Story point is a arbitrary relative measure used by Scrum teams to define the effort required to implement one story. In this article, Mahfoud Amiour proposes an approach to measure the cost of story points implementation.
Mahfoud Amiour has defined from his experience as an Agile consultant a metric to measure the cost related to the implementation of story points. This metric is called SPOC (Story POint Cost). It should allow to track development costs and also make the Scrum team aware about the budget issues of their project.
The article provides a step-by-step process to compute the metric at sprint and release level. It also contains a a case study that illustrates the usage of the SPOC metric with one of his clients. In this case study, the author explain how to analyze the metric and proposes some corrective actions to improve it. One of the most interesting part of this article is also the discussion about Scrum and metrics that it initiated.
Read the complete article on https://www.scrumalliance.org/community/articles/2015/march/spoc-story-point-cost