exam #2 Flashcards
How do studies using the experimental research strategy differ from other types of research?
Only experiments can demonstrate a cause-and-effect relationship between variables.
Dr. Jones is interested in studying how indoor lighting can influence people’s moods during the winter. A sample of 100 households is selected. Fifty of the homes are randomly assigned to the bright-light condition where Dr. Jones replaces all the lights with 100-watt bulbs. In the other 50 houses, all the lights are changed to 60-watt bulbs. After two months, Dr. Jones measures the level of depression for the people living in the houses. In this example, how many dependent variables are there?
1
Research indicates the people who suffer from depression also tend to experience insomnia. However, it is unclear whether the depression causes insomnia or the lack of sleep causes depression. What problem is demonstrated by this example?
the directionality problem
In an experiment, what is the purpose for manipulating the independent variable?
It helps establish the direction of the relationship and it helps eliminate the third-variable problem.
In order to establish an unambiguous relationship between two variables, it is necessary to eliminate the possible influence of which of the following variables?
Confounding variables
Which of the following characteristics are necessary for an extraneous variable to become a confounding variable?
It must change systematically when the independent variable is changed.
In an experiment comparing two treatments, the researcher assigns participants to treatment conditions so that each condition has fifteen 7-year-old children and ten 8-year-old children. For this study, what method is being used to control participant age?
Matching
Holding a variable constant is a technique for removing one threat to ________, but it can limit the ________ of an experiment.
internal validity, external validity
Which of the following is the primary goal for randomly assigning participants to treatment conditions in an experiment?
Minimize the likelihood that a participant variable (such as age or gender) becomes a confounding variable
What is the purpose for using a control condition in an experiment?
It provides a baseline that can be used to evaluate the size of the treatment effect.
An experiment includes a treatment condition, a no-treatment control, and a placebo control. Which two conditions should be compared to determine the size of the effect that is actually caused by the treatment?
Placebo versus treatment
A researcher exposes people to a stressful situation (such as public speaking) to examine the effect of stress on depressed mood. Why would the researcher also include a measure of stress?
It is a manipulation check.
A researcher moves an experiment out of the laboratory and into the real world. This type of research is called
a field study.
Researchers often use simulation experiments in an attempt to obtain the _________ of an experiment and still keep much of the _________ of research conducted in the real world.
internal validity, external validity
Although field studies tend to have higher external validity than traditional laboratory studies, what risk do they tend to have?
Lower internal validity
Which statement best characterizes a between-subjects experimental design?
Each participant is assigned to one condition of the experiment.
Which of the following accurately describes the scores in a between-subjects experiment?
Only one score is obtained for each participant.
If a between-subjects experiment produces 50 scores in treatment 1 and 50 scores in treatment 2, then how many participants were in the entire experiment?
100 participants
In a between-subjects experiment, if the participants in one group have characteristics that are different from the participants in another group, then which of the following is threatened?
Internal validity
For a between-subjects experiment, which of the following is a possible threat to internal validity?
Individual differences that exist between treatments
Which of the following does not guarantee that a specific participant variable will not become a confounding variable?
Randomizing the variable across treatment
Which of the following is a limitation of using matching rather than random assignment to form groups in a between-subjects experiment?
Matching requires another measurement procedure.
How does holding a variable constant prevent the variable from becoming a confound?
It eliminates the possibility that the variable will be substantially different from one group to another.
variance
a statistical value that measures the size of the differences from one score to another
Whenever there are large differences between ___, there is large ___.
individuals; variance
true or false: with between subjects design we want to minimize variance within treatments
true
what is it best way to minimize the negative consequences of high variance?
- standardize treatments
- minimize individual differences between the participants
what happens when you minimize individual differences?
you lessen external validity
Which of the following maximizes the likelihood of a successful research result?
Increase the differences between treatments and decrease the variance within treatments
Which of the following is an option for limiting the variance within treatment conditions?
Hold a participant variable constant
Which of the following is a potential problem with holding a participant variable constant?
It threatens the external validity of the study.
define: differential attrition
refers to differences in attrition rates from one group to another and can threaten the internal validity of a between-subjects experiment