1.4 Experimental Design and Ethics

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

Steve wanted to see if different types of fertilizer influence sunflower growth. What is the explanatory variable?

• type of fertilizer

• sunflower grown without fertilizer

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

What is the purpose of a control group in an experiment?

• To provide a standard for comparison

• To introduce new variables

• To ensure the experiment is biased

• To change the outcome of the experiment

In a study to determine the effect of sleep on cognitive performance, participants are randomly assigned to sleep for 4, 6, or 8 hours before taking a cognitive test. What is the response variable?

• Cognitive test score

• Participant's age

• Number of hours slept

• Type of cognitive test

A researcher wants to know if the type of lighting affects plant growth. She uses LED, fluorescent, and natural sunlight to grow plants. What is the explanatory variable?

• Type of lighting

• Plant growth

• Amount of water given

• Type of plant

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