Experimental Psychology Test 2

Negatively skewed distribution

A difficult test in which most of the class did badly would form a…

Descriptive Statistics

Used to describe the data and a way to visualize the data; the first step in any statistical analysis.

Standard Deviation

On average, how far the points of data are from the mean. Found by computing the variance and taking the square root of the variance.

Linear Relationships

Correlation coefficients are sensitive only to __________ ____________. This means that the points of a scatter plot cluster around a straight line.

A Type I Error

A researcher conducts a study on grades of students who live in apartments compared with those who live in dorms. In actuality, the grades are equivalent in both groups. After statistical analysis, the researcher makes the decision to reject the null hypothesis. This decision is…

Inferential Statistics

Used to draw inferences about populations on the basis of samples; provide an objective way of quantifying the strength of the evidence for a hypothesis.

Population

The larger groups of all participants of interest

Sample

A subset of the population.

Sampling Error

Samples almost never represent populations perfectly; not really an error, just the natural variability that you can expect from one sample to another.

Null Hypothesis

States that there is NO difference between the population means.

Rejecting the Null Hypothesis

Suggests that there is a difference in the populations sampled.

Failing to Reject the Null Hypothesis

Suggests that there is no difference in the populations sampled.

Alpha

The statistical decision criteria used in testing the null hypothesis (usually .05 or .01).

Type I Error

Null hypothesis is true, but it is rejected.

Type II Error

Null hypothesis is false, but it is retained.

t-test

Tests mean difference of two groups

Analysis of variance

Tests mean differences in two or more groups.

Effect size

Indicates the size of the group differences expressed in standard deviation units. It is NOT affected by the size of the sample.

Low-Constraint Research

Can negate a general proposition but cannot establish a general proposition.

Levels of Field Research

Naturalistic Observation

Archival Research

Surveys

Case Studies

Program Evaluation

Field Experiments

When to use naturalistic observation and case-study research.

For questions involving the natural flow of behavior

When first studying a research area

When testing the feasibility of a procedure

As a way of discovering contingencies

When interested in a single individual

To test the generalizability of laboratory findings

Information Gained from Naturalistic Observation and Case-Study Research

Provides new descriptive information

Can suggest hypotheses for later higher-constraint research

Can negate a general proposition

Provides information about contingencies

Unobtrusive Observations

Observing behavior without participants’ knowledge

Participant observation

Observing behavior while participating in the situation

He would have to get the consent of each parent before beginning his observations.

Davis studied the use of corporal punishment by parents in shopping malls. What type of informed consent would he have needed for that study?

Ex Post Facto Fallacy

Interpreting an observed contingency as if it represented a causal connection.

Experimenter Reactivity

Any action by researchers that tends to influence the response of participants.

Experimenter Bias

Any impact that the researcher’s expectations might have on the observations or recording of those observations.

The prediction of future events

One of the most important uses of a correlation is its potential use in…

Correlational Research

Quantifies the strength of the relationship among two or more variables. Can be used for prediction; cannot prove a theory but could negate theory.

Differential Research

Compares two or more preexisting groups.

Cross-Sectional Research

Different participants of various ages are compared at one point in time to determine age-related differences.

Longitudinal Research

The same participants are studied at various ages to determine age-related changes.

Confounding

Occurs when two variables vary together; need to have them vary independently, usually by holding all but one variable constant.

Experimenter expectancy

Researchers tending to see what they expect to see. Can be controlled by using objective measures whenever possible.

Experimenter reactivity

Researchers unconsciously influencing participants. Can be controlled by minimizing experimenter contact.

Measurement reactivity

Participants responding differently because they know they are being observed. Can be controlled by using filler items to distract participants, using unobtrusive measures when possible, and separating measurements in time.

Moderator Variable

A variable that seems to modify the relationship between other variables.

Differential research

Men and women are compared on their knowledge of political events. This is an example of…

t-test or ANOVA

Types of tests for Score data.

Mann-Whitney U-test

Type of test for Ordinal data.

Chi Square

Type of test for Nominal data.