Psych 303 Final Umich Rabinowitz

sequential design

Combination of cross-sectional and longitudinal designs involving repeated study of different cohorts over time.

t-test

Compares mean values of a continuous variable between 2 categories/groups.

ANOVA

Compares mean values of a contributes variable for multiple categories/groups

usefulness of multiple measures

Creates a more accurate measurement

Qualitative

Data in the form of recorded descriptions rather than numerical measurements.

Quantitative

Data that is in numbers

Latin square design

a counterbalancing strategy where each experimental condition appears at every position in the sequence order equally often

matched groups

participants who are similar on some measured variable are grouped into sets; the members of each matched set are then randomly assigned to different experimental conditions

Bimodal

two peaks

observer bias

tendency of observers to see what they expect to see

mean

the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores

phi coefficient

the correlation coefficient used when both measured variables are dichotomous and nominal

internal validity

the degree to which changes in the dependent variable are due to the manipulation of the independent variable

experimental realism

the degree to which experimental procedures are involving to participants and lead them to behave naturally and spontaneously

range

the difference between the highest and lowest scores in a distribution

interaction

the effect of one factor (such as environment) depends on another factor (such as heredity)

staged manipulation

the manipulation of an independent variable that requires the participant to be "set up" to experience some stimulus or event

Median

the middle score in a distribution; half the scores are above it and half are below it

Mode

the most frequently occurring score(s) in a distribution

z-score

the number of standard deviations a particular score is from the mean

observational research

the process of watching people or animals and systematically recording how they behave or what they are doing

content analysis

the systematic coding and objective recording of data, guided by some rationale

regression toward the mean

the tendency for extremes of unusual scores to fall back (regress) toward their average

Use of confederates

using researchers staged as participants

unsystematic variability

when levels of a variable fluctuate independently of experimental group membership, contributing to variability within groups

alternative hypothesis

The hypothesis that states there is a difference between two or more sets of data.

concealed observation vs participation

The observer concealing themselves (common in wildlife) vs. participating in the study

p-value

The probability of results of the experiment being attributed to chance.

main effect

In a factorial design, the overall effect of one independent variable on the dependent variable, averaging over the levels of the other independent variable.

ceiling and floor effects

Measurement problem whereby the researcher cannot measure the effects of an independent variable or a possible interaction effect because performance has reached a maximum (or minimum) in any condition of the experiment.

Ordinal Measurement

Numbers are assigned to rank-ordered categories ranging from low to high

Outliers

Numbers that are much greater or much less than the other numbers in the set

random assignment

assigning participants to experimental and control conditions by chance, thus minimizing preexisting differences between those assigned to the different groups

systematic observation

careful observation of one or more specific behaviors in a particular setting

control group vs. experimental group

control group = placebo ; nothing happens to them experiment group = is the one being tested on

bivariate correlation

correlation between two variables

confounding variable

in an experiment, a factor other than the independent variable that might produce an effect

systematic variability

in an experiment, the situation that occurs when the levels of a variable coincide in some predictable way with experimental group membership, creating a potential confound

Variance

(n.) - a difference between what is expected and what actually occurs

naturalistic observation

observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation

carryover effects

occur when participants' experience in one condition affects their behavior in another condition of a study

ABAB design

Single-subject design A - baseline established B - treatment offered A - withdraw tx for a time B - offer tx again To show effectiveness of tx

Threats to Internal Validity: Maturation

Changes in participants over time alter DV responses above and beyond IV exposure

threats to internal validity

History Maturation Testing Instrumentation Diffusion of treatment Regression towards the mean Selection bias Attrition

r^2 (coefficient of determination)

- Proportion/Percentage of the total cost that could be explained based on our activity level.

Research Cycle

1. Formulate Question 2. Review Existing Literature 3. Select Method 4. Collect Data 5. Analyze Data 6. Report Results

Notation in Factorial Designs

2x2 2 independent variables 2 levels

Implicit Association Test

A computer-driven assessment of implicit attitudes. The test uses reaction times to measure people's automatic associations between attitude objects and evaluative words. Easier pairings (and faster responses) are taken to indicate stronger unconscious associations.

mixed factorial design

A design that includes both independent groups (between-subjects) and repeated measures (within-subjects) variables.

manipulation check

A measure used to determine whether the manipulation of the independent variable has had its intended effect on a subject

Eyeblink startle response

A motor response (measured via EMG) that is normally elicited by a loud unexpected sound but is further modulated by the participants' emotional state

cohort

A population group unified by a specific common characteristic, such as age, and subsequently treated as a statistical unit.

null hypothesis

A prediction that there is no difference between groups or conditions, or a statement or an idea that can be falsified, or proved wrong.

longitudinal study

A research approach that follows a group of people over time to determine change or stability in behavior.

between groups design

A research design in which a single individual does not provide data for more than one condition or group.

stable-baseline design

A small-N design in which a researcher observes behavior for an extended baseline period before beginning a treatment or other intervention; if behavior during the baseline is stable, the researcher is more certain of the treatment's effectiveness.

