A ______ sample is a sample in which each member of the population has a known, nonzero, chance of being selected for the sample.
Deanna has been hired to visit the local shopping mall to conduct a survey about the upcoming political election. She needs to select respondents at the mall and ask them questions about their voting tendencies. Deanna decides to walk around the mall and select shoppers to participate. Which of the following sampling techniques best describes Deanna's method?
The average weight of the entire batch of the boxes of cereal filled today was 20.15 ounces. A random sample of four boxes was selected with the following weights: 20.05, 20.56, 20.72, and 20.43. The sampling error for this sample is _______.