Fifth Stata-User-Meeting in Essen
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The 5th German Stata Users Group Meeting will be held on Monday, 2nd April
2007 in Essen at the RWI (Rheinisch-Westf=C3=A4lisches Institut f=C3=BCr
Wirtschaftsforschung). We would like to invite everybody from everywhere wh=
o
is interested in using Stata to attend this meeting.
The academic program of the meeting is being organized by Johannes Giesecke=
,
University of Mannheim (<[email protected]>), John P.
Haisken-DeNew, RWI Essen (<[email protected]>), and Ulrich Kohler,
WZB (<[email protected]>). The conference language will be English due to the
international nature of the meeting and the participation of non-German gue=
st
speakers.
The logistics of the conference are being organized by Dittrich und Partner=
,
distributor of Stata in several countries including Germany, The Netherland=
s,
Austria, and Poland (http://www.dpc.de).
Program Schedule
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
8:30 - 9:00 Reception
9:00 - 9:10 Welcome
John P. HaiskenDeNew, RWI Essen
Key Notes
---------
9:10 - 9:50 Why should you become a Stata programmer?
Kit Baum <[email protected]>, Boston College Economics
9:50 - 10:30 Making regression tables simplified
Ben Jann <[email protected]>, ETH Zurich
Abstract
-estout-, introduced by Jann (2005), is a useful tool for producing regress=
ion
tables from stored estimates. However, its syntax is relatively complex and
commands may turn out lengthy even for simple tables. Furthermore, having t=
o
store the estimates beforehand can be a bit cumbersome. To facilitate the
production of regression tables, I therefore present two new commands calle=
d
-esto- and -esta-. -esto- is a wrapper for official Stata's -estimates stor=
e-
and simplifies the storing of estimation results for tabulation. For exampl=
e,
-esto- does not require the user to provide names for the stored estimation
sets. -esta-, on the other hand, is a wrapper for -estout- and simplifies
compiling nice-looking tables from the stored estimates without much typing=
=2E
Basic applications of the commands and usage of -esta- with external softwa=
re
such as LaTeX, Word, or Excel will be illustrated by a range of examples.
10:30 - 10:45 Coffee
General Statistics
------------------
10:45 - 11:15 Assessing the reasonableness of an imputation model
Maarten L. Buis <[email protected]>, Vrije Universiteit Amsterdam
Abstract
Multiple imputation is a popular way of dealing with missing values under t=
he
Missing At Random (MAR) assumption. Imputation models can become quite
complicated, for instance when the model of substantive interest contains
many interactions, or when the data originate from a nested design. This
paper will discuss two methods to assess how plausible the results are. The
first method consists of comparing the point estimates obtained by multiple
imputation with point estimates obtained by another method for controlling
for bias due to missing data. Second the changes in standard error between
the model that ignores the missing cases and the multiple imputation model
are decomposed into three components: changes due to changes in 'sample
size', changes due to uncertainty in the imputation model used in multiple
imputation, and changes due to changes in the estimates that underlie the
standard error. This decomposition helps in assessing the reasonableness of
the change in standard error. These two methods will be illustrated with tw=
o
new user written Stata commands.
11:15 - 11:45 The influence of categorizing survival time on parameter
estimates in a Cox model
Anika Buchholz, Willi Sauerbrei, Patrick Royston
University of Freiburg, University Medical Center Freiburg, MRC Clinical
Trials Unit, London
Abstract
With longer follow-up times the proportional hazards assumption is
questionable in the Cox model. Cox suggested to include an interaction
between a covariate and a function of time. To estimate such a function in
Stata a substantial enlargement of the data is required. This may cause
severe computational problems. We will consider categorizing survival time,
which raises issues as to the number of cutpoints, their position, the
increased number of ties and the loss of information, to handle this proble=
m.
