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.M414
no.
Wo
ALFRED
P.
WORKING PAPER
SLOAN SCHOOL OF MANAGEMENT
On the Persistence of
researchers in
Technological development
Raghu Gajud
Nfw
York University
Michael A. Rappa
Massachusetts Institute of
Technology
December 1991
Sloan
WP # 3395-92
MASSACHUSETTS
INSTITUTE OF TECHNOLOGY
50 MEMORIAL DRIVE
CAMBRIDGE, MASSACHUSETTS 02139
Massachusetts Institute of Technology
On the Persistence of
researchers in
Technological development
Raghu Ganid
New
Michael A. Rappa
York University
Massachusetts Institute of
Technology
December 1991
©
I99I
Sloan
WP # 3395-92
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
Alfred P. Sloan School of
Management
Massachusetts Institute of Technology
50 Memorial Drive, E52-538
02139-4307
Cambridge,
MA
T
'm
!
9 1992
On the Persistence of
Researchers in
Technological development
Raghu
New
GARUD
Michael A. RAPPA'*'
York University
Massachusetts Institute of
Technology
December 1991
ABSTRACT
Researchers often persist in their efforts to create knowledge that shapes the
development of a technology. By persisting, researchers can master a
knowledge and then contribute to its development. However,
persistence can be detrimental to researcher's careers
the organizations they
to
work
for.
This
obsolescence of existing stocks
is
and
stock
of
undue
the well-being of
because undue persistence can lead
of technological knowledge. Specific
hypotheses on persistence are developed
and
tested using the scientific
and
technical literature to determine the length of association of individual
researchers.
introduction
New
engage
fields
in
of science and technology emerge through the effbns of researchers
problem solving
activities.
These
efforts lead to the creation
techniques that represent technological knowledge (Allen,
who
of ideas and
1966; Layton, 1977:198;
Rosenberg, 1982:143; Laudan, 1984). Accordingly, the study of technological change
becomes one of understanding the creation and diffusion of knowledge among
practitioners.
A
widely accepted model of the growth of knowledge
is
one that views
it
as
a
cumulative progression of ideas and techniques (Crane, 1972:26). Antecedent ideas and
techniques influence the choice of future problems (Dosi, 1982). Success in solving these
problems depends upon the acquisition of relevant experiences over time. These
experiences translate into "rules of
thumb"
and Winter, 1982) that researchers employ
(Sahal, 1981:11 1) or "search heuristics" (Nelson
to address their technological problems. In this
of authors is arbitrary. Raghu Garud is assistant professor of
Stem School of Business (40, West 4th Street, Room 623, New York, NY
10003; tel. 212-998-4123). Michael Rappa is assistant professor of management, Massachusetts Institute of
Technology, Sloan School of Management (5t) Memorial Drive, Cambridge, MA 02139; tel. 617-2533627). The authors are indebted to Susan Bjorner and Gary Quick for their assistance in creating the database
and Joel Baum, Hayagreeva Rao and Robert Yaffee for their comments and guidance.
'
This work
management,
is
fully collaborative; the listing
New York
University,
way, technological progress
is
a cumulative problem-solving process with only infrequent
major disruptions (Rosenberg, 1982: 63).
The cumulative growth of technological
behavior of researchers
who produce
it.
icnowledge has important implications for the
In panicular, researchers
core stock of knowledge before they can contribute to
that
it
may
take anywhere
up
to ten years to
its
become an
its
need to master a
first
growth. Herben Simon estimates
That
expert in an area of work.
researchers have to persist in their efforts to develop a
contribute to
may
new technology
in
is,
order to
development.
Recognizing the benefits of persistence, Ziman (1987) nevertheless cautions against the
decreasing marginal returns firom undue persistence. According to
Chubin and Connolly
(1982), researchers persisting unduly with an area of work in order to leave a research
Over time,
trail.
of behavior leads to incremental yields from a stock of knowledge.
this type
The danger of undue
become
obsolete, thereby
Indeed,
many
persistence
is
that existing researchers' stock of
knowledge may
undermining the well being of the organizations they work
scholars have witnessed the creation of
researchers from outside the system.
new
for.
technological knowledge by
These "outside" researchers
offer ideas that
may run
new knowledge
counter to existing mainstream technological knowledge. If successful, the
displaces existing knowledge.
What
determines researchers' persistence with a technology? While an important
question that has clear implications for the
question has so
far
management of
R&D
not been examined empirically. In this paper,
we
organizations, this
use the literature as a
source of data on the length of researchers' association with a technology to examine
persistence behavior. Persistence,
collective aspects
Persistence
is
also influenced
we
suggest,
depends upon individual,
relational
of the knowledge creation process that technological change
by the occurrence of important events
technology that legitimize
persistence,
we
first
it.
in the
Before proceeding to develop and
and
entails.
development of a
test
hypothesis on
provide an overview of the knowledge creation process within a
community of researchers.
