Variables
The dependent variable is the same as the:
a. response variable
b. explanatory variable
Response Variable
You randomly assign 20 subjects to a control group and 20 subjects receive a new type of pain medication. You compare the groups to determine if the medication was effective in reducing pain. What type of experiment is this:
randomized comparative
blocked
matched pairs
Randomized Comparative Experiment
You wonder if amount of sleep affects academic performance. You ask your peers how much sleep they got the night before a test and what their test grade was. You graph the data to determine if there is a relationship. Is this an example of an experiment or observational study?
observational study
You give 3 groups of subjects different doses of a medication. One groups gets a placebo. How many levels does this experiment have?
Four
You do a correlational study to see if there is a relationship between amount of TV watched/day and overall GPA. What is the independent variable?
Amount of TV watchedd/day
You give your math class a test on new material before teaching it to them. After teaching them the new material, you re-test them to see how much they've learned. What type of experimental design is this?
Matched Pairs
You wonder if the amount of time spent in prison affects one's level of anxiety. You perform a study to investigate. Would this be an experiment or an observational study?
Observational study
You decide to test the effectiveness of a new sports drink on running performance. Explain what the placebo would be in this case.
The placebo would be a drink that smelled, looked and tasted like the sports drink.
You conduct an experiment to determine the effectiveness of a new type of laundry stain remover. You compare the amount of a stain it removes to the amount that the leading product on the market is able to remove. Identify the dependent and independent variables.
Dependent Variable: amount of stain it removes
Independent Variable: which type of stain remover was used
You recruit 50 men and 50 women to participate in your study. You randomly assign 25 men to a group that receives a placebo; the other 25 receive the treatment. You do the same with the women. What type of experimental design is this?
Blocked
You want to compare the effectiveness of two different types of fertilizers. You divide your lawn in half and use one type on one half, and the other type on the other half. Is this an observational study or an experiment?
Experiment
You compare the effectiveness of a new drug to an existing one on the market. The old drug is effective 80% of the time. In a sample of 100 subjects, the new drug is effective 81% of the time. Is this statistically significant? Explain.
This is not statistically significant because the difference is not large enough to conclude that it is not due to chance.
You conduct an experiment to find out if amount of sleep affects concentration ability. Identify the dependent and independent variables.
Independent variable: amount of sleep
Dependent variable: concentration ability
You conduct an experiment to explore the effect of taking vitamins on the health of teenage girls. You divide the subjects into two groups. You make sure that for every girl in the first group, there is a girl in the second group who is the same age and is in the same kind of overall health. What type of experimental design is this?
Matched Pairs
You decide to study the impact large schools have on the overall education of high school students. Would you do an observational study or experiment? Explain.
You would do an observational study because you could not randomly assign students to a type of school.
Give an example of an experiment that could be double-blind. Explain how it could be double-blind.
You do a study to determine the effect of advertising on popcorn sales in a movie theater. In one theater, the viewers are shown a short popcorn ad before the movie. In an adjacent theater, they are not shown the ad. Researchers record the number of people from each theater who get up and buy popcorn. Name a confounding variable.
Confounding variables:
temperature of movie theater (or anything else that could be a difference between the two theaters)
proximity to popcorn
You want to study the effect of exercise on anxiety. Explain how you could do a matched pairs experiment to do this.
Suppose you want to study the effect of Vitamin C in preventing the common cold. Explain how you could do this:
- by doing an observational study
- by doing an experiment
Give an example of a double-blind experiment that has 3 levels, including a placebo.