Experimental Research

The idea behind an experiment is to manipulate an ______ variable to examine whether it changes the _____ variable that we measure while controlling as many confounding variables as possible.

• independent; dependent

• dependent; independent

• dependent; control

• control; independent

Which are defining characteristics of experimental research?

• Manipulation of the independent variable

• Holding all extraneous variables in the research situation constant

• Ensuring that all subjects in the experimental and control conditions have equal personal characteristics and with respect to the dependent variable

• Manipulation of the dependent variable

What does "manipulation of the independent variable" mean?

• Researcher controls the level of the dependent variable to see what happens

• Researcher controls the independent variables to see how they affect the control

• Researcher controls the level of the independent variable that the subjects receive

There can be several independent variables in an experiment.

• True

• False

Answer explanation

There can only be ONE independent variable - this is what is actually being tested. If you change several things, you would not know which change actually caused the result. For example, if I give Max 3 new foods and he gets sick, I would not know which one caused the result (getting sick).

What does "balancing" the subjects in an experiment mean?

• Making sure all the people in each group weighs the same (group A all weigh 100 lbs; group B all weigh 125 lbs)

• Making sure the groups are balanced with the same type person (group A are all white females; group B are all black males)

• Making sure that the groups are balanced in terms of variables that could impact the study (group A and B BOTH have 2 white females and 2 black males)

Which are true of Random Assignment?

• Each subject has an equal likelihood of being assigned to a given condition.

• The gold standard for controlling potential confounding variables.

• Each subject has an equal chance to be included in the sample.

Answer explanation

Equal chance to be included in a sample is Random SELECTION - as in they are randomly selected (like put all the names in a bowl and draw names). This is NOT the same as Random Assignment

What is Matched Random Assignment?

• Twins are both placed in the same group. Another set of twins are both placed in the other group.

• Match 2 subjects who are similar on a specific difference and randomly assign them to each group (twin A is selected for group B while twin B goes to group A).

Match the following terms in experimental research.
Abbreviations used:
cond - condition; indep - independent; var - variable

• group w/o indep var;
  watch non-violent

• Indepedent variable

• cond being tested;
  ex: watch violence

• Control

• result of test;
  ex: behaving violently

• Dependent variable

Which are true of Two-group research design?

• simplest form of an experiment

• Independent variable has 2 levels: experimental and control

• all factors are the same b/w 2 groups EXCEPT for the ONE independent variable

• testing if two independent variables have an effect on the dependent

• testing if ONE independent variable has an effect on the dependent

Match the following in terms of a Two-Group Research Design?

• Breastfeeding improve baby intelligence?

• Independent Variable

• Breastmilk; Formula

• Sample; Population

• 50 babies in Griffin; all human babies

• Dependent Variable

• Breastmilk or formula

• Experimental Group; Control Group

• IQ at age 8; use standardized test

• Research Question