RESEARCH COMMUNITIES AND THE CREATION
OF TECHNOLOGICAL KNOWLEDGE
In Introducing the trade-offs between persistence and undue persistence, researchers
were deliberately portrayed
as
individuals working independently on
technological
problems. However,
relationships with
competencies
it
more
is
in collaborative
address complex indivisible technological problems (Metcalfe
and Soete, 1983) that researchers individually may not able
The
working
one another. Collaboration between researchers possessing different
vital to
is
realistic to visualize researchers as
to address.
creation of knowledge by researchers engaged in collaborative relationships with
others results in a steady accumulation of knowledge that other researchers can build upon.
From
this perspective, the creation
of a new technology
MacDonald's (1978)
illustrate the collective
knowledge creation
cnuils.
the
it
produa of three men,
They point out
is
a colleaive endeavor.
Braun and
nature of technological change and the
that
it
is
unrealistic to see the transistor as
or of one laboratory, or of physics, or even of the forties. Rather,
the development of the transistor required contributions from hundreds of researchers,
working
many
in
different places, in
Technological knowledge
as
many
different fields, over
a collective
endeavor
years.
becomes manifest
also
acceptance of practices that become institutionalized within a
community of
inscription devices (Latour and Woolgar, 1979),
These
and other taken
momentum
(Hughes, 1987) that
researchers join a technological field, there
technological knowledge
is
is
attracts other researchers.
its
creation
benefits.
As
an increase in the rapidity with which
created.
and
fraught with externalities; that
its
and
for granted faas
Technological knowledge has another collective property that has
appropriate
1987),
institutionalized practices legitimize a technology, thereby creating the
necessary technological
implications for
the
in
researchers
1983). These practices consist of testing standards (Constant,
(Jagtenberg,
artifacts.
many
The
is,
diffusion. In particular, the
even those
who have
important
knowledge creation process
not contributed to
its
creation
is
may
presence of externalities leads to the rapid diffusion of
technological knowledge. However, the presence of externalities also reduces the incentives
for the private
rights,
produaion of knowledge. Despite mechanisms such
knowledge does leak out
to others.
imponant
property
As a consequence, Nelson (1959) and Arrow
(1962) have argued that the private production of knowledge
community perspcaive. Under
as intelleaual
may be sub-optimal from
a
these circumstances, researchers in the public sector perform
roles in the creation
and dissemination of knowledge (Rosenbloom, 1966;
Mueller, 1962; Utterback, 1975; Stobaugh, 1985). Besides engaging in research aaivities,
researchers in public institutions identify
knowledge.
and fund private
institutions for the creation of
Rappa and Debackere (1991) introduce
the notion of researcher
community
to integrate
these various facets of the knowledge creation and diffusion process. Building
Constant's (1980) work, Rappa and Debackere define the researcher
of
scientists
and engineers who
are
committed
technological problems. These researchers
communicate
community, knowledge creation
is
collaborative
relationships
determined by individual,
a colleaive
diffusion process within this
and
community.
in
some way with each
and
other.
Within the
endeavor driven by individuals engaged
collective aspects
We
group
organizationally dispersed in public and
with others. Consequently, persistence
relational,
as a
to solve a set of inter- related scientific
may be
private seaor organizations but
community
upon
is
in
in
some way
of the knowledge creation and
explore these aspects in greater detail in the
next seaion.
DETERMINANTS OF PERSISTENCE
Analogous
to
Kuhn's (1970) notion of anomalies
in science.
Constant (1987) introduces
the notion of presumptive anomalies that occur in the development of technologies.
Presumptive anomalies occur when assumptions derived from science indicate that a
or that a radically different technology will be
conventional technology will
fail,
effective (Constant, 1980:15).
The
identification of presumptive anomalies
may
more
result in
the displacement of established technologies and the knowledge systems they entail.
Existing researchers resist these discontinuous changes because of career
their
own
new
technology, researchers also
commitments
to
technologies. Besides this instrumental reason for resisting the introduction of a
resist
changes for cognitive reasons.
The new
stock of
knowledge represents a new technological paradigm (Dosi, 1982), or regime (Nelson and
Winter,
1977), with
its
associated traditions of testability (Constant,
1987). Dosi
(1982:153) points out that these paradigms have a powerftjl "exclusionary effea" rendering
researchers blind to alternative technological possibilities.
Confronting resistance from researchers embedded
paradigm, the
new technology can only grow with
researchers to pursue the
draw upon the
skills
an existing technological
the efforts of a few dedicated
development of the new technology. These pioneering researchers
and knowledge of researchers from other
peripherally connected with the development of the
connected researchers
in
may make
without committing themselves to
new
disciplines
who may
be
technology. These peripherally
transient contributions to the emerging technology
its
long term development.
