Exam 2 - Psych 355 UPDATED ACTUAL Questions and
CORRECT Answers
Systematic Variance the portion of the total variance in a set of scores that is related in an orderly,
predictable fashion to the variables the researcher is investigating
-between groups variance
Two Sources of systematic Variance -treatment variance
-primary variance
-confound variance
-secondary variance
treatment variance the portion of the systematic variance that is due to the independent variable
confound variance the portion of the total variance in a set of scores that is due to extraneous
variables that differ systematically between the experimental groups
Error variance Random variability in a set of scores that is not the result of the independent
variable. Statistically, the variability of each score from its group mean.
-within groups variance
Sources of Error Variance -individual differences
-transient states
-environmental factors
-differential treatment
-measurement error
Internal Validity the degree to which changes in the dependent variable are due to the
manipulation of the independent variable
-the degree to which a researcher draws accurate conclusions about the
effects of the independent variable on a dependent variable
-researchers must eliminate all potential confounds
threats to internal validity history, maturation, testing, instrumentation, mortality, selection bias
-history
-miscellaneous design confounds
-biased assignment of participants to conditions
-differential attrition
-pretest sensitization
External validity is the degree to which the results obtained in one study can be replicated or
generalized to other samples, research settings, and procedures
The "experimenter's dilemma" refers to the trade-off the more tightly controlled an experiment, the stronger its internal validity.
between internal and external validity however tight experimental control makes the experiment more unique and
less like other settings, thereby lowering external validity.
-experimenters almost always opt for internal over external validity
, Advantages of Web-Based Research -larger samples
-more diverse samples
-ease of obtaining a very specific groups of participants relatively quickly
-less influence of social desirability biases (because responses are anonymous)
disadvantages of web-based research -Difficult to identify the participants and ensure that a person participates only
once
-The research setting varies greatly because the participants can complete the
study wherever they choose
-Participants often fail to complete the study
-Limited in the types of research paradigms that are possible
expectations -experimenter expectancy effects occur when a researcher's expectations
about the outcome of a study influences participants reactions
-demand characteristics occur when aspects of a study indicate to participants
how they should respond
-to avoid these, researchers use double-blind procedures in which neither the
participants nor the experimenter who interacts with them know which
condition the participant is in
Placebo effect improvement resulting from the mere expectation of improvement
one-way design an experimental design with a single independent variable
-main characteristics: n of independent variables
-two-group experimental design
assigning participants to conditions -three types of one-way designs:
-randomized groups design
-matched subjects design
-repeated measures design
posttest and pretest-posttest designs -posttest only design
-pretest-posttet design
disadvantages of pretest-posttest designs -prestest sensitization
-does the added benefit outweigh the additional time/effort?
factorial designs experimental designs allowing researchers to manipulate more than one
intervention
-an experimental design in which two or more independent variables are
manipulated
CORRECT Answers
Systematic Variance the portion of the total variance in a set of scores that is related in an orderly,
predictable fashion to the variables the researcher is investigating
-between groups variance
Two Sources of systematic Variance -treatment variance
-primary variance
-confound variance
-secondary variance
treatment variance the portion of the systematic variance that is due to the independent variable
confound variance the portion of the total variance in a set of scores that is due to extraneous
variables that differ systematically between the experimental groups
Error variance Random variability in a set of scores that is not the result of the independent
variable. Statistically, the variability of each score from its group mean.
-within groups variance
Sources of Error Variance -individual differences
-transient states
-environmental factors
-differential treatment
-measurement error
Internal Validity the degree to which changes in the dependent variable are due to the
manipulation of the independent variable
-the degree to which a researcher draws accurate conclusions about the
effects of the independent variable on a dependent variable
-researchers must eliminate all potential confounds
threats to internal validity history, maturation, testing, instrumentation, mortality, selection bias
-history
-miscellaneous design confounds
-biased assignment of participants to conditions
-differential attrition
-pretest sensitization
External validity is the degree to which the results obtained in one study can be replicated or
generalized to other samples, research settings, and procedures
The "experimenter's dilemma" refers to the trade-off the more tightly controlled an experiment, the stronger its internal validity.
between internal and external validity however tight experimental control makes the experiment more unique and
less like other settings, thereby lowering external validity.
-experimenters almost always opt for internal over external validity
, Advantages of Web-Based Research -larger samples
-more diverse samples
-ease of obtaining a very specific groups of participants relatively quickly
-less influence of social desirability biases (because responses are anonymous)
disadvantages of web-based research -Difficult to identify the participants and ensure that a person participates only
once
-The research setting varies greatly because the participants can complete the
study wherever they choose
-Participants often fail to complete the study
-Limited in the types of research paradigms that are possible
expectations -experimenter expectancy effects occur when a researcher's expectations
about the outcome of a study influences participants reactions
-demand characteristics occur when aspects of a study indicate to participants
how they should respond
-to avoid these, researchers use double-blind procedures in which neither the
participants nor the experimenter who interacts with them know which
condition the participant is in
Placebo effect improvement resulting from the mere expectation of improvement
one-way design an experimental design with a single independent variable
-main characteristics: n of independent variables
-two-group experimental design
assigning participants to conditions -three types of one-way designs:
-randomized groups design
-matched subjects design
-repeated measures design
posttest and pretest-posttest designs -posttest only design
-pretest-posttet design
disadvantages of pretest-posttest designs -prestest sensitization
-does the added benefit outweigh the additional time/effort?
factorial designs experimental designs allowing researchers to manipulate more than one
intervention
-an experimental design in which two or more independent variables are
manipulated
