Sampling and observational studies

Correlation and Causality

e.g. Passage:

-Eating breakfast may beat teen obesity;

-Regular breakfast eaters seemed more physically active than breakfast skippers;

-Regular breakfast eaters tended to gain less weight and had a lower body mass index than breakfast skippers.

Conclusions:

-Eating breakfast--Not obese

-Eating breakfast--Active

-Skipping breakfast--Obese

**We need to consider what's the relationship between these behaviors and the consequences they lead to, so think about the following questions: 1.Does the conclusion really suggest that eating breakfast leads to activity? 2.Does the conclusion just suggest being more active may have things to do with eating breakfast?

Causality

A causes B/ B causes A

-Eating breakfast causes not obese

-Eating breakfast causes activity

-Skipping breakfast causes obesity

Correlation

Whenever B is happening, A might happen at the same time

-Breakfast eating correlates with obesity

-Breakfast eating correlates with activity

-Breakfast skipping correlates with obesity

*Those relationships are all mutual