Identify the flaw in the argument: “We conducted a poll of 20 thirteen-year-old American boys, all of whom go to Central Middle School. 70% of them agreed that 7th grade English teacher, Mrs. Yoshihito-Simons, absolutely blows. The people have spoken! Most Americans clearly dislike Lauren Yoshihito-Simons.”
Answer
This is a sampling flaw. Luckily for all of us, the American people are not all thirteen-year-old boys at Central Middle School. Remember, polls need to be both large (which, for the LSAT, usually means at least 100 subjects) and representative. If you want to make a conclusion about the American people in general, you need to use a representative sample of those people.