Exam 2 Content

Selection Bias

When the experimenter or participant chooses which group the participants are in.

Error Variance

the natural, random fluctuation in scores caused by factors other than the IV.

Quasi Experimental

a study in which groups of participants are NOT equal.

External validity

the generalizability of the results of an investigation beyond the specific participants, measures, and site of the research.

Confound

a factor that yields alternative explanations for a study's results.

Within- Subjects Design

one sample of participants is tested two or more times, providing two or more comparable scores at one testing.

Counterbalance

extraneous variables will be a part of every condition (more advantageous at yielding external validity than holding constant)

Regression toward the mean

the phenomenon in which extreme scores closer to the mean.

Pretest

given before the IV is manipulated.

Instrumentation Effect

the dependent variable is measured changes in accuracy over time.

Demand Characteristics

the cues participants use to determine what is expected of them in a study.

Convenience Sample

participants are not randomly chosen, but instead happen to be in the right place at the right time.

Reliability

the same procedures produce the same results.

Maturation effect

any changes in behavior caused by the passage of time.

Matching

identifying pairs (or more) of participants that measure similarly on a characteristic related to the DV and then randomly assigning each participant to a certain group.

Internal Validity

the extent to which the design of an experiment ensures that the IV, not some other variable, caused the measured difference in the DV.

Incomplete within subjects design

each participant receives a unique order of the conditions at least once but does not receive all possible sequences of conditions.

Longitudinal Design

looks for changes that occur over time.

Operational Definition

a definition that tells the reader exactly what was done to produce a phenomenon or to measure some variable.

Extraneous Variables

factors other than the Independent variables that could possibly affect the outcome of the study.

Pretest -Postest Design

one group of participants is tested twice using the same measurement tool, once before and after the IV is manipulated in some way.

Validity

the extent to which a measurement technique measures what it's supposed to measure.

Experimenter Effect

a confound where the experimenter affects the results.

Random Selection

all members of a population are equally as likely to be chosen.

Correlational Study

an investigation that explores the effect of a subject variable on a dependent measure.

Carryover effect

when participants perform a task numerous times, and their performance in earlier trials affects their performance in later trials.

Subject Mortality

when volunteers for the experiment are provided informed consent before the experiment begins, but quit part of the way through.

Random Assignment

use of a procedure so that each participant from the population is equally as likely to be assigned to either condition.

Systematic Subject Mortality

the participants who quit are distributed unevenly among the groups.

Operational Definition

a definition that tells the reader exactly what was done to produce a phenomenon or to measure some variable

Reliability

the same procedures produce the same results

Validity

the extent to which a measurement technique measures what its supposed to measure

Internal Validity

the extent to which the design of an experiment ensures that the IV, not some other variable, caused the measured difference in the DV

Confound

a factor that yields alternative explanations for a studys results

Experimenter Effect

a confound where the experimenter affects the results

Demand Characteristics

the cues participants use to determine what is expected of them in a study

External validity

the generalizability of the results of an investigation beyond the specific participants, measures, and site of the research

Extraneous Variables

factors other than the Independent variables that could possibly affect the outcome of the study

Random Selection

all members of a population are equally as likely to be chosen

Convenience Sample

participants are not randomly chosen, but instead happen to be in the right place at the right time

Random Assignment

use of a procedure so that each participant from the population is equally as likely to be assigned to either condition

Null Hypothesis (H0)

no difference in the groups being compared

Alternative Hypothesis (HA)

hypothesis upon which the researchers prediction is being made

Type I Error

reject the null hypothesis when it is true

Type II Error

fail to reject the null hypothesis when it is false (less serious)

Experiments

investigations in which the researcher manipulates an IV to determine if there are any differences in the DV among equivalent groups of participants

equivalent groups

the best way is random assignment

Quasi-Experimental

a study in which groups of participants are NOT equal

Correlational Study

an investigation that explores the effect of a subject variable on a dependent measure

Between-subjects design

the performance of participants in one or more groups is compared with the performance of participants in another group

Selection Bias

When the experimenter or participant chooses which group the participants are in

Matching

identifying pairs (or more) of participants that measure similarly on a characteristic is related to the DV and then randomly assigning each participant to a certain group

Pretest

given before the IV is manipulated

Within-Subjects Design

one sample of participants is tested two or more times, providing two or more comparable scores at one testing

Cross-sectional Design

used by researchers to look at differences between different age groups

Extraneous variables

variables that can affect the dependent variable

hold constant

a variable all groups in the study will have the same level of the extraneous variable

counterbalance

extraneous variables will be a part of every condition (more advantageous at yielding external validity than holding constant)

Instrumentation Effect

the dependent variable is measured changes in accuracy over time

Subject Mortality

when volunteers for the experiment are provided informed consent before the experiment begins, but quit part of the way through

Nonsystematic Subject Mortality

when a participant leaves a study for a reason unrelated to the subject of the experiment itself

Systematic Subject Mortality

the participants who quit are distributed unevenly among the groups

Comparable Treatment of Groups

the researcher treats the experimental groups as evenly as possible, except for the manipulation of the IV

Error Variance

the natural, random fluctuation in scores caused by factors other than the IV

Pretest-Postest Design

one group of participants is tested twice using the same measurement tool, once before and after the IV is manipulated in some way

Repeated-Measures Design

multiple measurements per participant, used when a single testing session the participants provide multiple pieces of data

Longitudinal Design

looks for changes that occur over time

carryover effect

when participants perform a task numerous times, and their performance in earlier trials affects their performance in later trials

practice effect

when, through repetition, the participants performance improves

fatigue effect

participants repeat the task and their performance declined

history effect

the result of an event that occurs outside the experiment at the same time that the IV is being changed

maturation effect

any changes in behavior caused by the passage of time

testing effect

when tested repeatedly, the experience on a previous test is likely to affect the results of the next test

Regression toward the mean

the phenomenon in which extreme scores closer to the mean

Counterbalancing

presenting the experimental conditions to participants in different orders so that carryover effects can be controlled

Complete within-subjects design

all the participants experience each experimental condition several times until they have each received all possible orders of the condition

incomplete within-subjects design

each participant receives a unique order of the conditions at least once, but does not receive all possible sequences of conditions