larger sample sizes and, consequently, greater statistical
power, as each individual is used more than once. Tournament
designs, however, are not widely used because such
a design results in males having different agonistic experiences
and the effects of unmeasured differences in fighting
ability and ‘experience effects’ can be difficult to
disentangle. That is, a winner may keep winning because
he has a series of attributes that make him a better fighter
or because of a self-reinforcing ‘winner effect’ and vice
versa for losers.We show how this problem can be circumvented
through use of a generalized Bradley–Terry model.
Traditionally, the B–T model has been used to assign
ranks to individuals within a linear hierarchy based on
paired observations. The only two previous applications of
the B–T model to animal dominance or aggression used
the model to estimate a complete hierarchy, then tested
whether position in the hierarchy was associated with
individual traits in subsequent analyses (Appleby 1983;
Haley et al. 1994). However, individual-specific covariates
(in this case, male traits) can be incorporated directly into
a single structured model of B–T form, thereby circumventing
the problem of having to derive a linear hierarchy
first (Tufto et al. 1998; Firth 2005).We provide a case study
for the application of the structured B–T model for paired
comparisons and discuss its utility and the utility of tournament
designs for experimental studies of male contests
larger sample sizes and, consequently, greater statistical
power, as each individual is used more than once. Tournament
designs, however, are not widely used because such
a design results in males having different agonistic experiences
and the effects of unmeasured differences in fighting
ability and ‘experience effects’ can be difficult to
disentangle. That is, a winner may keep winning because
he has a series of attributes that make him a better fighter
or because of a self-reinforcing ‘winner effect’ and vice
versa for losers.We show how this problem can be circumvented
through use of a generalized Bradley–Terry model.
Traditionally, the B–T model has been used to assign
ranks to individuals within a linear hierarchy based on
paired observations. The only two previous applications of
the B–T model to animal dominance or aggression used
the model to estimate a complete hierarchy, then tested
whether position in the hierarchy was associated with
individual traits in subsequent analyses (Appleby 1983;
Haley et al. 1994). However, individual-specific covariates
(in this case, male traits) can be incorporated directly into
a single structured model of B–T form, thereby circumventing
the problem of having to derive a linear hierarchy
first (Tufto et al. 1998; Firth 2005).We provide a case study
for the application of the structured B–T model for paired
comparisons and discuss its utility and the utility of tournament
designs for experimental studies of male contests
การแปล กรุณารอสักครู่..