Transient contribution behavior from these peripherally connected researchers
its
own
value during early periods of technology development. However, sustained
contributions from a growing
commit themselves
number of researchers
new technology
technology. As long as the
to
to developing
it.
Constant (1987)
offers the
new
technological field
commitment.
new
as
one approach by which
technology. Traditions of testability consist
technological practice. Akin to the formation of a
the
new
of testing techniques and normative values that sustains and defines the
traditions of testability help researchers
new
lacks legitimacy, researchers will be unwilling
notion of traditions of testability
legitimacy can be established for the the
set
are necessary for the success of the
Events that legitimize the
are therefore critical to induce researchers'
of a
may have
new vocabulary and
a
specific
grammar, these
communicate with one another and
to legitimize
technology.
Technologies also can gain legitimacy from the actions and statements of powerful
institutional organizations.
from
include: seed capital
Examples of events that serve
federal
to legitimize technologies
funding agencies, endorsements from regulatory bodies,
and the formation of professional organizations. In combination with the formation of
traditions of testability, these events that lend legitimacy to the
increasing the
H
1
:
commitment of researchers
Researchers are
more
to the
new technology
result in
development of the technology.
likely to persist in their efforts to develop
a technology in a
legitimized field.
Besides these events that legitimize the
new
technological field, the presence of a
critical
mass of researchers may be required to establish technological momentum. Size
confers
power and
community's
prestige to the
emerging community. Power and prestige
ability to generate resources
researchers in their
problem solving
once the community
size increases
result in the
from the environment that sustains individual
efforts.
Thus, researchers are more
beyond a threshold
limit as a
likely to persist
bandwagon effea occurs
(Rappaand Debackere, 1989).
H2: Researchers are more likely to persist in their
development of a critical mass of researchers.
Over time, praaices followed by
community and begin
efforts to
these researchers
develop a technology after the
become
institutionalized within this
dictating the direction of future research. Representing collective
specialized stocks of knowledge, these practices
become
accessible only to those
who
undergo professionalized education and training. As investments required to enter the
community
increases,
it
becomes more
who
contribution behavior. As a result, researchers
community
anempt
will
for researchers to
difficult
join a professionalized
to leverage their entry investments with
H3: Researchers' persistence
likely to increase
is
exhibit transient
research
ongoing contributions.
with the accumulation of knowledge within
a technological field.
Individual researchers
emerging
paradigms
may pursue
(Dosi,
different technological trajectories within these
Trajectories
1982).
represent
directions
specific
of
technological change based on researchers' theoretical assumptions and the physical
they employ. Early during the development of a technology, researchers hold
artifacts
about "what
different beliefs
is
feasible or at least
worth attempting" (Nelson and Winter,
1982:258-259). Because of the uncertainty and ambiguity associated with technological
choices, researchers "place their bets"
Over
build
up
on
different trajectories.
time, researchers develop technology specific competencies. These competencies
in a path
dependent manner (Cohen and Levinthal, 1990; Arthur, 1988; David,
1987) as earlier technological choices direa future options and solutions. As competencies
become
specialized, researchers find
it
increasingly difficult to re-deploy
them
to pursue
other trajectories, or to pursue other technological paradigms. As a consequence, there are
powerful incentives for researchers to persist with a trajectory.
Thus, an important determinant of persistence
technology
itself
Gieryn's (1978)
work supports
is
the longevity of association with the
this hypothesis.
Studying the published
work of American astronomers over the period 1950-1975, Gieryn found
who had
published a paper on a particular specialized subjea were likely to continue
publishing in the same area for
length of
that researchers
many
years. Similarly,
Mullins (1972) found that the mean
membership of a Phage group of researchers was about three
six years if
those
who
years,
but doubled to
published only one paper on the subject were excluded.
H4: The likelihood ofpersistence in the development of a technology increases with
duration of researcher's association with a technology.
So
far,
we have examined
individual
and collective dimensions that influence
persistence of researchers. Besides these dimensions, persistence
relational
aspects that capture the extent to
is
also
determined by
which researchers associated with the
development of a technology collaborate with one another. Collaboration represents the
joint creation
of ideas by individuals. In a recent study of a bio-medical research
community, Small and Greenlee (1986) found
that collaboration
between researchers
increased steadily over the ten year period that they studied. Beaver and Rosen (1979)
found
panern of increased collaboration from
a similar
concluded
growth
the
that
of collaboration
to
They
their study of scientists.
be
natural
a
consequence
of
professionalization.
ProfessionaJization implies the division of labor and specialization
The
specialized division labor of requires collaborative efforts
where
among
researchers.
different skills can
be brought to bear to address complex technological problems (Ziman, 1987; Jagtenberg,
1983). Collaboration thus increases the reach of individual researchers, thereby allowing
them
to penist with their contributions.
