Table 1.

Comparison of characteristics of different types of food outlets.

Type of food outlets	Type of food provided	Who cooked the food?	How to know what kind of food they had in a meal	Cost of collecting the longitudinal data
Online restaurants	Cooked	Chefs in the restaurants	Online purchasing record	Low
Offline restaurants	Cooked	Chefs in the restaurants	Survey	High
Online markets	Fresh or preprocessed	Consumers themselves or their family members	Survey	High
Offline markets	Fresh or preprocessed	Consumers themselves or their family members	Survey	High