multiple unordered categorical dependent variables in organizational research
TRANSCRIPT
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Running head: DEPENDENT CATEGORICAL VARIABLES
Multiple Unordered Categorical Dependent Variables in Organizational Research
Peter Westfall*
Rawls College of Business Administration Texas Tech University Lubbock, TX 79409 Tel: (806) 742-2174 Fax: (806) 742-3191 [email protected]
James J. Hoffman
Rawls College of Business Administration Texas Tech University Lubbock, TX 79409 Tel: (806) 742-4004 Fax: (806) 742-3191 [email protected]
Jun Xia
Rawls College of Business Administration Texas Tech University Lubbock, TX 79409 Tel: (806) 742-1534 Fax: (806) 742-2308
[email protected] Topic areas: 4a, 6.m.v. (Multivariate Categorical Response Variables), and 6.r. * Corresponding Author
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Multiple Unordered Categorical Dependent Variables in Organizational Research
Abstract
A model for analyzing multiple categorical dependent variables is presented and
developed for use in organizational research. A primary example occurs in the foreign market
entry literature, where choice of ownership (majority, equal, or minority) and “function”
(acquisition or joint venture) are simultaneously endogenous; only separate univariate
ownership-based and function-based choice models are considered in the literature. Another
example is in the comparison of gender and race across organizational units, controlling for
confounders such as experience and qualification. Subsuming univariate categorical dependent
variables as a special case, the model unifies existing organizational research methods, mitigates
bias associated with univariate methods, provides more powerful testing methods, and provides a
flexible modeling framework that allows hypotheses to be modeled and tested that are not
possible with univariate models. Standard software may be used for estimation and testing;
examples are given.
Key words: Conditional Logit, Entry Mode, Gender Discrimination, Multinomial Logit, Odds
Ratio.
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Joint Analysis of Multiple Categorical Dependent Variables in Organizational Research
Categorical measures abound in organizational research. In cases where such measures
are predictor variables, they are often used as control variables or moderator variables. For
example, ethnicity and gender might moderate the effect of test scores on performance.
Regression and structural equations methods are reasonably well developed for such applications;
see Aguinis, Boik, and Pierce (2001), and Williams, Edwards, and Vandenberg (2003), for
examples.
Applications where categorical measures are dependent variables also are common. For
example, in the market entry literature, the categorical measure “function” (acquisition or joint
venture) has been predicted in terms of cultural variables and control variables (e.g., Kogut &
Singh, 1988; Anand & Delios, 1997; Folta & Ferrier, 2000); other researchers have considered
the categorical measure “ownership” (equal, minority, majority) using similar models (e.g.,
Hennart, & Larimo, 1998; Pan, 1996; Erramilli, 1996). For another example, when comparing
ethnic hire percentages across organizations and/or divisions, controlling for exogenous effects,
the variable “ethnicity” is a categorical dependent variable (Holzer, 1998; Shaw, 2004; Giuliano,
Levine, & Leonard; 2005). Yet another example is firm survival, which has been treated as a
binary dependent variable that can be predicted by the level of education of business owners (e.g.,
Chen and Astebro, 2003).
Models for predicting univariate categorical outcomes are commonplace; methods
include logistic and probit regression for binary and ordinal categorical response, and
multinomial logistic regression and the conditional logit model for unordered categorical
response. However, organizational research often requires multivariate dependent measures.
When such measurements are in the metric (numeric) scale, a plethora of methodologies are
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available, including structural equations models, path analysis, partial least squares, multivariate
analysis of variance or covariance, or moderated multiple regression.
On the other hand, few methods are readily available to the organizational researcher for
the case where there are multiple non-metric (categorical) dependent measures. For multiple
ordered categorical responses, one may use multivariate probit models (Zajac & Westphal, 1996;
Keister, 2004). However, in addition to the assumption of ordered responses, these models
require additional restrictive assumptions in the case of higher dimensional responses to allow
computational tractability (Bock & Gibbons, 1996). Thus, while the available methodologies for
ordered categorical response variables are limited, there seems to be no method whatsoever that
is in general use for multivariate unordered categorical variables in organizational research, a gap
we aim to fill.