Sauerbrei et al. (2007) proposed a new selection procedure to model potenti=
al
time-=C2=ADvarying effects. They investigate a large data set (N=3D2982) wi=
th 20
years follow-=C2=ADup, for which the Stata command stsplit creates about 2.=
2
million records. Categorizing the data in 6 month intervals gives 35747
records. We will systematically investigate the influence of the length of
categorization intervals and the four methods of handling ties in Stata. Th=
e
results of our categorization approach are promising, showing a sensible wa=
y
to handle time-varying effects even in simulation studies.
References: Sauerbrei, W., Royston, P. and Look, M. (2007). A new proposal =
for
multivariable modelling of time-=C2=ADvarying effects in survival data base=
d on
fractional polynomial time-transformation. Biometrical Journal, in press
11:45 - 12:15 Oaxaca/Blinder Decompositions for Non-Linear Models
Matthias Sinning <[email protected]> and Markus Hahn <[email protected]>=
,
RWI Essen, University of Bochum
Abstract
This paper describes the estimation of a general Blinder-Oaxaca decompositi=
on
of the mean outcome differential of linear and non-linear regression models=
=2E
Departing from this general model, it is shown how it can be applied to
different models with discrete and limited dependent variables.
12:15 - 13:15 Lunch
13:15 - 13:45 Estimating Double-Hurdle Models with Dependent Errors and
Heteroscedasticity"
Julian A. Fennema <[email protected]>, Heriot-Watt University, Edinburgh
Abstract
This paper describes the estimation of the parameters of a double hurdle mo=
del
in Stata. It is shown that the independent double-hurdle model can be
estimated using a combination of existing commands. Likelihood evaluators t=
o
be used with Stata's ml facilities are derived to illustrate how to fit
independent and dependent inverse hyperbolic sine double-hurdle models with
heteroscedasticity."
Distributions
-------------
13:45 - 14:15 Measuring Richness
Andreas Peichl <[email protected]> University of Cologne
Abstract
In this paper, we describe richness, a Stata program for the calculation of
richness indices. Peichl, Schaefer and Scheicher (2006) propose a new class
of richness measures to contribute to the debate how to deal with the
financing problems that European welfare states face as a result of global
economic competition. In contrast to the often used headcount, these new
measures are sensitive to changes in rich persons=E2=80=99 income. This all=
ows for a
more sophisticated analysis of richness, namely the question whether the ga=
p
between rich and poor is widening. We propose to use our new measures in
addition to the headcount index for a more comprehensive analysis of
richness.
14:15 - 14:45 Robust income distribution analysis
Philippe Van Kerm <[email protected]>, CEPS/INSTEAD, Luxembourg
Abstract
Extreme data are known to be highly influential when measuring income
inequality from micro-data. Similarly, Lorenz curves and dominance criteria
are very sensitive to data contamination in the tails of the distribution. =
In
this presentation, I intend to introduce a set of user-written packages tha=
t
implement robust statistical methods for income distribution analysis. Thes=
e
methods are based on the estimation of parametric models (Pareto,
Singh-Maddala) using "optimal B-robust" estimators rather than maximum
likelihood. Empirical examples show how robust inequality estimates and
dominance checks can be derived from these models.
14:45 - 15:00 Coffee
Data Management
---------------
15:00 - 15:25 PanelWhiz: A Stata Interface for Large Scale Panel Data Sets
John P. Haisken-DeNew <[email protected]>, RWI Essen
Abstract
This paper outlines a panel data retrieval program written for Stata/SE or
better, which allows easier accessing of the household panel data sets. Usi=
ng
a drop-down menu system, the researcher selects variables from any and all
available years of the panel. The data is automatically retrieved and merge=
d
to form a "long file", which can be directly used by the Stata panel
estimators. The system implements modular data cleaning programs called
"plugins". Yearly updates to the data retrievals can be made automatically.
Projects can be stored in libraries allowing modular administration and
appending. PanelWhiz is available for SOEP, IAB-Betriebspanel, HILDA,
CPS-NBER, CPS-CEPR. Other popular data sets will be supported soon.
