I plan to perform a meta-analysis for which I will need to contact some authors (not professors) because their articles do not mention the outcomes relevant to my study, although they most probably have measured them.
I am very new to this field and I would like to know which way of contacting them I should privilege, to ensure the best chances that they will share the relevant data with me. Is a simple, polite message sent by mail enough or are there other tips that would help me achieve this goal? Are there namely other ways than an email?
I am not asking for general advice about how to address an academic. Rather, I'd like to know if there are some specific tips that could be useful in the particular situation when you want to get data from an author. For example, if the author has a Researchgate account, is it better (in terms of answer chances) to use RG messaging system, or to send a mail ?