Thus, the goal of this paper is to popularize a class of models for the analysis of multiple
unordered categorical response variables. These models are estimated via special application of
the conditional logit model, and therefore may be analyzed easily using existing software,
although the researcher must create various dummy variables and interaction terms. We do not
claim that the model is new, only that it is under-utilized. Original references include Nerlove
and Press (1973), Amemiya (1981), Lehrer and Stokes (1985), and Stokes (1997).
In order to introduce the reader to the fundamentals of the model and illustrate how the
model may be used for the analysis of multiple unordered categorical response variables we
develop theory, extensions, and software implementations for this model using two different
examples that are of interest to organizational researchers. In the first example we consider a
hypothetical case of assessing race and gender bias of hiring practices of managers. In the
second example we conduct an empirical analysis dealing with predicting function and
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ownership in international entries. The paper then concludes with a discussion of the benefits of
using the model for multiple categorical responses (as opposed to separate univariate analyses).
It should be noted that since it is always possible to transform a metric measure (e.g.,
income) to a categorical measure via segmentation, the model we consider applies equally to
metric measures where categorization is used; this is true for both univariate and multivariate
models. Such segmentation is often done when the response measure is badly skewed (like the
distribution of income), or simply when the categories make sense. Thus, we consider only
models for unordered categorical responses, which are appropriate even when the categories are
ordered, if the effects of predictors on the response are non-linear.
Example One: A Hypothetical Case of Assessing Race and Gender Bias of Hiring Practices of Managers
To illustrate the need for handling multiple categorical responses jointly rather than
separately, via univariate models, consider a hypothetical case of assessing race and gender bias
of hiring practices of managers. This may be done by comparing the (race/gender) distribution
of hires for managers of class A versus the same distribution for managers of class B. Class A
and B might be minority and nonminority, or Male and Female, or of certain personality
characteristics (such as a “Type A” personality); it doesn’t matter for the purposes of this
illustration. In this application, both race and gender are acknowledged by the manager at the
time of the hiring choice, and if there is bias, there may well be an interaction between the two
variables (e.g., “double counting” for female minorities). Meanwhile, manager type (A or B) is a
pre-existing condition. Thus, gender and race are jointly endogenous, and manager type is
exogenous.
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Table 1 below shows an example where gender-based and race-based univariate models
each would be misleading. Entries within the table are hypothetical counts of hires, cross-
classified by race, gender and manager group.
Table 1. Hypothetical case where manager type affects interaction between race and gender Managers of type A Managers of type B Race\Gender Female Male Total Female Male Total Minority 30 70 100 70 30 100 Non-Minority 70 30 100 30 70 100 Total 100 100 200 100 100 200
In this hypothetical example, manager type has strong effects on gender hire and on race
hire within categories of the other variable. However, if the data are pooled across one or the
other variables, as is done using the (univariate) binary logit models, then only data in the “total”
entries specific to that variable are used. Table 2 compares univariate analyses with those of the
multivariate model (bivariate in this example) that we promote.
Table 2: Results of univariate categorical response model and bivariate categorical response model analysis of data in Table 1.
Model 1 Model 2 Model 3 Prediction of Gender Prediction of Race Prediction of Gender/Race
Dependent Measure Contrast β̂ s.e. β̂ s.e. β̂ s.e.
Gender Main Effect Female/Male 0.000 0.200 -- -- 1.695 0.309 Race Main Effect Minority/NonMinority -- -- 0.000 0.200 1.695 0.309 Gender*Race Interaction (Minority/Nonminority)
/(Female/Male) -- -- -- -- -3.389 0.436
Estrella (1998) R2 0.000 0.000 0.156
As seen, manager type appears to have absolutely no effect whatsoever on race or gender,
no matter which of the two univariate response variables were selected for the analysis. On the
other hand, the bivariate model assesses effects of predictors upon each response variable
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individually, as well as upon their interaction, showing strong, significant effects. Thus the
bivariate model is more appropriate.
One might argue in the case shown in Table 1 that separate analyses should be performed
within categories of the other variable; in other words, that effects of manager type upon gender
should be studied separately for minorities and nonminorities, and vice versa. However, there
are two problems with this approach: first, it leads to four models, with no formal mechanism to
combine information across them. Second, conditioning upon either race or gender in this
fashion implies that race or gender is exogenous, contrary to the theory that they are jointly
endogenous. In contrast, the bivariate model contains the same information that is contained in
the separate models, and treats the responses as jointly endogenous.
