Title: Individual and community-level factors associated with early marriage in Zambia: a mixed
effect analysis
Version: 1 Date: 19 Oct 2022
Reviewer:  Jessica L. Schue
Reviewer's report:
Summary
This analysis explores individual and community level factors associated with childhood
marriage across Zambia. The study uses data from three DHS surveys and employs a multilevel
logistical regression approach.
Major Comments
Abstract
• Some of the numerical results do not match the numbers presented in the results section.
Introduction
• First paragraph, sentence starting “The prevalence has consistently been higher…”, provide a
reference and description for the “Girls Not Brides” and the accompanying statistics
• Second paragraph, provide a reference for the sentence: Young girls are also more vulnerable
to sexually transmitted infections (including HIV)
• Third paragraph, sentence starting “However, few studies have explored how the drivers…”
reference number 23 does not match this topic
• Fifth paragraph, sentence starting “In 2018, 31.4% among young women aged 20–24…” the
reference is for a document published in 2017 but the statistic gives 2018 data
Methods
• Why were only complete cases included? The authors should explore if there are any systematic
differences in the types of women who had incomplete data.
• Community level factors section: Clarify how the categories “low, medium, and high” were
defined for each community factor and describe each. For example, what is the definition for
“low community age at first birth”?
• Statistical analysis: Clustering of outcome variable: what clusters are being used, if these are
the sampling clusters from the survey design, clearly state this. This also does not appear in the
results, is it more correct to say “account for the clustering” rather than “examine the clustering”?
• Statistical analysis:  Sentence starting “In order to assess the effects…” Clearly define the
hierarchical levels used in the multilevel models.
• Statistical analysis:  Authors should justify why all covariates were used in the final adjusted
model regardless of the results of the bivariate analyses.
Results
• Sample description section: be sure that if percentages are reported in the table and the text,
that the numbers match, including the number of digits.
• Sample description section, first paragraph: clarify if the proportions given for educational
attainment are those with “only” primary school education or those with “at least” primary school
education.
• Sample description section:   be more precise with the percent of respondents employed, saying
“more than half” can mean 51% or 99%
• Table 1 and Table 2: provide confidence intervals for the estimated percentages
• Table 2: are these the results of the bivariate analyses? If so, clearly indicate that in the table’s
title
• Sample description section:  Third paragraph: what could explain how different the percentage
of reported child marriage are in the two age groups in separate surveys? For example, the 20-24
age group in the 2013 survey should be roughly the same as the 25-29 age group in the 2018
survey, yet the percent reporting child marriage is 49.3 versus 41.0.
• “Factors associated with experience of early marriage” section, second sentence starting with
“results of model IV….” Is long and difficult to follow.
• Table 3: the footnotes describing model III and model IV do not match the data in the table
• “Factors associated with experience of early marriage” section, the results of the multilevel
models could be more fully described, in particular, although nearly all of the covariates in the
model were significant in the univariable models, very few remained significant after adjustment
in the multivariable model.
• “Factors associated with experience of early marriage” section, which model is the “final
model” mentioned in last results paragraph? How was the final model chosen
Discussion
• Second sentence: Verify that the term multivariate is appropriate for this model. Generally,
multivariate refers to the dependent variable having more than 2 outcomes, not having more
than 2 independent variables.
• Second paragraph, last sentence: have any other studies shown an impact from community
level factors?
• Conclusion: what is meant by “marginalized communities”, this is the first time this term has
been used in the paper, it should be defined earlier.
Minor Comments
Abstract
• Results section, sentence starting “Both individual and community….” Grammar error
Introduction
• First paragraph, sentence starting “Child marriage has long been a public health concern”.
Specify what treaties this is referring to.
• Fourth paragraph, sentence starting “There is therefore is a….” spelling and grammar
Methods
• First paragraph, first sentence, add citations for the DHS data used.
• Outcome measures paragraph: it is unclear if the DHS survey asked for an age (i.e. number)
or was just a dichotomous variable for age at first marriage under 18 versus over 18
• Explain the three columns in Figure 1, are each of these from a different DHS year? If so,
label each
• Ensure that all acronyms are defined before their use (i.e. AIC)
• Individual levels paragraph: clarify if partner’s age is age at the time of marriage or age at
the time of the survey
• Community level factors section:  specify which variables are the sociodemographic and which
are the behaviour-related factors.
• Community level factors section:  Is there a difference between community and contextual
level? If not, the language should be streamlined.
Results
• Sample description, fourth paragraph: educational attainment, the last two sentences in this
paragraph are repetitive