  Spherical data is distributed on the sphere. The data appears in various
fields such as meteorology, biology, and natural language processing. However,
a method for analysis of spherical data does not develop enough yet. One of the
important issues is an estimation of the number of clusters in spherical data.
To address the issue, I propose a new method called the Spherical X-means
(SX-means) that can estimate the number of clusters on d-dimensional sphere.
The SX-means is the model-based method assuming that the data is generated from
a mixture of von Mises-Fisher distributions. The present paper explains the
proposed method and shows its performance of estimation of the number of
clusters.
