According to a report published in 2014, about 43% of all Jews reside in Israel (6.1 million), and 40% in the United States (5.7 million), with most of the remainder living in Europe (1.4 million) and Canada (0.4 million). These numbers include all those who self-identified as Jews in a socio-demographic study or were identified as such by a respondent in the same household. The exact world Jewish population, however, is difficult to measure. In addition to <answer>issues with census methodology</answer>, disputes among proponents of halakhic, secular, political, and ancestral identification factors regarding who is a Jew may affect the figure considerably depending on the source.
What is one reason the world population of Jews difficult to determine?
issues with census methodology