Subjects are the source of information in a food consumption study. What did they eat and when did they eat it. Do we have just recall data or did they keep track of what they were eating? Are we looking at short term intake, the last day, the last week, the last 3 days?

How many subjects are needed for a good study? What other information to we need to get from them? How many researchers are collecting the information? Are they all using the same techniques for identifying food?

There are many questions to be answered here and we will tackle them in the following posts.