Another approach would be to treat the choice of race/gender mode as a four-level
multinomial response. This solves the problems noted above, and is similar to the bivariate
model. However, the bivariate model subsumes the univariate models as special cases:
parameter estimates and standard errors from univariate models are obtained exactly by
specifying only the “main effects” associated with the univariate choice variable in the bivariate
model. The bivariate model also allows simple determinations of effects of exogenous predictors
on the interaction between endogenous choices, which, though possible with the multinomial
logit model, is much more cumbersome. Finally, the bivariate model provides a more flexible
modeling procedure in which higher order interactions can be tested and included only as needed
based on standard measures of model fit, such as AIC and SBC; the bivariate model is thus the
more natural and useful formulation.
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Development of the Model
Utility Theory Formulation
The model is motivated by utility theory that gives rise to the conditional logit model
(CLM). The CLM is ordinarily expressed as a univariate model, but is easily extended to the
multivariate case. The standard CLM is motivated by the utility model
Uj = Xj’β + εj, (1)
where Uj is the utility of selecting choice j, Xj is a vector of exogenous predictors that may
depend on choice j, and where εj, j=1,…,J, are independent and identically distributed random
variables having the distribution exp{-exp(-εj)}, also known as the Type I extreme value, or
Gumbel, distribution. When the utility Uj of choice j is highest among (U1,…,UJ), choice j is
selected. Under these assumptions, the choice selection probabilities are given by
P(Choice j is selected) = exp(Xj’β)/ Jk 1=Σ exp(Xk’β), (2)
called the conditional logit model (CLM) by McFadden (1974). While the utility formulation (1)
mathematically justifies the CLM, it is not necessary to posit existence of utilities to use (2).
However, when using (2) without assumption (1), one still must assume independence from
irrelevant alternatives (see e.g., Talluri & van Ryzin, 2004).
Software is readily available to estimate (2); for example, the SAS/ETS procedure PROC
MDC estimates them directly, and the SAS/STAT procedure PROC PHREG can estimate them
as well (Allison, 1999). In STATA, one can use the MCL module.
Extending model (1) and (2) to multivariate response variables is conceptually simple: if
there are two responses with I and J possible choices, respectively, then the choice subscript j in
models (1) and (2) refers to a particular combination of the two response choices, and J in
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models (1) and (2) is replaced with IJ, the total number of combined choices. For an exogenous
predictor variable X, such a model is generically defined as
Utility =
(baseline main effect on choice variable 1) + (baseline main effect on choice variable 2) +
(baseline effect on interaction between choice variables 1 and 2) +
(effect of X on choice variable 1) + (effect of X on choice variable 2) +
(effect of X on interaction between choice variables 1 and 2) + ε. (3)
To implement model (3) using statistical software, let d(1)i, i=1,…,I-1, denote dummy
variables for choice variable 1, and let d(2)j, j=1,…,J-1, denote dummy variables for choice
variable 2. The model is then estimated as
Utility = (α(1)1 d(1)1 + …+ α(1)I-1 d(1)I-1) + (α(2)1 d(2)1 + …+ α(2)J-1 d(2)J-1) +
(α(12)1,1 d(1)1d(2)1 + …+ α(12)I-1,J-1 d(1)I-1d(2)J-1) +
(β(1)1 d(1)1X + …+ β(1)I-1 d(1)I-1X) + (β(2)1 d(2)1X + …+ β(2)J-1 d(2)J-1X) +
(β(12)1,1 d(1)1d(2)1X + …+ β(12)I-1,J-1 d(1)I-1d(2)J-1X) + ε. (4)
Model (4) accounts for the fact that model (2) is over-parameterized by excluding one in
the list of possible dummy variables.
Extension of (4) to three or more choice variables is simple: in the case of three choice
variables there will be three sets of interaction terms involving two of the variables, and one set
of terms involving all three; these correspond to two-way and three-way interactions in an
analysis of variance (ANOVA). Extensions to four and higher follows the same pattern.
Extension to multiple exogenous predictors is also simple; one simply includes all product terms
involving the additional predictors, using the same form as shown in (4).