H5: Researchers are more
likely to persist in their efforts to
develop a techno loQi if they
collaborate with others.
RESEARCH SITE
We
chose the
field
of cochlear implants
as
an
illustrative case for the present analysis.
Although studies of the elearical stimulation of the ear have a long
the 1950s that researchers began the systematic investigation of
might provide
of sound.
a
One
means
result
history,
how
it
was not
electrical stimulation
for enabling people with sensorineural deafness to gain
of
this research
until
some
sense
was the advent of the cochlear implant, a device that
uses elearical stimulation of the cochlea to provide a sense of
sound
to profoundly deaf
people.
One
of the
first trials
1961 by William House, a
of a rudimentary cochlear implant devices was performed
clinical physician,
who
major center for cochlear implant research. At
later
first,
founded the House Ear
Institute, a
few researchers took an interest
cochlear implants, largely due to the intense controversy the field encountered.
considered the device to lack a scientific basis and believed
human
experimentation.
It
was not
until the early
cochlear implants emerged as a viable research
that galvanized the burgeoning field.
it
in
in
Many
was too premature
for
1970s that the controversy subsided and
field.
Several meetings were held in 1973
These meeting included a workshop held
as part
of
the American Otological Society meeting (a group that was adamantly opposed to the
topic in previous years)
One
and the
study of importance
first
is
international conference
Bilger's
work
on the
initiated in
subject.
1975 on the comparative
performance of cochlear implants. Funded by the U.S. National Institutes of Health and
released in
1977, the "Bilger report" (1977) showed that although the early claims
regarding performance were exaggerated, cochlear implants did have merit.
conclusion, the report lent
hundred individuals
active
organization world wide.
S.
sorely
needed legitimacy
number of researchers
the door for a greater
located in the U.
some
in
By 1991,
its
and thereby opened
to the field
to participate.
In
there were about four
the field employed in nearly one hundred different
About
community
forty percent of the cochlear implant
Although tremendous progress has been made over the
years,
is
and about
three thousand patients have received the cochlear devices, the cochlear implant remains
largely
an experimental procedure with
many
challenging problems yet to be overcome.
DATA COLLECTION AND METHODS
Gathering longitudinal data on researcher persistence
First,
it
requires
some degree of
historical investigation. If
presently works in a particular field
the experience of
many
how
individuals
Second, the number of researchers
who have
who have
who
ask everyone
it
who
we would overlook
over the years.
participated in a field can be quite large
and
very hard to ascertain the extent
it
become appealing
participates in a field
conference papers and patents in a given
articles,
we simply
come and gone
already
of their participation. Confronted with these constraints,
the literature as a source of data about
not a simple task.
is
long they have participated,
can be widely dispersed geographically thereby making
Journal
in a field
and
for
how
to look to
long.
field represent a detailed, self
reported archival record of the effon generated by researchers to solve the scientific and
technological problems confronting them. Furthermore, the literature
is
an appealing
source of data in several respects: the publication conventions ensure a level of quality and
authenticity; the data can be collected unobtrusively; the findings can be replicated
tested for reliability;
When
and the data
taken together, the literature can be viewed
researchers to establish a
involved,
with,
are publicly available
how
new
field,
as
and not very expensive
and can provide information about the researchers
long they were involved, where they were employed,
difficult to
to collea.
a unique chronology of the efforts of
what problems they pursued, and when they were
would be
and
who
they collaborated
active in the field. Clearly,
it
match the comprehensive scope and longitudinal nature of the
literature using other data collection techniques.
Data collection Five commercial electronic databases (covering the medical
.
and engineering
literature)
were used to identify publications related to the
sciences
field
of
cochlear implants.
be
The
commonly used
be either
in the lexicon of cochlear
research bibliography
The
earlier
to
implant researchers. These key terms might
or classification terms of a document.
in the title, abstract
was derived from an
known
databases were searched using a set of key terms that are
The
search strategy
one used by the National Library of Medicine
to create a
on cochlear implants.
data colleaion procedure resulted in the identification of 1329 unique documents
relating to cochlear implants published
used to identify each researcher
This procedure yielded a
who
total
between 1973 and 1989.
The
data base was then
contributed to the field over the seventeen year period.
of 1,257 researchers.
A
statistical
database was created
containing several individual-, relational-, and population-level variables for each
researcher that was derived ft^om information obtained from published documents.
Dependent
variable
publications in a field
.
