Problem
Someone has a three year old son, who loves to eat. His favorite foods are edamame and fish (he's mostly pescatarian in his diet, his father and I are both vegan). This kid can eat. He eats all day, grazes, eats full meals.
Last week he spent a few hours at his cousin's house, and had chicken and pasta. A lot of chicken and pasta.
That night he was up all night, throwing up.
Can we explore the idea of internal and external validities with this situation? How would we apply any and all concepts?