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With more dependent and predictor variables, the complexity of the model grows quickly,
and sparse data in combination cells can render models with higher-level interaction terms non-
identifiable. Thus it is usually important not to include all terms. Parsimonious model selection
is readily accomplished by evaluating interaction terms in (4) via likelihood ratio tests, AIC, or
BIC as desired, and by removing unneeded interactions (backwards deletion), or including
needed terms (forward selection).
Software Implementation
Consider model (4) in the context of the analysis in Table 2. Choice variable 1 is
“Gender” and Choice variable 2 is “Race”, and the variables in (4) are defined as
d(1)1 = 1 if Race is “Minority”; d(1)1 = 0 otherwise
d(2)1 = 1 if Gender is “Female”; d(2)1 = 0 otherwise
X = 1 if manager is Type A; X = 0 otherwise.
To estimate the bivariate model shown in Table 2 using PROC MDC of SAS/ETS, the syntax is
model choice = dMin dFem dMin_dFem
dMin_TypeA dFem_TypeA dMin_dFem_TypeA/type = clogit nchoice = 4;
where the “d” prefix denotes the appropriate dummy variables, the underscores “_” indicate
product, and the remaining terms are products as indicated in model (4). Here, the “TypeA”
term is a binary indicator, but in general it can be any numerical measure. The data structure for
both PROCs PHREG and MDC of SAS requires that the data contain as many rows as choices
per observational unit; i.e., if there are 1000 observations, and each observation corresponds to a
single choice from a set of four choices, then the input data set will have 4000 rows. All SAS
code is freely available from the first author.
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To estimate the univariate models in Table 2, exclude all of the variables associated with
one or the other choice variable, e.g., for minority only,
model choice = dMin dMin_TypeA/type = clogit nchoice = 4;
In general models there will be more terms to include: I-1 baseline dummy variables for
variable 1, J-1 for variable 2, and (I-1)(J-1) for interactions, giving IJ-1 baseline dummies. There
are product terms involving X as well for all of these terms, giving an additional IJ-1 terms with
one X, and in general k(IJ-1) possible additional terms for k predictor variables. This increase in
complexity underscores the need for parsimony. Generally, not all possible terms should be
included, especially when data are sparse for some combinations of response variable choices.
Simpler models should be specified a priori in confirmatory analyses, and variable selection
should be performed in exploratory analyses.
Parameter Interpretation
Again considering the example of Table 2, let
Oij(X) = P((i,j) selected | X)/ P((2,2) selected | X)
denote the odds favoring choice (race i, gender j) to the (NonMinority, Male) choice (the
(NonMinority, Male) choice is the left-out combination category in the dummy variable
definitions given above). The conditional logit model (2) implies that the log odds ratios
ln{Oij(X=1)/Oij(X=0)} are as given in Table 3.
Table 3. Log odds ratios showing the effect of manager type Female Male Minority β(1)1 + β(2)1 + β(12)1,1 β(1)1 Nonminority β(2)1 0
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Interpretations are simplest in the model when there is no interaction; i.e., when β(12)1,1 =
0. In this case β(1)1 is the effect of manager type on minority choice, in either gender category.
Specifically, the log odds ratio of Minority selection is β(1)1 higher than the log odds ratio of
Nonminority, in either level of gender. Similarly, when there is no interaction, β(2)1 is the effect
of manager type on gender choice, for either race category. Specifically, the log odds ratio of
Female selection β(2)1 higher than the log odds ratio of male selection, in either race category.
In the interaction model, it is not as easy to interpret the parameters, and often graphical
methods are used (e.g., Cannella & Shen, 2001) to display interaction effects clearly.
Nevertheless, all parameters remain interpretable as log odds ratios in the case where β(12)1,1 ≠ 0,
via inspection of Table 3. In this case β(1)1 is the effect of manager type on minority hires in the
male category only. Similarly, when there is no interaction, β(2)1 is the effect of manager type on
female hires, in the Nonminority category only. Finally, the interaction term β(12)1,1 is the effect
of manager type on the (2x2) interaction between race and gender selection. Specifically, the
difference between log odds ratios of Female and Male selections among Minority hires is β(12)1,1
higher than the difference between log odds ratios of Female and Male selections among
Nonminority hires.
Thus, in table 2, we have the following interpretations:
• (1)1 β = 1.695 is the estimated effect of manager type on minority selection in the male
category.
