The Consumer Product Testing Laboratory selects a dozen batteries (labeled 9 volts) from each company that makes them. Each battery is tested for its actual voltage level.
a. Are the values obtained discrete or continuous?
b. Identify the level of measurement (nominal, ordinal, interval, ratio) for the voltages.
c. Which type of sampling (random, stratified, systematic, cluster, convenience) is being used?
d. Is this an observational study or an experiment?
e. What is an important effect of consumers using batteries that are labeled 9 volts when, in reality, the voltage level is very different?