The number of years spanning
—
that
is
the "contribution span"
measure of researchers persistence
The primary
—
some methodological
issue
serves as a
of concern
since the individual have not yet left the field,
is
some minimum value
for this, survival analysis statistics
(that
and
known
last
unique and
usefiil
is
it
who presendy
that for those researchers
is
is
only
is
issues that arise that require
are active in cochlear implants, the overall length of contribution
contribution
first
Although calculating the contribution span
in a field.
relatively straightforward, there are
fiinher explanation.
a researcher's
known
is
indeterminate: that
is,
that the length of their
the entry year to the present year).
To
account
were used to analyze the data. Such techniques take into
consideration precisely this kind of problem in the calculations with a procedure that
adjusts for the biases that right censored data create.
Determining
reason for this
is
if
a researcher
is
that researchers
still
may
active can be difficult in certain conditions.
The
not publish every year. Therefore, a researchers'
contribution span in the field can be charaaerized by gaps of several years in duration in
which there are no publications
to their credit.
publication records raise the issue of
how
The
frequendy a researcher must publish
be considered an aaive contributor to the
field.
proper censoring scheme to use in the analysis.
this
question
is
is
it
The
is
order to
question
important in determining the
arises:
How long
reasonable to assume they are no longer in the field?
necessary in order to determine
in
Thus, understanding the nature and the
prevalence of gaps in a researchers' contribution span
ceases to publish
existence of discontinuities in
who
has exited the field and
after
someone
The answer
who
persists.
to
10
The
cochlear implant data shows that 242 (19%) researchers have a gap in their
contribution spans.
Among
those
who
have a gap
in their
contribution spans, four out of five
on
researchers have a gap of three years or less in duration. Based
that researchers
who had
this evidence,
published within the past three years of the
last
we
decided
year of the data set
(1989) would be censored.
Only
number (3.7%) of
a small
the researchers have a gap between publications of
all
longer than three years in duration. These sparse contribution spans
individuals
who do
having
left
the field
begin a
new
if
Explanatory
We
treated these researchers as
they again started contributing.
variables
among
field.
be indicative of
they did had contributed during a three year period, and as having
when
cycle
heterogeneity
not contribute continuously to the
may
.
Several
These include the kind of organization
researchers.
researcher was employed.
were created that might account for
variables
These researchers were coded according
to
in
which each
whether they
reside in
an academic, industrial, government or independent research laboratories.
Besides these variables, other explanatory variables were created to test the four
hypotheses developed on contribution spans.
To
test for
the hypothesis on legitimacy, a
variable was created to distinguish between a pre-legitimacy period (considered to be
prior to the publication of the Bilger
repon
in
1978) and a post-legitimacy period
after
1978.
To
test for the
hypothesis on
was created. Population
published in the
to capture
field in a
size
critical
mass, a variable that measured the population size
measured
is
given year.
A
in
number of
terms of the
researchers
second order population variable was
any quadratic associations between population
size
who
also created
and contribution spans.
Besides these two variables, a third variable at the population level was created to control
for possible influence
of dispersion of researchers
persistence. This dispersion variable
among
measured the extent
different organizations
to
which the community
on
is
concentrated in a few organization or spread across many. For this purpose, a Hirfindahl
determined by calculating the sum of the squared share of researchers
statistic,
which
aiFiliated
with each organization
A
variable
is
is
used.
was created that represented the accumulated knowledge
determined by the cumulative number of publications to
of knowledge in the
field.
To
test
test for
in
the field as
the hypothesis on growth
the hypothesis at the individual level, a variable that was
11
the time of researchers' association with the technology was created.
Chubin and Connolly
(1982) suggest a potential alternative explanation for individual persistence. They point
out that persistence can be a result of positive feedback relationship between
and
researchers
from the environment.
their ability to gather additional resources
we developed
control for this alternative explanation,
successftjl
To
measure of the cumulative
a
productivity of individual researchers.
Collaboration was measured by the
associated with as a co-author
on
number of unique
To
publications.
individuals that a researcher had
control for other potential group level
explanations, two group level variables were created to reflea the size and produaivity of
The
a researchers' institutional affiliation.
of the nimiber of individuals
affiliated
Cumulative group produaivity
size
with that organization
measured
is
of a researcher's group
as
who
the cumulative
is
measured
terms
in
also publish in the field.
number of
cochlear implant
publications by individuals affiliated with a researchers' group.
MODELING STRATEGY AND RESULTS
Model Event
:
history
methods were used
implies a lower probability of exiting a field conditional
Persistence
association.
The
instantaneous exit
conditional probability of exiting the field
rate, also
known
as the
r.(t)=
exit rate at
time
t
X(t)
is
lim
rate,
upon
earlier
the exit rate.
is
The
is:
P^(t,t^At/t)
At
was modeled by estimating the following specification:
ri(t)
Where
hazard
^->0
'
The
to study persistence behavior of researchers.
