Table 4.3 shows the dependent and the independent variable and how they are measured in the data. Most of the variables are measured in nominal or discrete terms and demand qualitative modeling approach for the regression. Antenatal care utilisation which is the dependent variable is measured in two forms to capture the two part model. The first is the frequency of antenatal care visits which is measured in continuous terms; the negative binomial model is used in this respect. The antenatal care is measured in nominal scale to model use and non use of antenatal care through the logit model. Details on how other dependent and independent variables are measured are specified in table 4.3. Also note that wealth index for the 1990 and 1999 NDHS data is not given. The wealth index for these years is generated through the principal component analysis (PCA) to derive the wealth quintile category for each
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group. All the nominal and discrete variables are estimated using dummies with one of the dummies used as a reference category as specified in table 4.3.
The standard errors in the empirical model of all the dependent variables are estimated with robust methods to account for unequal variance. Statistical significance level is considered at 1%, and 5%. The probability value provides the statistical significance of each variable. To find out which variable has the greatest influence, the study tested for interaction terms that are identified to be most significant and most influential. Such variables include; education, region, wealth and religion. The over dispersion parameter β0 in the empirical model is estimated as a constant. The study made use of Stata 12 for all the analysis on the second objective.
Table 4.3 Variables description for objective 2 empirical model Variable Measurement scale Definition
Dependent variables (a) Antenatal care use( logit model)
nominal Antenatal care visits for pregnancy:
women with no ANC visits take the value 0 while women with 1 or more ANC visits takes the value 1.
1 (b) Frequency of antenatal visits (negative binomial model
Continues Antenatal visit for pregnancy: this is measured by number of antenatal visits during pregnancy from 1 to more than one visits
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2 Skilled delivery Discrete/nominal Women who gave birth with the
assistance of Doctor, nurse/midwife and auxiliary midwife takes the value 1, while women that were assisted by TB attendants, relative and friends takes the value 0.
3 immunization Discrete Children who ever had vaccination take the value "1" while those with no vaccination take the value "0".
4 Use of bed nets categorical This is described by "type of bed net child slept under last night". The categories include; 'no bed net", "only treated", "only untreated" .
Independent Variables
1 Age Continuous Current age of respondents. This is measured in years from 15 to 49 in continuous term
3 Region Discrete This is measured in dummies based on
the six geopolitical zones in Nigeria.
North central, North east, North West, South East, South South, South West ( South West is the reference category) 4 Residence Discrete Measured in dummies as "Urban" and
"rural" with rural as a reference category 5 Education/mother's
education
Ordinal/discrete measured in dummies as "No
education", "Primary", "Secondary", "
higher" (higher education is the reference category )
6 Partners
education/father's education
No education, primary, secondary, higher (higher is the reference category)
6 Religion Discrete Measured in dummies as "Christianity",
"Islam", "Traditional" (Christianity is the reference category)
7 Ethnicity Discrete Measured in dummies as
"Hausa/Fulani", "Igbo", "Yoruba", "Tiv",
"Ijaw/Izon", "others" (Hausa is the reference category)
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8 Wealth index Ordinal/discrete Measured in dummies as "Poorest",
"poorer", "middle", "richer", "richest"
(richest is the reference)
9 Wealth Continues Measured by the values of index as
"wealth index factor score".
10 Marital status Discrete Current marital status: Married, single, (married is the reference)
11 Birth order continues Measured by number of children that a woman gave birth to and the order in which they were given birth to. "Birth order number"
12 Distance
To health facility
Getting medical help for self: having to take transport: (a) big problem (b) not a big problem. This is also measured in dummies with "not a big problem" as the reference category.
13 Employment/mother s employment status
Discrete Respondents currently employed : employed, not employed (employed is the reference)
14 insurance Discrete Respondent insured: "insured", "not insured". This is also measured in dummies with "not a big problem" as the reference category.
15 No female provider Discrete Getting medical help for self: concern no female provider: (a) big problem (b) not a big problem. This is also measured in dummies with "not a big problem" as the reference category.
16 No provider Discrete Getting medical help for self: concern no provider: (a) big problem (b) not a big problem. This is also measured in dummies with "not a big problem" as the reference category.
17 No immunisation drugs
Discrete Getting medical help for self: concern no drugs: (a) big problem (b) not a big problem (not a big problem is the reference). This is also measured in dummies with "not a big problem" as the
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reference category.