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:

• a convenience sample

• an oberservational study

• an experiment, but not double-blind

• a double-blind 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

• 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

We wish to investigate the relationship between the number seeds planted in a garden and the number of fruit grown. The explanatory variable (EV) is

• The number of fruit grown

• The amount of soil in the garden

• The number of hours spent watering the plants

• The number of seeds planted

An ​ (a)   does not have treatments imposed.

An ​ (b)   has treatments imposed.

• Observational Study

• Experiment

We wish to investigate whether a person’s age can be predicted from their IQ score. Which is the explanatory variable (EV)?

• Age

• IQ Score

• Both Age and IQ Score

• None of the Above

This deliberately imposes some treatment on individuals to measure their responses.

• explanatory variable

• response variable

• factor

• experiment

We wish to investigate the relationship between the time spent shopping and the number of items bought. The response variable (RV) is

• The number of items bought

• The number of items at the shop

• The time spent shopping

• The time spent getting to the shops

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

Four groups of randomly selected people are assigned a different diet. After six months, the blood pressures of each group are compared.

• Observational Study

• Experiment