= exp [aiX(t)]
a vector of the values of the covariates at time
t,
and
ai is
a vector of
parameters. In this model, hazard rates are postulated to be log-linear functions of the
In order to incorporate time variations in the explanatory variables, a
variables X.
multiple-spells formulation of this
each period
exiting.
is
broken
down
model was used. In the multiple
into one-year observations in
Each of these annual
spells
is
spells
formulation,
which the researcher
is
at risk
of
treated as being right censored unless the researcher
12
exits.
RATE (Tuma, 1980) was
method of maximum
Results
.
used to estimate the vector of parameter estimates by the
likelihood.
The model was
estimated in a sequence of steps by adding sets of explanatory
variables into the equation (see
Table
among
included to control for variations
The second model
affiliation.
First, variables
1).
pertaining to researcher type were
researchers' persistence because of organizational
included the length of researchers' association along with
the variable
on cumulative productivity. This model was estimated
persistence
may
phenomenon
age dependent
be an
to identify
controlling
after
for
whether
possible
heterogeneity of the sample, and controlling for researcher success and reputation as
measured by the cumulative produaivity
tested hypotheses
were
variables
The
also
1
As explained
introduced
at
rises
covariates
from 18
on the
Model
exit rate.
Model 6 even though
The
in
For
results
in
Models 3
to
6 added variables that
the methods section, appropriate control
each step.
results indicate that the
The X^
among
to 4.
variable.
fit
1
this
of the models improved
to
614
paper
Model
in
we
6.
as covariates
Model 6
focus our attention
were included:
displays the effeas of
on the
all
results displayed in
of other models are provided for a comparison.
results indicate that the hypothesis relating to collaboration
the five that did not receive support.
One
reason for this
is
was the only one
that collaboration as
measured by the number of cumulative co-authors does not adequately capture the entire
spectrum along which researchers collaborate. Nevertheless, the lack of significance
suggests that relational aspects are less of a predictor of persistence. This conclusion
bolstered
by the lack of significance of other group
level variables,
including group
is
size
and group productivity.
The
results
do support other hypotheses. For instance, the positive sign of the
legitimacy variable suggests that the likelihood of persistence increased after 1978 with
the publication of the Bilger Report that served to legitimize the cochlear implant field.
Similarly, there
is
support for the
critical
mass hypothesis. The positive coefficient of the
population variable combined with the negative coefficient of the second order term
implies an inverted U-shaped relationship between population size
Critical
and the hazard
mass appears to have been accomplisheed with a population
researches (which occurred in 1983) at
which point the hazard
size
rate decreases.
rate.
of around 213
13
In support for the hypothesis relating to knowledge accumulation and persistence, the
variable that reflects the cumulative publications in the field was
with a negative
knowledge
The
That
sign.
to be significant
the risk of leaving the field decreases as the accumulated
increases.
significant negative sign of the length of association variable indicates that
researchers
may have
a
tendency to
productivity of researchers.
time,
is,
found
we conduaed
To
persist
with time despite controlling for the cumulative
further explore individual determinants of persistence over
a non-parametric analysis of the hazard flinaion based
of researchers' association. For
procedure LIFETEST
this
(see Figure 1).
purpose,
we used
on the duration
the lifetable approach in SAS (v5.18)
14
CONCLUSION
The objeaive of
paper was to empirically explore persistence behavior of
this
development of a technology. Non-parametric estimates of
researchers associated with the
the analysis of persistence through a hazard analysis shows that the risk of exiting the field
is
About 40-percent of the
greatest in the first year of their contribution.
researchers
one year
associated with cochlear implants demonstrate transient persistence for only a
The
duration.
hazard rate declines sharply after the
which
until the sixth year after
it
and by the
thereafter for
more
fertile territory.
program might be
a research
data collection and analysis.
by the prospea of making an
at either, the researcher
But
if
established;
By
to a field
might
It is
once
in place
it
would require
the end of the sixth year, a
among
exit the field shortly
the researcher can initially "survive" in the
critical
which time the success of the program leads the researcher to remain
probability of ever leaving.
of the research
possibility of attracting the resources to underwrite the
of his or her work. Barring success
cost
in a behavioral characteristic
For example, a researcher might be drawn
imjX)rtant contribution
year and remains fairly constant
continues to decline rapidly.
This result might have an explanation
process.
first
field,
several years
point
is
of
reached, at
in the field
with linle
these latter category of researcher that
we would
look for undue persistence.
Modeling the instantaneous
exit rate
with parametric
statistics
provided other insights
about persistence. Early during the development of a technology, persistence
associated with the legitimacy of the technology
During
this stage, the creation
and the
of technological
size
momentum
is
strongly
of the research community.
has very
much
to
do with
whether or not individuals are ready to commit themselves to the emerging technology to
sustain
its
growth. Over time, a reversal occurs wherein accumulated knowledge results in
creating strong incentives for researchers to persist.