• (2)1 β = 1.695 is the estimated effect of manager type on female selection in the Nonminority
category.
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• (12)1,1 β = -3.389 is the estimated effect of manager type on the
(Minority/Nonminority)/(Female/Male) interaction between choices.
Note that when there are more than two categories, the same interpretations are used, but
one must keep in mind that effects are on differences from the excluded categories used in the
dummy variable formulations. Note also that the interpretations are identical when there are
additional predictor variables, with the usual “ceteris paribus” caveat concerning the additional
variables. Finally, note that the predictors are more often continuous rather than binary, in which
case the “effect” of a predictor is interpreted as the effect of a one unit increase in the predictor.
Estimation, Inference and Model Fit
All parameters may be estimated via standard maximum likelihood procedures;
inferences are available using standard large-sample likelihood-based procedures (Greve &
Taylor, 2000; Cannella & Shen, 2001; Gibson & Zellmer-Bruhn, 2001). Alternatively, Bayesian
methods may be used (O’Brien & Dunson, 2004); Bayesian methods solve difficulties with
maximum likelihood that are caused by sparse data, non-identifiability, and non-convergence,
but obtaining software may be more difficult for Bayesian methods than for likelihood methods.
When comparing different models, such as the interaction models versus no-interaction models,
we suggest using likelihood ratio tests; when reporting results of estimated models, we suggest
using Wald standard errors of the parameters (e.g., Agresti, 2002: 11). Predictive ability can be
assessed using maximized log-likelihood values, generalized R2 statistics (Estrella, 1998,
provides an overview), and AIC statistics to guard against over-parameterization (e.g., Bozdogan,
1987).
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Predicting Function and Ownership in International Entries
The multivariate dependent categorical variable model we consider was motivated by the
literature on predicting foreign market entry modes using cultural characteristics. A problem in
this stream of organizational research is that the models that have been used are univariate; some
predicting function (acquisition or joint venture; see Kogut & Singh, 1988; Anand & Delios,
1997; Folta & Ferrier, 2000), and some predicting ownership (minority, equal, or majority; see
Hennart, & Larimo, 1998; Pan, 1996; Erramilli, 1996). However, theory suggests that the
responses are jointly endogenous (multivariate), rather than univariate: firms entering
partnerships will determine the function and choice parameters of the agreement simultaneously,
and interactively. For example, a less desirable ownership level may be acceptable given a
desirable function. Hence, the variables function and ownership are jointly endogenous. Clearly
exogenous variables are the economic, political and social conditions, cultural and firm-specific
characteristics. The bivariate model avoids potential biases due to pooling effects as illustrated
in Tables 1 and 2, and also allows researchers to address questions such as, “do cultural variables
affect function or ownership most strongly?” and “do cultural variables affect the interaction
between function and ownership?”
As noted by Shenkar (2001), the foreign entry literature lacks a comprehensive
framework to fully understand the theoretical and empirical issues surrounding the influences of
national culture on foreign entry mode selections. The bivariate choice model predicts function
and ownership simultaneously, and subsumes the univariate models as special cases. Thus, the
bivariate model provides a comprehensive framework as advocated by Shenkar, and can resolve
at least some of the theoretical and empirical issues in this stream of organizational research.
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To illustrate the method, we obtained data on 2085 completed international entries where
one of the partners was a Chinese firm, and another was a foreign manufacturing firm. All data
were selected from the Securities Data Company (SDC) Platinum database, and only entries with
complete information on the variables we considered were selected (see Hennart, 1991; Hennart
& Larimo, 1998; Makino & Neupert, 2000 for similar studies).
The response variables are MODE, the function-based entry mode selection (joint venture
or acquisition), and OWNSHIP, the foreign ownership level selection (majority, >50%
ownership; equal, 50% ownership; or minority, <50% ownership). Most entries are firms from
the United States, Japan, Hong Kong, Germany, France, the United Kingdoms, and Singapore;
the raw counts are given in Table 4.
