This term adds one network statistic to the model equaling the sum over the actors of each actor's indegree taken to the 3/2 power (or, equivalently, multiplied by its square root). This term is analogous to the term of Snijders et al. (2010), equation (12). This term can only be used with directed networks.
# binary: idegree1.5ergmTerm for index of model terms currently visible to the package.
ergm:::.formatTermKeywords("ergmTerm", "idegree1.5", "subsection")