Field Research is also called investigation from primary sources. That is, we conduct research that has never been done before; it's original. Books, magazines, internet sources, are all secondary sources: we read ideas and information that someone else has researched for us.
Field research is a powerful tool if it is done well. Whatever happens, all research should be reliable and valid.
Reliability -- Is the research repeatable? Would it achieve the same results?
Validity -- Does the research really measure what you say it does?