Table 4. Combinations of Control: Ownership and Function Based Entry Modes Ownership / Function Acquisitions Joint Ventures Total
Minority Ownership Minority Acquisition 118 (5.66%)
Minority Joint Venture 173 (8.30%)
291 (13.96%)
Majority Ownership Majority Acquisition 161 (7.72%)
Majority Joint Venture 647 (31.03%)
808 (38.75%)
Equal Ownership Equal Acquisition 17 (0.82%)
Equal Joint Venture 969 (46.47%)
986 (47.29%)
Total 296 (14.20%) 1789 (85.80%) 2085 (100%)
Cultural variables are summarized using composite cultural distance (CCD), calculated
according to Kogut and Singh’s (1988) aggregated equation. Control variables include Legal
restriction (LEGALRE), a measure for institutional influence in the host country coded 1 for
ownership restriction if an international joint venture before 1990, and 0 otherwise; coded 1 if a
foreign acquisition before 1995, and 0 otherwise (cf. Gomes-Casseres, 1999; Barkema &
Vermeulen, 1998). Timing of entry (TIMING) is used as a measure of institutional change over
time, measured as the number of years from January, 1985 to the venture's founding. Firm size
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(FMSIZE) is coded as 1 if the foreign firm is listed in 2002 Global 1000 of Business Week or
2002 Fortune Global 500, and 0 otherwise (cf. Pan, 2001).
The model for utility U of each of the six possible joint choices of function (acquisition
or joint venture) and ownership (minority, equal, or majority) is given generically as
U = (baseline constant utilities) + (effects of CCD on function, ownership and interaction)
+ (effects of LEGALRE on function, ownership and interaction)
+ (effects of TIMING on function, ownership and interaction)
+ (effects of FMSIZE on function, ownership and interaction) + ε.
Dummy variable parameterizations are described above. A stepwise variable selection
procedure using the α=.05 threshold was employed, considering interaction terms and main
effects tests as groups, rather than individual variables, where appropriate (cf. Agresti, 2002:
214-216). For example, the two interaction terms that measure the effect of CCD on interaction
are tested as a group using the likelihood ratio chi-square test with two degrees of freedom,
rather than tested separately using singe degree of freedom tests. “Effect heredity” is enforced,
wherein lower-order terms are retained whenever higher-order terms are retained (Hamada &
Wu, 1992). The resulting estimated model shows that CCD and LEGALRE affect function and
ownership but not their interaction, that TIMING affects function but not ownership, and that
FMSIZE affects the interaction of function and ownership. The parameter estimates and
standard errors of the resulting model for composite cultural measure are presented in the first
column of Table 5.
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Table 5. Comparison of bivariate model with univariate models to predict market entry Bivariate Model Univariate Model
(Function) Univariate Model
(Ownership) Variable Effect on β̂ s.e. β̂ s.e. β̂ s.e.
CCD Acq./JV -0.286 0.061 -0.362 0.057
CCD Low/Equal -0.213 0.061 -0.343 0.055
CCD High/Equal -0.105 0.045 -0.171 0.042
LEGALRE Acq./JV 4.277 0.455 3.710 0.388
LEGALRE Low/Equal -0.742 0.439 0.898 0.392
LEGALRE High/Equal -1.377 0.381 -0.500 0.357
TIMING Acq./JV 0.409 0.026 0.410 0.026
TIMING Low/Equal 0.139 0.025
TIMING High/Equal 0.067 0.019
FMSIZE Acq./JV -1.892 1.037 -0.557 0.186
FMSIZE Low/Equal -0.510 0.204
FMSIZE High/Equal -0.004 0.112
(Acq,JV)/ FMSIZE
(Low,Equal)
2.176 1.075
(Acq,JV)/ FMSIZE
(High,Equal)
1.100 1.060
Model Fit Statistics
Log Likelihood -2551.84 -2953.22 -3477.03
AIC (lower is better) 5137.68 5916.44 6970.06
Estrella (1998) R2 0.745 0.569 0.227
Comparisons with bivariate model
χ2=802.76,df=12 χ2=1850.38,df=9
It is clear from the fit statistics that the bivariate model has much greater explanatory
ability. In addition, the estimated bivariate model shows that FMSIZE affects interaction
between function and ownership; this conclusion is not formally possible (i.e., in a way that
allows significance testing) with the univariate models. The effect of FMSIZE on interaction is
shown in Figure 1.
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Figure 1. Log odds ratios for FMSIZE effect
-2
-1
0
1
Acq
JV
Acq -0.226 -1.892 -0.796
JV -0.51 0 -0.004
Low Equal High
Among contracts that ultimately end as joint ventures, firm size has little effect.
