2009 Australian and New Zealand Stata Users Group meeting: Abstracts
Thursday, November 5, 2009
The impact of water supply and sanitation interventions on child health: Evidence from Demographic and Health Surveys
Ron Bose, rbose@3ieimpact.org
International Initiative for Impact Evaluation (3ie)
In this presentation, I examine the impacts on child health, using diarrhea as the
health outcome, (among children living in households) with access to
different types of water and sanitation facilities, and from socioeconomic
and child specific factors. Using multiyear cross-sectional health DHS
data, I employ the quasi-experimental estimators (matching) to match
children belonging to different treatment groups, defined by water types and
sanitation facilities, with children in a control group. Quantile
regression models are used to benchmark results and to check for their
robustness. The empirical framework yields strong support that access to
improved sanitation has had a substantial impact on reducing the (predicted)
diarrhea outcomes. This is especially true among very young children defined
as those below 24 months of age whose rates of diarrhea have shown the largest
declines between 2001 and 2006. These estimates serve as an input into
cost-effectiveness analysis that compares the provision of increased access
to sanitation with other public health interventions in developing nations
(especially sub-Saharan Africa and South Asia) to underline its importance
in achieving Millennium Development Goals (MDGs).
Effects of lack of independence in meta-epidemiology
Peter Herbison, peter.herbison@otago.ac.nz
University of Otago
Meta-epidemiology is the use of the characteristics of individual reports of
randomized trials to examine the effects on meta-analyses. Traditionally
only one meta-analysis from a systematic review is included in these
studies, due to a fear of what would happen because of the lack of
independence if the same study was included in more than one meta-analysis.
We have some data on 64 meta-analyses but these come from only 18 systematic
reviews. Papers submitted from this data have been heavily criticized
because of the feared effects of this lack of independence. One suggestion
for a sensitivity analysis is to randomly select one meta-analysis from each
systematic review. As an extension to that I chose to bootstrap the results
of interest to examine the effects of the lack of independence. Stata makes
these analyses trivial. This talk will present the results of two such
sensitivity analyses and show that the lack of independence appears to have
little effect on the interpretation of the results.
Meta-analysis in animal health and reproduction: Methods and applications using Stata
I.J. Lean, ianl@dairydocs.com.au
A.R. Rabiee, ahmadr@dairydocs.com.au
SBScibus
Meta-analysis is a rapidly expanding area of research that has been
relatively underutilized in animal and veterinary science. It is a
quantitative, formal, epidemiological study design used to systematically
assess previous research studies to derive conclusions about that
body of research. Outcomes from a meta-analysis may include a more precise
estimate of the effect of treatment or risk factor for disease, or other
outcomes, than any individual study contributing to the pooled analysis.
The examination of variability or heterogeneity in study results is also a
critical outcome. Examples where meta-analyses have been repeated in animal
science or veterinary medicine show good consistency in estimates of effect.
Rigorously conducted meta- analyses are useful tools to improve animal
well-being and productivity. The need to integrate findings from many
studies ensures that meta-analytic research is desirable and the large body
of research now generated makes the conduct of this research feasible.
Many of the statistical methods to conduct meta-analysis are widely used. In
this presentation, we will demonstrate how Stata can provide a comprehensive
suite of programs that can be used in meta-analysis. Some detail on the
common statistical methods used, such as metan and metareg, is
presented and examples of when these have been used in studies using cattle
are provided. The post-hoc methods used to evaluate heterogeneity and
publication bias (metabias, confunnel>), which include the I2
statistic, L’Abb plots, Galbraith plots, Rosenthal’s N, and
influential study analysis are exclusively used in meta-analysis.
Formatted output tables in a flexible way
Markus Hahn, mhahn@unimelb.edu.au
Melbourne Institute of Applied Economic and Social Research
itab.ado is a new command that provides a framework to users, which
allows them to create formatted output tables in a flexible way. Tables can
be created in an interactive manner by using the command line or by using
do-files or ado-files. Each table can be fitted with the appropriate
formatting so that it can be included into the final document straightaway.
No matter which of the supported output formats is used, the command applies
the same look and feel to any given table and as such provides a so lution
to generate the same table for different output formats. The supported
output formats are Excel, LaTeX, HTML, Comma-Separated Value (CSV) files, and
SMCL. The command works well with other user written commands such
as the popular outreg, outreg2, estout, and
tabout commands. The output of these commands can be extended or
modified, for example, by adding more information or by applying a different
formatting.
Automating reports with Mata and mail merge
Karl Keesman, sales@survey-design.com.au
Survey Design and Analysis
Mail merge is a convenient way of getting data into a report. It allows data
to be interspersed between normal report texts. Graphs and table data can
also be input with mail merge.
Where standard reports are required on a regular basis or large numbers of
reports are required, automating the reporting process saves time and
reduces the chance of errors.
Stata and Mata can generate an output that mail merge can read. This will be
demonstrated using a simple example. The commands and process of doing this
with Mata will be explained.
Complementing Stata with geovisualization
Philip S. Morrison, philipmor@gmail.com
Victoria University of Wellington—New Zealand
Statistical agencies are increasingly recognizing the value of configuring
their data in formats that facilitate geovisualization—the representation
of data across the geographic domain. For Stata users this poses a challenge
because the present geovisualization capacity within the conventional
Stata product is quite limited.
This presentation reports on a project completed for Statistics New Zealand
on Geovisualization where graphical tools from Stata were complemented by
the geovisualization capacity afforded by GeoViz. The presentation
illustrates the returns to geovisualization via a specific case study and
considers the advantages that could potentially accrue to Stata users if
such a capacity was provided within the Stata system itself.
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