ergm.count (version 4.1.2)

zach: Karate club social network of Zachary (1977)

Description

Zachary (1977) reported observations of social relations in a university karate club, with membership that varied between 50 and 100, of whom 34 individuals: 32 ordinary club members and officers, the club president ("John A."), and the part-time instructor ("Mr. Hi"); consistently interacted outside of the club. Over the course of the study, the club divided into two factions, and, ultimately, split into two clubs, one led by Hi and the other by John and the original club's officers. The split was driven by a disagreement over whether Hi could unilaterally change the level of compensation for his services.

Format

The data are represented as a network object, with an edge attribute contexts, giving the number of contexts of interaction for that pair of actors. In addition, the following vertex attributes are provided:

list("club")

the club in which the actor ended up;

:

the club in which the actor ended up;

list("faction")

faction alignment of the actor as recorded by Zachary

:

faction alignment of the actor as recorded by Zachary

list("faction.id")

faction alignment coded numerically, as \(-2\) (strongly Mr. Hi's), \(-1\) (weakly Mr. Hi's), \(0\) (neutral), \(+1\) (weakly John's), and \(+2\) (strongly John's);

list("role")

role of the actor in the network (Instructor, Member, or President)

Details

Zachary identifies the faction with which each of the 34 actors was aligned and how strongly and reports, for each pair of actors, the count of social contexts in which they interacted. The 8 contexts recorded were

• academic classes at the university;

• Hi's private karate studio in his night classes;

• Hi's private karate studio where he taught on weekends;

• student-teaching at Hi's studio;

• the university rathskeller (bar) located near the karate club;

• a bar located near the university campus;

• open karate tournaments in the area; and

• intercollegiate karate tournaments.

The highest number of contexts of interaction for a pair of individuals that was observed was 7.

References

Zachary, WW (1977). An Information Flow Model for Conflict and Fission in Small Groups. Journal of Anthropological Research, 33(4), 452-473.

Examples

data(zach)

oldpal <- palette()
palette(gray((1:8)/8))
plot(zach, vertex.col="role", displaylabels=TRUE, edge.col="contexts")
palette(oldpal)

# \donttest{
# Fit a binomial-reference ERGM.

zach.fit1 <- ergm(zach~nonzero+sum+nodefactor("role",base=2)+absdiffcat("faction.id"),
                  response="contexts", reference=~Binomial(8))

mcmc.diagnostics(zach.fit1)

summary(zach.fit1)
# }
if (FALSE) {
# This is much slower.
zach.fit2 <- ergm(zach~nonzero+sum+nodefactor("role",base=2)+transitiveties,
                  response="contexts", reference=~Binomial(8),
                  eval.loglik=FALSE)

mcmc.diagnostics(zach.fit2)

summary(zach.fit2)
}