However, among contracts that ultimately end as acquisitions, the effect of larger firms is to
greatly reduce the odds of equal ownership.
An additional striking contrast between the univariate and bivariate models is that the
estimated effects of LEGALRE are quite different. In the bivariate model, the presence of legal
restrictions is estimated to decrease the odds of low versus equal ownership, while in the
univariate model, the reverse is true. It is important to note that interpretation of the parameters
in the joint model are interpreted as effects within levels of the function variable, while in the
univariate model the estimates refer to data pooled over the levels of function. As seen in Tables
1 and 2, pooling can have disastrous effects, as is well known from Simpson’s paradox.
While we have argued that the bivariate model is an improvement over the univariate
models, the main results concerning effects of cultural distance are essentially unchanged no
matter which model is used. However, an interesting finding not reported in the literature is this:
because the effects of CCD on Low/Equal and High/Equal are both significantly negative, we
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conclude that the larger the cultural distance between the home and host countries, the more
likely that selects an equal ownership entry mode is selected, rather than a majority or minority
ownership mode. To make this effect more clear, in Table 6 below we show ownership structure
among firms with cultural distance less than the median (2.9534), and among firms with cultural
distance greater than the median. The greater likelihood of equal ownership with High CCD is
apparent. Further, this nonlinear “upside-down U shaped” effect of CCD on ownership
illustrates the need to consider ownership as an unordered categorical variable, despite its ordinal
nature.
Table 6. Ownership Distribution by Composite Cultural Distance Ownership Low CCD* High CCD Minority 130 (16.3%) 161 (12.5%) Majority 346 (43.4%) 462 (35.9%) Equal 322 (40.4%) 664 (51.6%) Total 798 (100%) 1287 (100%)
*Because the number of countries is limited, there were a number of firms having CCD=2.9534 exactly, leading to only 798/2085 = 38% of the firms in the “Low CCD” category rather than ~50%.
Conclusion
We have developed a model for the case where there are multiple unordered categorical
dependent variables. The model is simple to specify and estimate using existing software, and is
flexibly and parsimoniously fit by selecting among interaction effects, similar to an ANOVA.
The model is recommended in cases where responses are jointly endogenous, failure to do so can
result in biases in univariate models caused by pooling. Because the model offers a
comprehensive framework that encompasses univariate models, it provides a unifying
framework for research streams within organizational research including market entry and
gender/race discrimination.
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Specifically, the model we have developed has the following benefits for analyzing
categorical responses jointly (as opposed to performing separate univariate analyses):
• Parameter estimates and standard errors from the corresponding univariate models are
obtained exactly from the multivariate model by dropping appropriate terms. Thus, the
univariate models results all are obtainable within the more general multivariate framework,
allowing formal model comparisons.
• When the predictor variables affect the interaction between the dependent measures, the
univariate analyses can be grossly misleading, but the multivariate analyses are accurate.
• The multivariate model allows that one predictor can affect one response and not the
other, within a single model, allowing joint efficient estimation of “seemingly unrelated
regressions.”
• The multivariate model includes main effect-type terms, two-way interactions, three-
way interactions, etc., allowing for exploratory parsimonious model selection by eliminating sets
of interaction parameters en masse, as in higher-way ANOVA modeling. For confirmatory
analysis, all model terms can be pre-specified; the ANOVA framework of the multivariate model
facilitates confirmatory model development.
• Composite tests of hypotheses across the set of response variables are easily available,
e.g., one can test the composite hypothesis that organizational unit has no effect on (gender, race)
combination, controlling for appropriate exogenous terms. These tests are often more powerful
than the univariate component-wise tests because (a) they combine information, in a meta-
analytic sense, and (b) when reduced form models are used, there are fewer degrees of freedom,
allowing focused tests, rather than diffuse tests that occur with over-parameterized models.
Dependent Categorical Variables
21
This paper has illustrated and highlighted a model that can be used to analyze multiple
unordered categorical response variables. Given the ease of implementation of these methods,
and the potential for improved analysis, it is hoped that this paper will encourage researchers to
analyze organizational data using models for multiple unordered categorical response variables
whenever their categorical measurements are simultaneously endogenous.
Dependent Categorical Variables
22
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