What
is
collaboration
perhaps
most interesting
is
that
relational
aspects
including direct
and other forms of collaboration including group membership and group
produaivity do not appear to be key determinants of persistence. Persistence thus appears
to be
with
determined by individual
its
an emerging professionalized
field
concomitant norms for the creation and diffusion of technological knowledge
opposed to intermediary
This
efforts to contribute in
is
relational aspects
as
of the knowledge creation process.
a preliminary analysis that sets the base for the exploration of
more
fine-
grained processes connected with researcher persistence. For instance, data from the
15
cochlear implant literature have been gathered with respea to the nature of the
conduaed by each
clinical research),
researcher (such as basic research, applied research, development, or
and the panicular technological trajeaory each researcher has pursued
(such as single-channel versus multi-channel devices).
funding
levels
conduaing
work being
Other kinds of data such
as
annual
and the extent of the market commercialization have been collected
a subsequent analysis.
for
REFERENCES
Allen, T.J. 1966. "Studies of the problem-solving process in engineering design,"
Transactions on Engineering
IEEE
Managemmt, EM- 18: 72-83.
Arrow, K.J. 1962. "Economic welfare and the allocation of resources for innovative
aaivity," in R.R, Nelson (ed.) The Rate and Direction of Inventive Activity. Princeton:
Princeton University Press.
Arthur, B. 1988. "Self-reinforcing mechanisms in economics," in P Anderson
Economy
as
an Evolving Complex
Beaver D. and Rosen R. 1978. "Studies in scientific collaboration: Pans
Scientometrics, 1: 65-245.
Bilger, R.C., et
al.
et al..
The
System. Reading, Mass.: Addison-Wesley.
1,
2 &: 3"
1977. "Evaluation of subjects presently fined with implanted auditory
prosthesis," Annals of Otology, Rhynology,
and
Laryngology, 86, 3,
Pan
2,
Suppl. 38.
Braun, E. and MacDonald,
S. 1978. Revolution in Miniature: The History and Impact of
Semiconductor Electronics. Cambridge: Cambridge University Press.
Chubin, D.E. and Connolly, T. 1982. "Research trails and science policies: Local and
extra-local negotiations of scientific work" in Elias, N., et al. (eds.) Scientific
Establishments
and
Hierarchies. Dordrecht: Reidel.
Cohen, W. M. and Levinthal, D. A. 1990. "Absorptive capacity: A new perspective on
learning and innovation," Administrative Sciences Quarterly, 35, 1: 128-52.
Constant, E.W. 1980. The Origins of the Turbojet Baltimore: John Hopkins University
Press.
Constant. E.W. 1987. "The social locus of technological praaice:
organization?," in
Systems.
W.E.
Bijker, et
Cambridge, Mass.:
MIT
al.
(eds.)
Community,
system, or
The Social Construction of Technological
Press.
Crane, D. 1972. Invisible Colleges: Diffusion of Knowledge in Scientific Communities.
Chicago: University of Chicago Press.
David, P. 1985. "Clio and the economics of QWERTY" Economic History, 75: 227-332.
Dosi, G. 1982. "Technological paradigms and technological trajeaories," Research Policy
11:
147-162.
Gieryn, T.F. 1978. "Problem retention and problem change in science," Sociological
Inquiry, AS: 96-115.
Hull, D.L. 1988. Science as a Process:
An
Evolutionary Account of the Social
Development of Science. Chicago: University of Chicago Press.
and Conceptual
17
Hughes, T.P. 1987. "The evolution of large technological systems," in W.E.
(eds.) The Social Construction of Technological Systems. Cambridge, Mass.:
Bijker, et
MIT
al.
Press.
Jagtenbcrg, T. (1983), The Social Construction of Science: A Comparative Study of Goal
Direction, Research Evolution and Legitimation. Boston: Reidel Publishing.Co.
Kuhn, T.S. 1970. The Structure of Scientific
Revolutions. Chicago: University of
Chicago
Press (2d ed.).
Latour, B. and S. Woolgar. 1979. Laboratory Life: The Social Construction of Scientific Facts.
Beverley Hills: Sage Publications.
Laudan, R. 1984. The Nature of Technological Knowledge. Dordrecht: Reidel.
Layton, E. 1977. "Technology as knowledge". Technology
Mansfield, E. 1985
Economia, 34,
2:
"How
and
Culture, 15: 31-41
rapidly does a technology leak out?" Journal of Industrial
217-223.
J. S. and Soete, L. 1983. "Notes on the evolution of technology and international
competition," a paper presented at the workshop on Science and Technology Policy,
University of Manchester.
Metcalfe,
Mullins, N.C. 1972.
