The abnormal activity of which transmitter is linked to depression and panic disorder?

Two sets of observations assessing shoe size and IQ are compared. Which of the following is the most likely outcome?

a. The two variables will be both positively and negatively correlated. b. The two variables will be uncorrelated. c. The two variables will be negatively correlated. d. The two variables will be positively correlated.

Stratified random sampling that tries to ensure an equal number of units per group is also called ____ random sampling

a. modal b. disproportionate c. independent d. proportional