You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Human_Development_Index

Context:
The formula defining the HDI is promulgated by the United Nations Development Programme (UNDP). In general, to transform a raw variable, say , into a unit-free index between 0 and 1 (which allows different indices to be added together), the following formula is used:

Question:
What entity makes the defining formula for the HDI well-known?

the United Nations Development Programme