Does a US-based author have a better chance of publishing in JMD?
Not directly. In fact a plurality of JMD papers comes from the international community. Indirectly, however, authors familiar and competent in the prevailing scholarly standards will have a much higher chance of publishing at JMD. Studying and referencing previous articles from JMD is very helpful in this respect. For more discussion on this topic see the JMD September 2008 Editorial: Globalization and Internationalism.
