30, then to 29, then to 28, until all combinations of year, month, and day are accepted. The kind of error that will be incurred with this sort of adjustment will be trivial, especially compared with other reporting errors.

Re: Problem with dates in the Ethiopia datasets [message #13551 is a reply to message #9183] Fri, 17 November 2017 12:39 Go to previous messageGo to next message
kcaglaya@tulane.edu is currently offline  kcaglaya@tulane.edu
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Hi,

I use b1 (month of birth) and hw16 (day of birth of child) in my analysis and initially assumed that both of these information are provided according to the Ethiopian calendar. However, as mentioned before in the forum; hw16 takes the values from 1 to 31 in 2011 and 2016 Surveys. (In 2000 and 2005 max value for hw16 is 30) I looked at the months in which hw16 is equal to 31 and this is how it looks like:

. tab b1 if hw16==31

month of |
birth | Freq. Percent Cum.
------------+-----------------------------------
1 | 37 24.03 24.03
3 | 21 13.64 37.66
5 | 25 16.23 53.90
7 | 19 12.34 66.23
8 | 30 19.48 85.71
10 | 16 10.39 96.10
12 | 6 3.90 100.00
------------+-----------------------------------
Total | 154 100.00

These are the Gregorian months with 31 days. Does this mean that b1 (month of birth) is also in Gregorian calendar? Also see the months with 30 and 31 days:

. tab b1 if hw16==31 | hw16==30

month of |
birth | Freq. Percent Cum.
------------+-----------------------------------
1 | 73 14.07 14.07
3 | 52 10.02 24.08
4 | 32 6.17 30.25
5 | 67 12.91 43.16
6 | 38 7.32 50.48
7 | 72 13.87 64.35
8 | 59 11.37 75.72
9 | 27 5.20 80.92
10 | 52 10.02 90.94
11 | 26 5.01 95.95
12 | 21 4.05 100.00
------------+-----------------------------------
Total | 519 100.00

It lacks February as we expect from the Gregorian Calendar.

My conversion from Ethiopian to Gregorian calendar depends on b1. I would greatly appreciate a clarification regarding the variable b1.

Regards,

Koray Caglayan
Re: Problem with dates in the Ethiopia datasets [message #13746 is a reply to message #13551] Mon, 18 December 2017 12:26 Go to previous messageGo to next message
Bridgette-DHS is currently online  Bridgette-DHS
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Following is a response from Senior Data Processing Specialist, Ladys Ortiz:

Birth Month and Day Variables in DHS Ethiopian Household Survey

Your Comments: We use B1 (month of birth) and HW16 (day of birth of child) in our analysis and initially assumed that both of these variables are reported according to the Ethiopian calendar. However, HW16 takes values from 1 to 31 only in 2011 and 2016 Surveys. (In 2000 and 2005 the max value for HW16 is 30) We looked at the months in which HW16 is equal to 31 and this is what it looks like:

Response:
A) FYI: For the date of birth of the child you should use DD=B17/MM=B1/YY=B2; variable HW16 is for children with Height/weight.
B) One of the differences between EDHS 2016 and previous DHS's is that the DAY of birth of the child was included in the birth history (DD/MM/YYYY) instead of MM/YYYY, as in prior surveys. Because of that we could convert the day and the month of birth to Gregorian calendar but the year remains as Ethiopian calendar.
C) You will find more information about how Ethiopian's dates were processed for previous surveys by checking the recode documentation included in our website.

Hope my response helps in answering your questions.

Ladys
Re: Problem with dates in the Ethiopia datasets [message #13747 is a reply to message #13746] Mon, 18 December 2017 13:21 Go to previous messageGo to next message
kcaglaya@tulane.edu is currently offline  kcaglaya@tulane.edu
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Dear Ladys,

Thank you so much for your response. It helps a lot.
There is one more thing that I would like to be sure of, since the results of our analysis heavily depend on the day of birth.

1) b17 is identical with hw16 in 2016 survey. We are using hw16 since it is present in the data across all survey years. We pool the data from all survey years in our estimations. Height and weight are among our variables of interest, so we are using observations with height and weight variables available anyway.

2) The information you provided about 2016 survey in terms of birth day and birth month is very helpful and answers our question. However, we suspect that this might also be the case for 2011 survey; i.e. hw16 and b1 are also reported in Gregorian Calendar in 2011 survey. I base this on the fact that in 2011 survey data; hw16 varies between 1-31, the birth months with hw16=31 are the Gregorian months with 31 days and also birth months with hw16=30 or hw16=31 lack February as we would expect from Gregorian Calendar. So, I would greatly appreciate if you can confirm whether the following table regarding the way these dates are reported is correct or not. I also attach the table as a separate file.

B17 (Day of Birth) HW16 (Day of Birth) B1 (Month of Birth) B2 (Year of Birth)
2000 Survey - Ethiopian Ethiopian Ethiopian
2005 Survey - Ethiopian Ethiopian Ethiopian
2011 Survey - Gregorian Gregorian Ethiopian
2016 Survey Gregorian Gregorian Gregorian Ethiopian

Once again, thank you for your time and help.

