Introduction to Research Methods in Psychology Exam Terms

Flashcards summarizing key terms and definitions from the lecture notes on research methods in psychology.

Dependent variable

What the experimenter measures or records; value depends on the level of the independent variable.

Independent variable

What the experimenter manipulates; must have at least 2 levels; suspected cause of an effect.

Observed score

Components: true score, systematic error, and random error.

True score/value

Measure obtained by independent and different procedures free from error.

Measurement bias

Nonrandom error in one direction.

Systematic error

Variable acts on the response in the same direction and by the same amount every time.

Random error

Variable acts on the response by different amounts and could be in different directions.

Accuracy

Degree to which observed value matches true value.

Face Validity

Content of the test is appropriate.

Criterion-Related Validity

Test score predicts future behavior (predictive validity) and test scores correlated with current behavior (concurrent validity).

Predictive validity

Test scores are correlated with behavior obtained at some later time.

Concurrent validity

Test scores are correlated with currently obtained behavior.

Convergent validity

Extent to which the scale correlates with measures of the same or related concepts.

Discriminant validity

Extent to which the scale does not correlate with measures of unrelated concepts.

Construct Validity

Successful operationalization and measurement of constructs of interest.

Descriptive statistics

Use data to describe population in graphs and summary statistics.

Normal distribution

Function that represents distribution of many random variables as a symmetrical bell-shaped graph.

Outlier

Infrequent observations; data points that do not follow the characteristic distribution of remaining data.

Nominal scale

Category information.

Ordinal scale

Category and rank order information.

Interval scale

Category and rank order information and equidistance.

Ratio scale

Category and rank order information, equidistance, and true zero.

Statistical conclusion validity

Degree to which conclusions drawn from statistical analyses of data are accurate.

External validity

Generalizability; extent to which results can be generalized beyond the sample.

Inferential statistics

Use random sample of data taken from population to make inferences about population.

Chi-square goodness of fit test

Statistical test used to test hypotheses about observed and expected frequencies across categories.

ANOVA

Analysis of variance; tests for significant differences between means.

Null hypothesis

Hypothesis that there is no effect of the treatment.

Alpha level

Fixed probability of rejecting the null hypothesis when it is true.

Effect size

Measures of the magnitude or meaningfulness of a relationship between two variables.

Independent variable (again)

What the experimenter manipulates; must have at least 2 levels.

Matched-group design

Participants are equated on a relevant subject variable prior to random assignment.

Subject reactivity

Participants behave differently because they know they are part of a study.

Double-blind control

Both participants and experimenters are unaware of the experimental conditions.

Control variable

Variable that is held constant to remove its effects on the response measure.

Quasi-experiments

Research designs that include at least one non-manipulated variable.

Ceiling effect

Measurement issue where no change occurs because the dependent variable is already at its maximum value.

Validitymeasuring what (construct) you think you’re measuring

measuring what (construct) you think you’re measuring

Types of Validity

face, criterion-related, content, internal, external, statistical

conclusion, and construct

Research question

hypothesis about the relationship between the

independent variable and the dependent variable

Mean

the middle (or average)

Median

unbiased middle (small to large)

Mode

most frequent value

standard deviation

measure of variation around mean either above or below the mean in one direction

range

subtracting smallest from largest

variance

measure of spread in data values simultaneously above and below mean

Construct validity

successful operationalization and measurement of
constructs of interest; measuring the same thing
repeatedly

Direct replication

the process of repeating a study with different data under
similar conditions, or of conducting several different
studies with the same data

Systematic or conceptual replication

the process of conducting a study again but with certain consistent differences, often in an attempt to extend the original research to different settings or participants

subject pool

undergraduate students enrolled in courses that require
participation in research for course credit

ecological validity

setting representativeness; the degree to which the research setting reproduces the real-world variables

mundane realism

the degree of similarity between the laboratory setting to real wordd settings

experimental realism

the degree to which situations are real and impactful to participants

extraneous variable

variable the experimenter is not interested in that is left
free to vary and could potentially affect the dependent
variable; potential confound

confound

something other than the independent variable(s) which
systematically varies across groups and values of
dependent measure are expected to increase with
intervention

internal validity

independent variable (and nothing else) was responsible
for differences/changes in the dependent variable;
determine if study methodologically is sound

validity

measuring what construct you think you are measuring

treatment integrity

procedural validity; measures of accuracy and reliability for
the independent variable

Subject/Participant representativeness

subjects not randomly selected from population and any

effects found could be due to existing differences between

participants and not independent variable (i.e., gender,

age, socio-economic status, education, etc.)

