In each of the following situations, data are obtained by conducting a research study. Classify each research study as Experimental or Correlational.

A student is interested in how well majors in the social sciences do monetarily in the real world. She collects data from a sample of college graduates who majored in the social sciences, recording their specific majors, their current jobs, and their salaries for the previous year.

A psychologist is interested in gender and cognition. She collects data on a large sample of siblings, recording their gender, birth order, and IQ.

An economist is interested in the demand behavior of rats. Rats in a rat lab have two levers in their cages. Pressing one lever dispenses Tom Collins mix (without alcohol); pressing the other lever dispenses the same amount of a sodium saccharin solution. Psychologists obtain data on the demand behavior by altering the total number of presses the rats are allotted and the number of presses required to dispense each of the fluids.

You want to find out whether caffeine mitigates the effect of alcohol on reaction time.

Speed is measured in miles per hour above or below the 60-mph speed limit, with 1 mph being the smallest unit on the scale.

Suppose the first subject scores 9 mph. Determine the real limits of 9.

The lower real limit is:__

The upper real limit is:___

When measuring weight on a scale that is accurate to the nearest 0.1 kilogram, what are the real limits for the weight of 56 kilograms?

___

When measuring weight on a scale that is accurate to the nearest 0.2 kilogram, what are the real limits for the weight of 95 kilograms?

_____