Statistical Experiments

An ​ (a)   does not have treatments imposed.

An ​ (b)   has treatments imposed.

• Observational Study

• Experiment

A market research company wishes to find out whether the population of students at a university prefers Starbucks or Dunkin Donuts. A random sample of students is selected, and each student is asked first to try both but the order they try them is randomly decided with a coin toss (heads: Starbucks, then Dunkin. tails: vice versa). They then indicate which brand they prefer. This is an example of

• completely randomized experiment

• an observational study

• a blocked experiment

• matched pairs experiment

In order to perform an experiment using 60 members of a gym, I first divide the list of members into men and women because I feel that the results will be different based on gender. I then randomly choose 30 men and 30 women. I assign half of the men to the treatment group and half to the control group. I repeat this procedure with the women. This is an example of a:

• completely randomized experiment

• blocked experiment

• matched pairs experiment

• observational study

Participants are assigned to groups, based on gender. Then, within each group, participants are randomly assigned to treatments. For this design, 250 men get the placebo, 250 men get the vaccine, 250 women get the placebo, and 250 women get the vaccine. What type of experiment design is this?

• Completely Randomized Experiment

• Matched Pairs Experiment

• Blocked Experiment

Researchers want to know how diet influences a child's brain development. In a sample of 100 5 year old children, 20 of the children are given a vegan diet, 20 are given a pescatarian diet, 20 are given a standard American diet, and 20 are given a paleo diet. This is an example of...

• a matched pair, with pairs determined by diet type

• a block design, with blocks determined by age.

• a block design, with blocks determined by diet type.

• a completely randomized experiment

Left-handedness is the preference for the left hand over the right for everyday activities such as writing. Studies indicate that about 93% of the population may be characterized as right-handed. Researchers would like to conduct a study to determine if left-handed teens differ significantly in their ability to memorize facts than right-handed teens.

The explanatory variable in this study is:

• ability to memorize facts.

• age.

• handedness.

• researchers.

• none of the above.

Researchers were interested to know whether internal vehicle temperatures vary by outside temperatures. To evaluate this, temperature rise was measured continuously over a 60-minute period in a dark SUV on 16 different clear, sunny days with outside temperatures ranging from 72^oF to 96^oF.

What type of study is this?

• a census.

• a survey.

• an observational study

• an experiment

A custodian notices some dirty tables and wants to know which cleaner is more effective. He tests three different cleaners and looks at how well they clean compared to tap water. What is the explanatory variable?

• type of cleaner

• tap water

Mrs. Barton wanted to see how different types of music affected students' pulse rates. She played different types of music: heavy metal, rap, R&B, alternative, pop, country, and classical music. Identify the response variable. 

• pulse rate
• types of music
• classical music resulted in the highest pulse rate
• Mrs. Barton

A student is planning an experiment to find out how the height from which he drops a ball affects how high the ball bounces. The response variable is the _____.

• Diameter of the ball
• Force acting on the ball
• Height that the ball bounces
• Height from which the ball is dropped