Reparación del daño

Figure 3.2 shows a part of the calendar data form that is used to collect information about contraceptive biographies of individual women (Uganda Bureau of Statistics (UBOS) and ICF International Inc 2012). The calendar data are collected using a table that allows respondents to sequence events over time with the aim of reducing recall error (Callahan and Becker 2012) since respondents are likely to forget reporting all the events as they happened far back in the past. Information is recorded on a month-by-month basis with each cell reflecting the occurrence of an event happening in that month (Ali et al. 2012). In each month, the calendar data reflects the method of contraception used and – if this is not the same method as that used in the previous month – the reason for discontinuation of the previous method.

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Earlier family planning programmes in sub-Saharan Africa targeted married women. Caldwell (1994) observes that unmarried women in East and Southern Africa were actively discouraged from making use of family planning

Interviewers are trained to complete the calendar, and further guides are provided on the questionnaire itself (see Figure 3.2). On the left side of Figure 3.2 are the instructions to aid the interviewer in filling in the form. Each contraceptive method is given a letter code which interviewers enter in the cell for each month.

The calendar also records periods of pregnancy, births as well as terminated pregnancies although there is no distinction made between spontaneous and induced abortion (Ali and Cleland 2010a). On the same side, letter codes are provided to encode for the reasons given by women for discontinuing contraception. On the right side is a graphical representation (depicting months per each year) of at least five years prior to the survey. Interviewers are then required to carefully fill in a letter code (from the key) that matches the contraceptive method used by a woman, or non-use of contraception. Episodes of use and non-use of a method are structured in such a way that method use that results in unexpected pregnancy is categorised as “method failure”; method abandonment after use for some time is categorised as “discontinuation of methods”; and changing of methods from one to another is categorised as “method switching” (Croft et al. 2017).22

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Croft et al. (2017) offer a detailed explanation on completing the questionnaire and the data structure of the contraceptive calendar data conducted in the DHS surveys.

Figure 3.2 Extract from DHS contraceptive use calendar, Uganda 2011

Source: Uganda Bureau of Statistics (UBOS) and ICF International Inc (2012)

3.3.1 Analytic sample for events-based history analysis

The calendar data are stored in a string format. A file in single months was created by de-stringing the calendar data. This transformation creates a data file with person-month observations, where there is one record for every month of use, or non-use of contraception for a single woman. An events file was created with episodes of use, or non-use of contraception. The events file shows a record in the calendar for a specific duration of time. Episodes of use and non-use of

contraception are collected from the start of the calendar up to the interview date. By definition, an episode is a period of uninterrupted use, or non-use of contraception (Ali and Cleland 2010b). However, a woman may have more than one episode of contraceptive use, or non-use of contraception during the period of observation in the calendar.

The DHS standard recode file provides the date for the start of the calendar period.

However, women in the sample have different periods of observation, because of the varying dates of the interview, which makes the analysis of exposure time intricate (Bradley et al. 2009). To standardise the period of observation, all contraceptive biographies of women were maintained for the period between the start of the calendar to the date of the interview. However, in generating a file in single months for analysis, periods of observation were standardised to a period of 60 months prior to the interview date and – following Ali and Cleland (1995) – truncating the data to a point three months before the survey to avoid bias introduced by women not being aware of first trimester pregnancies (Ali and Cleland 1995). Further, the analysis did not consider episodes in progress at the start of the calendar to avoid selection bias, or left censoring (Ali and Cleland 1999), because we do not know when those episodes started.

Thus, based on this standardisation, a summary of the resulting person-months and episodes in the calendar is shown in Table 3.1. The total person-months for each survey represent the total number of events per month for all women for 60 months. The corresponding episodes are the total number of all episodes of events in the person-months file, for a period of 60 months. However, as indicated earlier, the analysis ignored episodes that started before the start of the calendar.

Table 3.1 Person-months and episode files for analyses, five countries, 2011-2015/16 DHSs

Country/ Year of survey Analytic sample Person-months Total Episodes in the data file

Episodes included in the analysis Ethiopia 2011 4,850 291,000 20,139 19,872 Kenya 2014 7,985 479,100 31,326 30,891 Rwanda 2014/15 6,067 364,020 26,488 26,032 Tanzania 2015/16 6,092 365,520 27,436 27,021 Uganda 2011 3,632 217,920 18,222 17,971

Note: Episodes shown in Table 3.1 are for all events in the respective calendars.