Experiment Design

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

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

To investigate whether standing up while studying affects performance in an algebra class, a teacher assigns half of the 30 students in his class to stand up while studying and assigns the other half to not stand up while studying. Which of the following best describes this plan?

• This is an observational study

• This is an experiment

• This is a stratified random sample

• This is a cluster sample

A ​ (a)   should include

the following:

a. ​ (b)   of at least two treatment

groups, one of which could be a

control group.

b. ​ (c)   assignment/allocation of

treatments to experimental units.

c. ​ (d)   (more than one experimental

unit in each treatment group).

d. ​ (e)   of potential confounding variables

where appropriate

• well-designed experiment

• Comparisons

• Random

• Replication

• Control

treatment is imposed upon a subject and a response is recorded

• observational study

• experiment

• treatment

What type of study is described? A gym tries out a new weightlifting method to see if it will build muscle for their customers faster than their current method.

• Sample Survey

• Experiment

• Observational Study

Does listening to classical music while studying increase test scores?

• Survey

• Observational study

• Experimental study

Which of the following is a key distinction between well designed experiments and observational studies?

• More subjects are available for experiments than for observational studies.

• Ethical constraints prevent large-scale observational studies.

• Experiments are less costly to conduct than observational studies.

• An experiment can show a direct cause-and-effect relationship, whereas an observational study cannot.

• Tests of significance cannot be used on data collected from an observational study.