Principles of Experimental Design

A study compares the effect on college students of two different TV advertisements for spring break in Gulf Shores, Alabama. Call the ads "Ad #1" and "Ad #2". We want to know which ad makes more students want to visit Gulf Shores during spring break. The subjects are 90 students taking a course in hotel management. The design of the study looks like the picture above. What is the statistical name for this study design?

• Observational study

• simple random sample.

• randomized comparative experiment.

• matched-pairs experiment.

A study compares the effect on college students of two different TV advertisements for spring break in Gulf Shores, Alabama. Call the ads "Ad #1" and "Ad #2". We want to know which ad makes more students want to visit Gulf Shores during spring break. The subjects are 90 students taking a course in hotel management. The design of the study looks like the picture above. 
The method used to form the groups appears in the diagram at the point marked "Question A". This method is...

• Men in Group 1, Women in Group 2

• Students chose which group they want. 

• Voluntary assignment 

• Random assignment. 

A study compares the effect on college students of two different TV advertisements for spring break in Gulf Shores, Alabama. Call the ads "Ad #1" and "Ad #2". We want to know which ad makes more students want to visit Gulf Shores during spring break. The subjects are 90 students taking a course in hotel management. The design of the study looks like the picture above. 
What is Group 2's treatment (at the point marked "Question B)?

• a placebo

• Ad #2

• One of the ads, chosen at random.

• Watch TV but see no advertisement

Which is important in designing a good experiment?
1. Randomization in assigning subjects to treatments
2. Control of potentially confounding variablese
3. Replication of the experiment on a sufficient number of subjects

• 1 and 2
• 1 and 3
• 2 and 3
• All 3

Students used various temperatures of water to see which one dissolved candy faster.

What was the explanatory variable?

• Amount of Candy

• Amount of Water

• Temperature of Water

• Time for Candy to Dissolve

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

• observational study

• stratified sample

• matched pairs experiment

Identify the design  for the experiment

• completely randomized, the factor is pesticide

• randomized block, blocked on tree type, the factor is pesticide

• This experiment is single blind, blocked by pesticide

• The experiment is double blind, the factors are tree type and pesticide

Can pleasant aromas help a student learn better? Two researchers believed that the presence of a floral scent could improve a person's learning ability in certain situations. They had 22 people work through a pencil-and-paper maze 6 times. Three of the times they wore a floral-scented mask and three times they wore an unscented mask. The three trials for each mask followed one another. Testers measures the length of time it took subjects to complete each of the six trials. They reported that, on average, subjects wearing the floral-scented mask completed the maze more quickly that those wearing the unscented mask, although, the difference was not statistically significant. This study is:

• convenience sample

• an oberservational study

• an experiment, but not double-blind

• a double-blind 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:

• randomized comparative design

• blocking design

• matched pairs design

• double blind simple random sample

Any individual associated with an experiment who is not aware of how subjects have been allocated to treatment groups

• statistically significant

• blocking

• matching

• blinding