Several statistical applications demand the adoption of models in whic
h the response is binary but the outcomes of different trials exhibit
some degree of correlation. Although the independent case is well know
n and treated even in elementary textbooks, results on correlated Bern
oulli trials are hardly found in the literature. Analogues of the bino
mial and negative binomial distributions are presented in this article
when the correlation is of the Markovian type. Probability-generating
function, probability mass function, mean, and variance are derived.
The analysis allows illustration of a variety of techniques useful in
the study of discrete distributions appropriate for second-level proba
bility courses. An example on customer brand switching discussed by Ol
kin, Glesser, and Derman is presented as illustration.