Sampling and Experiments

Taking a SRS from three homogenous groups

• Stratified
• Cluster
• Multistage
• Systematic

Taking a SRS of three diverse groups

• Stratified
• Cluster
• Multistage
• Systematic

Undercoverage in a survey produces 

• sampling variation
• errors in the results
• bias
• systemic variation

A random sampling method is generally

• consistent
• unbiased
• accurate
• simple

Which method is best?

• SRS
• cluster
• stratified
• it depends on the context

Random assignment of treatments reduces

• bias
• variation
• undercoverage
• placebo effect

Sources of variation in an experiment that are planned.

• extraneous variables
• factors
• treatments
• blinding

Using a placebo helps reduce

• variation
• blinding
• double-blinding
• bias

You should block by gender if you suspect the response to treatments

• is different between subjects
• is the same in both genders
• is high in each gender 
• is very different between genders

An observational study can NOT suggest

• cause and effect
• a significant relationship
• two variables are independent
• two variables are associated