Chapter 6 Study Guide
Chapter 7 Study Guide
Chapter 8/9 Study Guides
Chapter 13 Study Guide
Chapter 14 Study Guide
100
What is external validity?
External validity refers to how well the findings of an experiment generalize to other situations or populations . . . the key point: does it GENERALIZE???
100
Does every experiment have to have a control group?
No! If you’re simply interested in the difference between two variables, a control group may not be necessary
100
What is correlational research? What makes research correlational?
Correlational research: nonexperimental research that measures two or more variables to determine the degree of relationship between them.
What makes research correlational in the common usage is the inability to manipulate some variable independently, so relationships are studied among variables, but none of which may be the actual cause of the other.
100
What is the main difference between a true experiment and a Quasi experiment?
A true experiment is one in which the experimenter has complete control over the who, what, when, where and how of the experiment. A quasi experiment, by contrast, does not permit the experimenter to control the assignment of subjects to conditions. You often need to select your subjects from pre-existing groups in a quasi experiment.
100
What are “descriptive statistics?” What are “inferential statistics?”
Descriptive statistics summarize a set of data. Inferential statistics help to draw conclusions about populations
200
What is ecological validity?
The extent to which an experimental situation mimics a real-world situation. You could think about external validity as how well an experiment generalizes to other situations, and ecological validity as how it applies to a real-world situation
200
What is a “within-subjects” design? What is a “between-subjects” design?
In a within-subjects design, each subject experiences every condition of the experiment In a between-subjects design, differences between conditions are tested between different subjects
200
What are the definitions of the terms manipulation, assignment, and observation?
Manipulation: in an experiment, conditions or variables assigned or presented to a participant
Assignment: In an experiment, pairing a subject with a condition or variable, according to the experimenter’s plan
Observation: The record of a behavior
200
What is a nonequivalent-control group design?
If both an experimental and a control group are part of an experiment but subjects have not been allocated randomly to the two groups, we have a nonequivalent-control-group design. This is the most typical quasi experimental design.
200
What are the most common descriptive statistics?
The average (a measure of central tendency) And the standard deviation (a measure of variability)
300
What is internal validity? What is confounding?
Internal validity is the extent to which a study provides evidence of a cause-effect relationship between the independent and dependent variables. Confounding is error that occurs when the effects of two variables in an experiment cannot be separated, resulting in a confused interpretation of the results
300
We need replication for the field of psychology to be true, but the people doing the work are actually often not motivated to do it!!! Why is this the case?
Direct replication is seldom carried out because finding exactly the same thing as someone else did brings little glory. More specifically, it is difficult to get grants for replications, journals tend to avoid publishing such research, and professors who spend time replicating other people’s work do not get promoted.
300
p.231 – I like the definition of “random sample” listed in the second paragraph of p.231. What is the definition of this selection process?
A selection process is random if (1) every member of the population has the same probability of being selected, and (2) selection of one individual is independent of the selection of any other.
300
What is a “repeated-treatment design?”
It’s a design in which a treatment is withdrawn and then presented a second time
300
What is the “range?”
The difference between the highest and lowest scores in a distribution. Although it is easy to compute, the range depends completely on the two extreme scores.
400
What are some example threats to internal validity? (List 3!)
1.) Ambiguous temporal precedence (correlation studies, especially. Can’t really determine cause-effect relationships if this is the case)
2.) Events outside the laboratory (especially with longitudinal studies with sessions on different days, HISTORY plays a role)
3.) Maturation (subjects changing between conditions of an experiment because of naturally occurring processes. This moreso refers to developmental studies
4.) Effects of testing (generally, people catch on to the procedure the more you test them, and get better at it)
5.) Regression effect: The tendency of subjects with extreme scores on a first measure to score closer to the mean on a second testing
6.) Selection: a bias that can occur due to the assignment of subjects to groups
7.) Mortality: the dropping out of some subjects before an experiment is completed, causing a threat to validity, because the subjects who remain may be different than the subjects who did not complete it.
400
pp.173-174 – What does “matching” refer to? Why is it important?
Matching is a control procedure to ensure that experimental and control groups are equated on one or more variables before the experiment. If subjects differ on a variable that could affect the DV, matching may be necessary
400
What is the definition of “stratified random sample?” Can you give an example?
A random sample in which two or more sub-samples are represented according to some predetermined proportion, generally in the same proportion as they exist in the population
400
What do we call the design of an experiment when there is one between-subjects variable and one within-subjects variable?
A mixed-factorial design
400
What are three advantages of computing the mean as a descriptive statistic? (This is the last question I wrote, and it's probably the hardest of anything I put on our Jeopardy boards.)
1.) It uses all of the information in the distribution (i.e., it’s influenced by every score)
2.) It is the basis of the most common and most powerful of the further statistical computations
3.) Means of subgroups may be combined to obtain the mean of the entire group (see bottom of page)
500
What are some example threats to external validity? (List 2!)
Other subjects (did you choose a representative sample???)
Other Times (would the same experiment conducted at another rtime produce the same results?)
Other Settings (does phenomena observed in your lab generalize to other labs, or to the real world?)
500
What are the two meanings of the term control in an experimental context?
(1) Something that provides a standard against which to compare the effect of a particular independent variable.
(2) It is the ability to restrain or guide sources of variability in research Limiting the things that change to those mandated by the experimental design (such as the IV) reduces the chances of confounding variables or measurement error and increases our confidence in the experimental results.
500
What is a “cluster sample?” Can you give an example?
Group selected by using clusters or groupings from a larger population.
Example: selective one-tenth of classes at a college, and then sampling all students within each selected class
500
What is an “interrupted time-series design?”
A research design that allows the same group to be compared over time by considering the trend of the data before and after experimental manipulation
500
What is the “variance?” What is the “standard deviation?”
Variance: The average of the squared deviations from the mean.
Std Deviation: The square root of the variance; a measure of variability in the same units as the scores being described.
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