"The development of a
scientific speciality:
The phage group and
the
origins of molecular biology," Minerva, 10: 51-82.
Mueller,
W.F. 1962. "The
origins of the basic inventions underlying
product and process innovations, 1920-1950,"
in
R. Nelson
Du
(ed.)
Pont's major
The Rate and
Direction of Inventive Activity. Princeton: Princeton University Press.
Nelson, R. 1959. "The simple economics of basic scientific research". Journal of Political
Economy, 6: 297-306.
Nelson, R. and S.G. Winter. 1977. "In search of a useful theory of innovation," Research
Policy. 6:
36-76.
Nelson, R. and S.G. Winter.
1982.
An
Cambridge, Mass.: Harvard University
Evolutionary
Theory of Economic Change.
Press.
R&D
communities: Implications for technology
Rappa, M.A. 1989. "The dynamics of
strategy," working paper, MIT Sloan School of Management.
and Debackere, K. 1991. "R&D communities and technological
development," working paper, MIT Sloan School of Management.
Rappa, M.A.
Rosenberg, N.
1982. Inside the Black Box:
Cambridge University
Technology
and Economics. Cambridge:
Press.
Rosenbloom, R.S. 1966. "Product innovation
in
a scientific age,"
Successjul Marketing. Chicago: Proceedings of the
Marketing Association, Chapter, 23.
in
New
Ideas for
1966 World Congress, American
Sahal,
D. 1981 Patterns of Technological Innovation. Reading, Ma5S.: Addison-Wesley
Publishing
Small,
2):
Company.
H. and Greenlee,
E. 1986. "Collagen research in the 1970s," Scientometrics, 10 (1-
95-1 17.
Stobaugh, R. 1985. "Creating a monopoly: Product innovation in petrochemicals," in R.
Rosenbloom
New
Tuma, N.B.
Tuma
(ed), Research
on Technological Innovation,
Management and
Policy,
Vol
2.
York: JAI Press (81-112).
1980. Invoking RATE, (2nd
ed.).
Menio
Park, Calif.: SRI International.
N.B. and Hannan, M.T. 1984. Social Dynamics: Models and Methods. Orlando:
Academic
Press.
Utterback, J.M. 1974. "Innovation in industry and the diffusion of technology," Science,
183: 620-26.
Ziman,
J.
1987. Knowing Everything About Nothing: Specialization
Careers.
Cambridge: Cambridge University
Press.
and Change
in Scientific
19
TABLE
ML Estimation
Modell
Intercept
-1.5
1
of Contribution Spans
Mgdcl2
-.7
(0.06)
Models
-.7
(0.08)
(0.08)
Mociel4
-2.5
(0.45)
Models
-1.77
(0.47)
Model6
-1.8
(0.47)
Typt ef OrsjtnfsatJQn
Industrial
Research
Government
.001
.06
.1
.1
.07
.04
(0.26)
(0.26)
(0.26)
(0.26)
(0.26)
(0.26)
.13
.012
.03
-.01
-.01
.007
(0.1)
(0.1)
(0.1)
(0.1)
(0.1)
1.5
(0.38)
1.11
1.16*
.71
.58
(0.58)
(0.58)
(0.58)
(0.58)
(0.1)
.47
(0.58)
Geographic location
USA
-.03'"
-.22
(0.09)
(0.085)
Length of association
Cumulative researcher productivity
Legitimacy of
-.22
(0.08)
-.16
-.15
(0.09)
(0.09)
(0.086)
-.27"'
-.27'"
(0.05)
(0.04)
(0.05)
-.1"
-.1"
-.11'"
-.09"
(0.033)
(0.03)
(0.03)
(0.04)
.48""
1.33"'
2.17'"
2.15'"
(0.14)
(0.03)
(0.36)
(0.003)
.03"-
.03'"
.03"'
(0.00)
(0.00)
(0.009)
-.09"'
-.07'"
(0.01)
(0.01)
(0.004)
.001
-.or
-.009"
(0.002)
(0.002)
(0.001)
-.28
-.28'"
(0.046)
(0.046)
-.10"
(0.033)
field
-.02
Population
Popularion^/lOOO
Dispersion of researchers
-.29
-.0024"
Cumulative knowledge
(0.000)
Group
-.08'"
-.003'"
(0.003)
-.01
size
(0.012)
-.0007
Cumulative group productivity
(0.04)
-.017
Cumulative co-authors
(0.02)
P-leve!
Chi square
NOTE:
number of spells
= 2976;
.000
.000
.000
.000
4
6
7
10
11
14
18.0
263.7
273.8
540.7
610.0
614.1
number of exits
= 604.
1.)
Overall
2.)
Figures in parenthcics arc standard errors of estimates
3.)
Significance level:
'
< .05;
"
.000
.000
df
< .01;
"'
< .001.
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