Observational Studies and Designed Experiments

What was the goal of the first study mentioned in the text?

• To determine if radio frequencies from cell phones increased brain tumors

• To investigate cancer risk among Danish cell phone users

• To examine whether chronic exposure to RF radiation caused brain tumors in rats

• To compare the rate of brain tumors in cell phone users to the general population

What type of study was the first study?

• Observational study

• Designed experiment

• Both observational study and designed experiment

• Neither observational study nor designed experiment

What was the goal of the second study mentioned in the text?

• To determine if radio frequencies from cell phones increased brain tumors

• To investigate cancer risk among Danish cell phone users

• To examine whether chronic exposure to RF radiation caused brain tumors in rats

• To compare the rate of brain tumors in cell phone users to the general population

What type of study was the second study?

• Observational study

• Designed experiment

• Both observational study and designed experiment

• Neither observational study nor designed experiment

What is the explanatory variable in both studies?

• The level of cell phone usage

• The rate of brain tumors

• The type of RF radiation

• The number of rats in each group

What is the response variable in both studies?

• The level of cell phone usage

• The rate of brain tumors

• The type of RF radiation

• The number of rats in each group

What is an observational study?

• A study where the researcher observes the behavior of individuals without trying to influence the outcome

• A study where the researcher assigns individuals to different groups and changes the value of the explanatory variable

• A study where the researcher observes the behavior of individuals and tries to influence the outcome

• A study where the researcher assigns individuals to different groups without changing the value of the explanatory variable

What is a designed experiment?

• A study where the researcher observes the behavior of individuals without trying to influence the outcome

• A study where the researcher assigns individuals to different groups and changes the value of the explanatory variable

• A study where the researcher observes the behavior of individuals and tries to influence the outcome

• A study where the researcher assigns individuals to different groups without changing the value of the explanatory variable

What is confounding in a study?

• When the effects of two or more explanatory variables are not separated

• When the researcher observes the behavior of individuals without trying to influence the outcome

• When the researcher assigns individuals to different groups and changes the value of the explanatory variable

• When the researcher assigns individuals to different groups without changing the value of the explanatory variable

What can observational studies conclude?

• Causation

• Association

• Both causation and association

• Neither causation nor association