Setting representativeness

ecological validity; the degree to which the

Generalizability

external validity; the extent to which the results of research

(or testing) can be generalized beyond the sample that

generated them

linear regression

estimates of value of continuous output variable from

some input variables by plotting them on a line

Independent-samples t-test

used to test hypotheses about population mean when

sample size is intermediate with a normal distribution and

participants belong to two different groups

Dependent-samples t-test

used to test hypotheses about population mean when

sample size is intermediate with a normal distribution and

the same participants experience both conditions of the

independent variable

Statistical significance

estimated measure of degree to which result for a sample

is representative of population, p0.05

Null hypothesis

hypothesis that there is no effect of the treatment

alternative hypothesis

hypothesis that there is an effect of the treatment

p-value

probability of error involved in getting observed or more

extreme result if null hypothesis is true

Eta squared

effect size estimate for ANOVAs; the value is the

percentage of variance in the dependent variable

accounted for by the treatment

cohen’s d

effect size estimate; the value is the distance in standard

deviations between the mean of the null distribution and

the alternative distribution

Failing to reject the null hypothesis

the obtained p-value associated with a statistical test is

larger than the critical alpha level (or chosen significance

level), and any experimental effects are not different from

chance variance

Rejecting the null hypothesis

the obtained p-value associated with a statistical test is

smaller than or equal to the critical alpha level (or chosen

significance level), and any experimental effects are likely

not due to chance varianc

level

condition in experiment

factor

independent variable

Between-subjects design

each subject receives only one level of independent

variable; compare groups of subjects

Cross-sectional design

a research design in which individuals, typically of different

ages or developmental levels, are compared at a single

point in time

Cohort effect

any outcome associated with being a member of a group

whose members all undergo similar experiences

Experimenter bias

data collection and/or analyses affected by knowledge of,

or vested interest in, desired outcome

Single-blind control

procedure in which participants are unaware of the

experimental conditions under which they are operating,

but the experimenter knows

Placebo control

a group of participants in a study who receive an inert

substance (i.e., placebo) instead of the active drug under

investigations

Placebo Effects

tendency to report improvement/treatment is effective

because expect that

Demand characteristics

in an experiment, cues that may influence or bias

participants’ behavior and therefore distort the findings of a

study

Deception

any distortion of or withholding of fact with the purpose of

misleading others so that participants will behave as they

typically would in an experiment

Ex post facto design

research that examines past occurrences in order to

understand a current state but with an independent

variable that the experimenter cannot manipulat

interrupted time series design

take repeated measures before and after treatment;

treatment “interrupts” measures; O = outcomes, T =

treatment; nonrandom assignment

Subject variable

an experience or characteristic of a research participant
that is not of primary interest but nonetheless may
influence study results and thus be accounted for during
experimentation or data analysis that is not manipulated by
the experimenter

Extraneous variable

variable the experimenter is not interested in that is left

free to vary and could potentially affect the dependent

variable; potential confound

Confound

something other than the independent variable(s) which

systematically varies across groups and values of

dependent measure are expected to increase with

intervention

Selection bias

selection effects; any effects are due to initial group
differences (prior to study) and not independent variable

Posttest only design

subjects measured once, after the treatment

(e.g., therapy and then rating test); includes manipulation

Pretest-posttest design

subjects measured before and after the treatment

(e.g., rating test, therapy, and a second rating test);

includes manipulation and comparison

Pretest-posttest with nonequivalent control group

participants not randomly assigned to groups; Group 2

(control) does not get the treatment/intervention; both

groups measured before Group 1’s intervention and after

History

other variables operating with treatment; only those

occurring once independent variable has begun and

operating prior to assessment

Regression to the mean

extreme scores on an initial test become less extreme on a

second test

Random assignment

experimenter randomly determines how participants from

the sample will be assigned to groups/conditions