In correlational observations it is sometimes difficult to know ...

[jerry coleman]

In correlational observations it is sometimes difficult to know which variable might have caused any change in the other variable. This is sometimes called the ___________________ _ problem
 
  Fill in the blank(s) with correct word

Question 2

Studying a detailed account of the events of a single person's life is called a(n) ___________________ _.
 
  Fill in the blank(s) with correct word

[izzat]

Answer to Question 1

directionality

Answer to Question 2

case history

[jerry coleman]

Thanks for the timely response, appreciate it

[brbarasa]

Gracias!