In a correlational study the researcher measures variables, often in some natural setting, to see whether they are related to one another. The closer a correlation coefficient is to 0, the weaker the relationship between two variables. The correlation between stress and illness is around .3. The correlation between people's measured attitudes and their behavior is on average around .4. Random assignment means that any participant has an equal chance of being assigned to either of the two conditions before the experiment is conducted.
Experiments allow researchers to make cause-effect conclusions.
Random assignment is what permits cause-effect conclusions in experiments. The nerve impulse is electrical 1. Analogy to the digital codes of computers. The synapse 1. Recording from two ears at once.