Regards,

Koray

[Updated on: Mon, 18 December 2017 13:23]

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Re: Problem with dates in the Ethiopia datasets [message #13748 is a reply to message #13747] Mon, 18 December 2017 17:15 Go to previous messageGo to next message
Bridgette-DHS is currently online  Bridgette-DHS
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Another response from Ladys Ortiz:

Dear Koray,

I forwarded your email to the Data Processing Specialist who processed EDHS-2005, so he can address your questions. Hopefully, it will be sooner than later (there could be delays as many of us are already on vacation for the holidays).

Thanks,

Ladys Ortiz

Re: Problem with dates in the Ethiopia datasets [message #13754 is a reply to message #13748] Tue, 19 December 2017 14:31 Go to previous messageGo to next message
Bridgette-DHS is currently online  Bridgette-DHS
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Following is a response from Senior DHS Data Processing Manager, Albert Themme:

I checked the imputation and recode programs for 2000 and 2005. Both handled the construction of HW16, B1 and B2 in the same way.

As the recode documentation states all dates are in the Ethiopian calendar.
Thus in 2000 HW16 was derived from HC16, which is a copy of QHC29D as recorded on the questionnaire.
Similarly, in 2005 HW16 was derived from HC16, which is a copy of QC53D again as recorded on the questionnaire.

B1 and B2 are derived from B3 (CMC data of birth of child) with is a copy of Q215C. The computation of Q215C had one difference from our standard procedure. The Ethiopian month and year of birth were used, but when the month of birth was recorded as 13, then 13 months were added to the last year.

E.g. the child was born 13 1960, then the CMC is computed as 60 * 12 + 13.
When the year and month of birth are then returned from this CMC, then the 13th month is really added to the 1st month of the new year.

Let me know if this is not clear.
Re: Problem with dates in the Ethiopia datasets [message #13755 is a reply to message #13754] Tue, 19 December 2017 14:50 Go to previous messageGo to next message
kcaglaya@tulane.edu is currently offline  kcaglaya@tulane.edu
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Dear Bridgette, Ladys and Albert,

Thank you so much for your time and help. We greatly appreciate your kind effort.
We are very close to clarify this issue completely. I just need your help and expertise on one last thing. (at least for this project :))

Yesterday, Ladys confirmed that a child's day of birth (b17 or hw16) and month of birth (b1) are reported in Gregorian Calendar while the year of birth (b2) is reported in Ethiopian Calendar in 2016 survey data.

Today, Albert confirmed that a child's day (hw16), month (b1) and year (b2) of birth are all reported in the same way and in Ethiopian Calendar in 2000 and 2005 survey data.

If somebody can confirm the way these variables (i.e. hw16, b1, b2) are reported in 2011 survey data, we would be able to solve the problem completely.

I think, in 2011 these variables are reported as they are reported in 2016 (i.e. hw16 and b1 in Gregorian Calendar and b2 in Ethiopian Calendar) because of the reasons that I mentioned in previous posts. However, I would really appreciate a confirmation from you on this matter.

Once again, thank you very much.

Regards,

Koray




Re: Problem with dates in the Ethiopia datasets [message #13757 is a reply to message #13755] Tue, 19 December 2017 16:31 Go to previous messageGo to next message
Bridgette-DHS is currently online  Bridgette-DHS
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Another response from Ladys Ortiz:

As recommended in my previous email, you should read the recode documentation that we usually post within the zipped dataset. The following is excerpted from the documentation mentioned earlier, and hopefully, this answers your question:

Quote:
All standard variables are based on calendar dates and century month codes are given in the Ethiopian Calendar. The Ethiopian year consists of 365 days, divided into 12 months of 30 days and one month of 5 days (6 days in a leap year). Ethiopia's new year falls on September 11and ends the following September 10 according to the Gregorian calendar. Before the production of any indicators with these data the Ethiopian calendar was converted to the Gregorian calendar but conserving the Ethiopian year; however, the Ethiopian first month is considered in the logic as January, the 2nd as February, etc. For dates including year, month and day the conversion is precise since both calendars have 365 or 366 days; for dates including only year and month, the 13th month was included in December.

Thanks,

Ladys Ortiz
Re: Problem with dates in the Ethiopia datasets [message #13758 is a reply to message #13757] Tue, 19 December 2017 17:03 Go to previous message
kcaglaya@tulane.edu is currently offline  kcaglaya@tulane.edu
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Hi Ladys,

Found it!

I thought you were referring to general Recode Manuals which don't have specific information about this issue. I found the word document for the 2011 survey in the "etir61" folder and it confirms that the reporting of the dates are the same as in 2016.

I would like to thank you, Albert and Bridgette for your help and support.

Happy Holidays.

Regards,

Koray
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