Which of the following is or are important in designing an experiment?

I. Control of all lurking variables in the experiment.

II. Randomization of subjects to treatment groups.

III. A large number of subjects to control for small-sample variability

A botanist wants to test how much sunflowers in three different temperature environments - 15°C, 20°C, and 25°C - respirate (oxygen) in mol/L during germination. 300 sunflowers seeds were each given an equal volume of water (150 mL) each week, each separated randomly into three identical greenhouses. The results were collected. Which of the following is TRUE?

John Adams, a history teacher, wanted to determine whether short answer or multiple choice were more effective in testing his 86 students’ recall of over six periods to select from. The students in his first period were given either the short-answer (S) or the multiple choice (M) treatment, via coin flip, into two equally-sized groups. After that, the students may begin their tests. Both treatments contain 20 similar recall questions. This experiment is NOT ideal because John Adams

The U.S. Bureau of Labor Statistics collects sample data from households. In the Consumer Expenditure Survey, approximately 500,000 households have been randomly selected to partake in the survey. 300,000 households responded; only 200,000 returned their results, where 20 strata are separated based on income. What is the sample size of the Consumer Expenditure Survey?

Data were randomly collected in 20 cities on the percentage of women in the workforce in 1990 and in 1994. A two-proportion z-test is performed to determine if there is ongoing discrimination. What kind of design was this?

I. A prospective observational study.

II. A cluster sample survey.

III. A retrospective observational study.

Algebra teacher Euler Leonard asked the first 15 students to enter his first period class the amount of time they spend doing their homework using technology. What is a large problem associated with this survey?

Which of the following survey demonstrates response bias?

The web portal AOL places opinion poll questions next to many of its news stories. Simply click your response to join the sample. One of the questions in January 2008 was "Do you plan to diet this year?" More than 30,000 people responded, with 68% saying "Yes." You conclude that

A farmer is conducting an experiment to determine which variety of apple tree, Fuji or Gala, will produce more fruit in his orchard. The orchard is divided into 20 equally sized square plots. He has 10 trees of each variety and randomly assigns each tree to a separate plot in the orchard. What are the experimental unit(s) in the study?

To gather information about the validity of a new standardized test for 10^th grade students in a particular state, a random sample of 15 high schools was selected from the state. The new test was administered to every 10^th grade student in the selected high schools. What kind of sample is this?