COM 304 FINAL REVIEW QUESTIONS & VERIFIED
ANSWERS
What is the purpose of conducting experimental studies of communication? - Answers -
Experimental studies can be replicated One can do them again and find the same or
similar results. Able to be repeated. Falsifiability - ability to be proven wrong.
What are three features of a "true" experiment? - Answers - Researcher manipulates
the independent variable
Researcher randomly assigns participants to conditions
Researcher controls extraneous variables
What are experimental (treatment) and control conditions? - Answers - Treatment
condition is the IV, what is being tested. The control condition is the DV, what stays
consistent.
What does it mean to "manipulate" an independent variable (vs. an attribute variable)? -
Answers - • Manipulating the IV means that the researcher develops different levels of
the IV, determines which participants are exposed to each level
• An attribute variable is a pre-existing condition of participants, can't be manipulated by
the researcher (sex, race, age, verbal aggressiveness, etc.)
What is random assignment, and how does it differ from random selection? - Answers -
Random selection refers to how sample members (study participants) are selected from
the population for inclusion in the study. Random assignment is an aspect of
experimental designin which study participants are assigned to the treatment or control
group using a random procedure.
Random selection requires the use of some form of random sampling (such as stratified
random sampling, in which the population is sorted into groups from which sample
members are chosen randomly). Random sampling is a probability sampling method,
meaning that it relies on the laws of probability to select a sample that can be used to
make inference to the population; this is the basis of statistical tests of significance.
Random assignment takes place following the selection of participants for the study. In
a true experiment, all study participants are randomly assigned either to receive the
treatment (also known as the stimulus or intervention) or to act as a control in the study
(meaning they do not receive the treatment).
, Why is random assignment important? - Answers - Participants must show no biases.
Randomization is important so there are not multiple independent or extraneous
variables outside of your control.
What are extraneous variables? - Answers - Extraneous Variables are undesirable
variables that influence the relationship between the variables that an experimenter is
examining. Another way to think of this, is that these are variables the influence the
outcome of an experiment, though they are not the variables that are actually of interest.
How can extraneous variables be controlled. - Answers - Decrease the influence of
these variables by having a controlled study. falsifiable experiment. Make sure that it is
the manipulation of the IV that has influenced the DV. Take other variables into
consideration when doing study. All variables should be mutually exclusive and defined.
Exhaustive - every unit and observation falls into a category.
Be able to distinguish between an experiment vs. other types of research (e.g., a survey
where no inference can be made about cause and effect). - Answers - Experiment vs.
survey. Experiment is falsifiable, makes predictions, able to be repeated, shows caused
and effect. Experiments can be refuted and reproduce.
Be able to recognize notation (e.g., for a two-group post-test only experimental design).
(see experimental design slides) - Answers - • Rows = Group 1 (treatment = EPH) and
group 2 (control = SR)
• R = random assignment to experimental condition (coin flip)
• X = "treatment" (phrase EPH; absent from control condition)
• O = observe (measure) the dependent variable (giving) (called "post-test" because
done after the treatment)
2. Claims about Causality:
• What are 3 criteria for making causal claims? - Answers - 1- Temporal precedence
(prove that cause happened before the effect)
2- Covariation of the cause and effect - Before you can show that you have a causal
relationship you have to show that you have some type of relationship.
3- No plausible alternatives
Why doesn't correlation = causality? What is a spurious relationship? - Answers - Many
things can be correlated with no real relationship. Example: amount of ice cream eaten
in 2014 vs. amounts of murder. Just because they both increased does not mean they
are correlated. A spurious relationship is one
In statistics, a spurious relationship (see also spurious correlation and spurious
regression) is a mathematical relationship in which two or more events or variables are
not causally related to each other (i.e. they are independent), yet it may be wrongly
inferred that they are, due to either coincidence or the presence of a certain third,
unseen factor (referred to as a "common response variable", "confounding factor", or
"lurking variable").
ANSWERS
What is the purpose of conducting experimental studies of communication? - Answers -
Experimental studies can be replicated One can do them again and find the same or
similar results. Able to be repeated. Falsifiability - ability to be proven wrong.
What are three features of a "true" experiment? - Answers - Researcher manipulates
the independent variable
Researcher randomly assigns participants to conditions
Researcher controls extraneous variables
What are experimental (treatment) and control conditions? - Answers - Treatment
condition is the IV, what is being tested. The control condition is the DV, what stays
consistent.
What does it mean to "manipulate" an independent variable (vs. an attribute variable)? -
Answers - • Manipulating the IV means that the researcher develops different levels of
the IV, determines which participants are exposed to each level
• An attribute variable is a pre-existing condition of participants, can't be manipulated by
the researcher (sex, race, age, verbal aggressiveness, etc.)
What is random assignment, and how does it differ from random selection? - Answers -
Random selection refers to how sample members (study participants) are selected from
the population for inclusion in the study. Random assignment is an aspect of
experimental designin which study participants are assigned to the treatment or control
group using a random procedure.
Random selection requires the use of some form of random sampling (such as stratified
random sampling, in which the population is sorted into groups from which sample
members are chosen randomly). Random sampling is a probability sampling method,
meaning that it relies on the laws of probability to select a sample that can be used to
make inference to the population; this is the basis of statistical tests of significance.
Random assignment takes place following the selection of participants for the study. In
a true experiment, all study participants are randomly assigned either to receive the
treatment (also known as the stimulus or intervention) or to act as a control in the study
(meaning they do not receive the treatment).
, Why is random assignment important? - Answers - Participants must show no biases.
Randomization is important so there are not multiple independent or extraneous
variables outside of your control.
What are extraneous variables? - Answers - Extraneous Variables are undesirable
variables that influence the relationship between the variables that an experimenter is
examining. Another way to think of this, is that these are variables the influence the
outcome of an experiment, though they are not the variables that are actually of interest.
How can extraneous variables be controlled. - Answers - Decrease the influence of
these variables by having a controlled study. falsifiable experiment. Make sure that it is
the manipulation of the IV that has influenced the DV. Take other variables into
consideration when doing study. All variables should be mutually exclusive and defined.
Exhaustive - every unit and observation falls into a category.
Be able to distinguish between an experiment vs. other types of research (e.g., a survey
where no inference can be made about cause and effect). - Answers - Experiment vs.
survey. Experiment is falsifiable, makes predictions, able to be repeated, shows caused
and effect. Experiments can be refuted and reproduce.
Be able to recognize notation (e.g., for a two-group post-test only experimental design).
(see experimental design slides) - Answers - • Rows = Group 1 (treatment = EPH) and
group 2 (control = SR)
• R = random assignment to experimental condition (coin flip)
• X = "treatment" (phrase EPH; absent from control condition)
• O = observe (measure) the dependent variable (giving) (called "post-test" because
done after the treatment)
2. Claims about Causality:
• What are 3 criteria for making causal claims? - Answers - 1- Temporal precedence
(prove that cause happened before the effect)
2- Covariation of the cause and effect - Before you can show that you have a causal
relationship you have to show that you have some type of relationship.
3- No plausible alternatives
Why doesn't correlation = causality? What is a spurious relationship? - Answers - Many
things can be correlated with no real relationship. Example: amount of ice cream eaten
in 2014 vs. amounts of murder. Just because they both increased does not mean they
are correlated. A spurious relationship is one
In statistics, a spurious relationship (see also spurious correlation and spurious
regression) is a mathematical relationship in which two or more events or variables are
not causally related to each other (i.e. they are independent), yet it may be wrongly
inferred that they are, due to either coincidence or the presence of a certain third,
unseen factor (referred to as a "common response variable", "confounding factor", or
"lurking variable").
