Things to decide before collecting data:
define goal of study
define population
define sampling frame
define variables
define data collection methods
define measuring methods
define analysis methods
Collection Methods: scientific experiment, survey, ..
Say we want to do a survey to see whether people prefer Coke over Pepsi - how do we do it?
Example: risk of smoking
------ experiment on lab animals (rats, mice, monkeys,..)
------ survey of smokers / nonsmokers
Variables
------ what measures effect of smoking?
------ lung cancer deaths
------ other diseases
------ bad teeth
Population - Sampling Frame
sampling frame is a "listing" of all the elements of a population
example: 1948 presidential elections Harry S. Truman vs. Thomas E. Dewey
Discuss phone surveys (random dialing, bias, recalls etc.)
For more on data collection see page 20 of the textbook.