Efficient Data Formats

Hi,

I was wondering if someone could please direct me on how to choose the
best format in order to save, open, and use data.  I am currently
using datasets that are in csv format.  However, they are purely
numeric and I think I should be to reduce their size substantially.

Thank you for your time,

Francis Smart
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PhD Student - Michigan State University
Agricultural, Food, and Resource Economics
(406) 223-8108