1. Voluntary response samples often under represent people with strong opinions. 2. Convenience samples often lead to under coverage bias. 3. Questionnaires with non-neutral wording are likely to have response bias. 4. In an observational study we impose a treatment on the subjects. 5. The entire group of individuals we want information about is called the sample.

Bob: coke is baby pandas.jim: what? how do you figure that coke is baby pandas? bob: because this book says so.jim: how do we know the book is correct? bob: because it says that coke is baby pandas.jim: how does that prove the book's accuracy? bob: because it's statement involving coke and baby pandas is correct, therefore it is accurate.jim: how do we know that it's correct? bob: because we have concluded that the book is accurate, and therefore the statement is correct.therefore, coke is baby pandas.