15:25 - 15:50 PanelWhiz Plugins: Automatic Vector-Oriented Data Cleaning fo=
r
Large Scale Panel Data Sets
Markus Hahn <[email protected]>, RWI Essen and University of Bochum
Abstract
PanelWhiz "plugins" are modular data cleaning programs for specific items i=
n
PanelWhiz. Each plugin is designed to recode, deflate, change existing
variables being extracted in a panel-data retrieval. Furthermore new
variables can be generated on the fly. The PanelWhiz plugin system is a
"macro language" that uses new-style dialog boxes and Stata's modularized
"class" system, allowing a vector orientation for data cleaning. The
PanelWhiz plugins can even be generated using a PanelWhiz plugin front-end,
allowing users to create plugins but not have to write Stata code themselve=
s.
The system is set up to allow data cleaning of ANY PanelWhiz supported data
set.
15:50 - 16:15 A model for transferring variables between different data-set=
s
based on imputation of individual scores
Bojan Todosijevic <[email protected]>, University of Twente
Abstract
It is an often encountered problem that variables of interest are scattered=
in
different data sets. Given the two methodologically similar surveys, a
question not asked in one survey could be seen as a special case of missing
data problem (Gelman et al., 1998). The paper presents a model for
transferring variables between different data-sets applying the procedures
for multiple imputation of missing values. The feasibility of this approach
was assessed using two Dutch surveys: Social and Cultural Developments in T=
he
Netherlands (SOCON 2000) and the Dutch Election Study (NKO 2002). An
imputation model for the left-right ideological self-placement was develope=
d
based on the SOCON survey. In the next step, left-right scores were imputed
to the respondents from the NKO study. The outcome of the imputation was
evaluated, first, by comparing the imputed variables with the left-right
scores collected in three waves of the NKO study. Second, the imputed and t=
he
original NKO left-right variables are compared in terms of their associatio=
ns
with a broad set of attitudinal variables from the NKO data set. The result=
s
show that one would reach similar conclusions using the original or imputed
variable, albeit with the increased risk of making Type II errors.
16:15 - 16:30 Coffee
16:30 - 17:00 Two Issues on Remote data access
Peter Jacobebbinghaus <[email protected]>, IAB
Abstract
At the Research Data Centre of the BA at the IAB, researchers can send in
Stata programs to be processed there with the log files sent back to them
after a disclosure limitation review. This method of data access is called
remote data access and the reason we do this is data confidentiality. Remot=
e
data access has two non-standard requirements: Efficient use of the compute=
r
resources and automation of parts of the disclosure limitation review. I
would like to talk about how we deal with these requirements and discuss wa=
ys
to improve them.
17:00 - 17:30 Report to the Users
Bill Rising, StataCorp
17:30 - 18:00 Wishes and Crumbles
18:00 End of the meeting
Participants are asked to travel at their own expense. There will be a smal=
l
conference fee to cover costs for coffee, teas, and luncheons (25 Euro;
Students: 10 Euro). There will also be an optional informal meal at a
restaurant in Essen on Monday evening at additional cost (20 Euro).
You can enroll by contacting Anke Mrosek by email or by writing, phoning, o=
r
faxing to
Anke Mrosek
Dittrich & Partner Consulting GmbH
Kieler Str. 17
42697 Solingen
Tel: +49 (0) 212 260 66-24
Fax:+49 (0) 212 260 66 -66
[email protected].
We look forward to seeing you in Essen on April 2nd where you can help us t=
o
make this an exciting and interesting event.
The conference venue is:
RWI Essen
Hohenzollernstr. 1-3
45128 Essen
(see http://www.rwi-essen.de)
Johannes Giesecke, John P. Haisken-DeNew, Ulrich Kohler
--=20
Ulrich Kohler
[email protected]
030/25491-361
--=20
Ulrich Kohler
[email protected]
030/25491-361
*
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