Chi-square test

A statistical method of testing for an association between two categorical variables. Specifically, it tests for the equality of two frequencies or proportions.

frequency distribution

A summary chart, showing how frequently each of the various scores in a set of data occurs

symbolic racism

A tendency to express negative biases held about a racial outgroup not at the group directly, but at social policies seen as benefiting that group.

posttest-only design

A true experimental design in which the dependent variable (posttest) is measured only once, after manipulation of the independent variable.

reversal design

A type of single-subject design that involves repeated alternations between a baseline period and a treatment period.

control variable

A variable that is kept constant during a controlled experiment. (For example: Temperature)

type 2 error

Accepting null hypothesis when you should have rejected it

EEG

An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.

double-blind study

An experiment in which neither the participant nor the researcher knows whether the participant has received the treatment or the placebo

pretest-posttest design

An experiment using an independent-groups design in which participants are tested on the key dependent variable twice: once before and once after exposure to the independent variable.

demand characteristics

Any aspects of a study that communicate to the participants how the experimenter wants them to behave.

testing effect

Enhanced performance on a memory test caused by being tested on the material to be remembered.

Expectancy effects (experimenter bias)

Expectations about how participants should respond, these expectations can in turn bias the results. May occur whenever the experimenter knows which condition the participants are in. Experimenter might unintentionally treat participants differently in the various conditions of the study. Bias can occur when experimenters record the behaviors of the participants; there may be subtle differences in the way the experimenter interprets and records the behaviors.

artificiality of experiments

Experiments in a lab do not necessarily reflect reality and can hurt external validity.

Threats to Internal Validity: History

For example, competitors change their marketing strategies during a test marketing experiment, 2 subject groups with different histories

Sample vs. Population

Population: entire group of people about which information is wanted (e.g. American adults). Sample: a part or subset of the population that is used to gain information about the whole population.

Type 1 error

Rejecting null hypothesis when it is true

quasi-experimental design

Research method similar to an experimental design except that it makes use of naturally occurring groups rather than randomly assigning subjects to groups.

alpha level

The threshold P-value that determines when we reject a null hypothesis

self-report measures

Usually questionnaires or interviews that measure how people report that they act, think, or feel.

standard deviation

a measure of variability that describes an average distance of every score from the mean

nominal measurement

a measurement in which numbers are assigned to discrete labels or categories

attrition

a natural loss of individuals

nonequivalent control group design

a quasi-experimental study that has at least one treatment group and one comparison group, but participants have not been randomly assigned to the two groups

spurious correlation

a relationship between two variables that is actually caused by a third factor

within-subjects design

a research design that uses each participant as his or her own control; for example, the behavior of an experimental participant before receiving treatment might be compared to his or her behavior after receiving treatment

theory-testing mode

a researcher's intent for a study, testing association claims or causal claims to investigate support for a theory

random sampling

a sample that fairly represents a population because each member has an equal chance of inclusion

straightforward manipulation

a situation in which materials and instructions are simply presented to respondents or subjects

pilot study

a small study carried out to test the feasibility of a larger one

multiple baseline design

a small-N design in which researchers stagger their introduction of an intervention across a variety of contexts, times, or situations

Pearson's r

a statistic that measures the direction and strength of the linear relation between two variables that have been measured on an interval or ratio scale

factorial design

a study in which there are two or more independent variables, or factors

selection effect

a threat to internal validity that occurs in an independent-groups design when the kinds of participants at one level of the independent variable are systematically different from those at the other level

post hoc tests

additional significance tests conducted to determine which means are significantly different for a main effect

multiple regression

an associative forecasting method with more than one independent variable

single-case experimental design

an experiment in which the effect of the independent variable is assessed using data from a single participant

control series design

an extension of the interrupted time series quasi-experimental design in which there is a comparison or control group

GSR (galvanic skin response)

an increase in the electrical conductivity of the skin that occurs when sweat glands increase their activity

F distribution

mathematically defined curve that is the comparison distribution used in an analysis of variance

Solomon four-group design

pretest-posttest design with two sets of nonequivalent groups, one set that takes the pretest and posttest and one set that takes only the posttest

statistically significant

refers to a result that is statistically unlikely to have occurred by chance

cross-sectional design

research design in which several different age groups of participants are studied at one particular point in time

single-blind study

study in which the subjects do not know if they are in the experimental or the control group