Scientific Method Practice Your Name
A researcher from Lipton wants to determine if increased rates of urination after tea drinking results from the presence of caffeine in the tea or from other substances released when tea is brewed. She performs the following study in which four groups of five individuals each are given the following drinks in the same amounts. Individuals are randomly assigned to groups. The amount of urine produced by each member of each group is given. In group 1, the drink has the same amount of caffeine as regular tea. In group 3, the caffeine has been chemically removed from normal tea.
Group 1 Group 2 Group 3 Group 4
hot water + caffeine hot water hot decaffeinated tea hot tea (w/caffeine)
12 6 5 14
13 4 4 12
12 7 7 13
14 6 5 14
13 5 6 11
Avg. 12.8 5.6 5.4 12.8
1. What is the purpose of Group 2?
a. It was not necessary and does not help interpretation of this experiment.
b. Along with Group 4 it tests the hypothesis that caffeine causes increased urine production.
c. Along with Group 1 it tests the hypothesis that caffeine causes increased urine production.
d. To measure urine production in individuals who don't like tea.
2. What is the purpose of Group 3?
a. It was not necessary and does not help interpretation of this experiment.
b. Along with Group 2 it tests the hypothesis that caffeine causes increased urine production.
c. Along with Group 1 it tests the hypothesis that caffeine causes increased urine production.
d. Along with group 2 it tests the hypothesis that increased urination in tea drinkers is caused by substances in tea other than caffeine.
3. The independent variables tested by the above groups are....?
a. temperature, caffeine, and urine production
b. urine production, caffeine, and "other substances in tea"
c. "other substances in tea", caffeine, and temperature
d. urine production and caffeine only
e. caffeine, and "other substances in tea" only
4. The dependent variable(s) in the above experiment is/are....?
a. temperature
b. caffeine
c. "other substances in tea"
d. all of the above
e. none of the above
5. Which of the following hypotheses is best supported by the data?
a. Decaffeination of tea increases urine production.
b. Increased urination in tea drinkers is related to the temperature of the liquid consumed.
c. Increased urine production in tea drinkers is caused by caffeine.
d. Increased urination in tea drinkers is caused by substances in tea other than caffeine.
e. none of the above are supported
6. Which of the hypotheses in question #5 is not tested in the above experiment?
7. Can you do controlled tests of the effects of caffeine and the effects of the other ingredients in
tea (other than caffeine)? If so, what will the control be for each test? What are some other
variables which should be held constant for each test?
8. Briefly describe an experiment to test the hypothesis you indicated in question #6. Be sure to include your predicted results.