1. Which of the following are experiments?

2. Which of the following are experiment?

3. To test the effectiveness of a new drug for high blood pressure, Pharmaco recruits 200 subjects with high blood pressure by placing ads in the Daily Texan and the Austin American Statesman. The blood pressure of all 200 subjects is measured at the beginning of the experiment. On hundred of these individuals are randomly chosen to receive the new drug for six weeks, while the remaining one hundred patients receive a placebo. (Use of this drug is thus a variable with two states: new drug or placebo.) At the end of six weeks, Pharmaco measures the blood pressure of all 200 subjects, and discovers that those who received the new drug had lower blood pressure than those who received the placebo. Which of the following statements correctly describe the results of this experiment:

4. The Secrets of the Psychics video opened with an experiment in which a written horoscope (astrology prediction) was given to a college class to assess its (apparent) accuracy. The experiment involved a few simple manipulations that were shown on the tape.

Which of the following features of ideal data were present (at one or more levels) in this example?

5. A demonstration done in lecture involved putting vinegar and baking soda together and observing the outcome. In the same lecture, we gave the following five definitions useful for distinguishing between experiments and observations. Which of these definitions of an experiment does the vinegar and baking soda demonstration satisfy?

6. An experiment done to evaluate three drugs (AZT, ddi, and ddc) as potential treatments for AIDS considered four groups of patients, with the following results:

AZT alone 10% dead in about 3 years

ddi alone 5% dead in about 3 years

AZT and ddi 5% dead in about 3 years

AZT and ddc 5% dead in about 3 years

Which of the following conclusions can be drawn from these results?

7. Which of the following features of ideal data, when properly applied, helps ensure that an experimental manipulation will break as many unwanted correlations as possible? Mark exactly one answer.

Table of contents

Chapter 18. Experiments make the best controls