Unit 1 AP Psych

3 types of research in psychology

experimental, correlational, and clinical

Experiment

An investigation seeking to understand the relations of cause and effect

Independent Variable

manipulated variable

Dependent Variable

what is measured

control variable

A variable that is kept constant during a controlled experiment

population

a group of interest

representative sample

randomly selected sample of subjects from a larger population of subjects

Representativeness

the degree to which a sample reflects the diverse characteristics of the population that is being studied

Random Sampling

ensures maximum representativeness

Sampling Bias

a flawed sampling process that produces an unrepresentative sample

Bias of Selection

systematic difference in the enrollment of participants in a study that leads to an incorrect result (e.g., risk ratio or odds ratio) or inference.

Self-Selection Bias

A bias that occurs because people who feel strongly about a subject are more likely to respond to survey questions than people who feel indifferent about it.

Pre-screening/Advertising

Researchers select who they want in their study based on populations

Healthy user bias

When the study population tends to be in better shape than the general population

Correlational Research

The degree of association between two or more variables or characteristics that occur naturally

Longitudinal Studies

over long periods of time with the same subjects

Cross-Sectional Studies

test a wide array of subjects from different backgrounds to increase generalizability

• less expensive, time-consuming, and easier to conduct

• However, some relationships cannot be studied

• Social desirability bias

Confounding/third/extraneous variable

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

Clinical Research

case studies

• conducted under the assumption that an in-depth understanding of single cases will allow for general conclusions about other similar cases

• cannot lead to causative relationships

• Sigmund Freud and Carl Rogers used case studies for their conclusions

Conceptual Definition

the theory or issue being studied

• how drugs affect kids behavior

Operational Definition

the way that a theory or issue will be directly observed and measured

• days absent because of drugs

Operational Definitions have to be

internally and externally valid

Internal validity

The certainty with which the results of an experiment can be attributed to the manipulation of the independent variable instead of the third variable

• threatened by cofounding variables

External Validity

The extent to which the findings of a study can be generalized to other contexts in the real world

• threatened by artificiality

reliability

whether or not the same results appear if the experiment is repeated under similar conditions

Inter-rater reliability

The degree to which different raters agree on their observations of the same data

naturalistic observation

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

• disadvantage is the difficulty of controlling the extraneous variables

Descriptive Statistics

summarize data

Inferential Statistics

allows researchers to test hypotheses about data and determine how confident they can be in their inferences about data

Central Tendency

mean, median, mode (characterizes a typical value)

Normal Curve

median=mode=mean

Variability

How much do the numbers in the set differ from one another

Positive Skew

means most of the values are on the lower end but there are some exceptionally large values

Negative Skew

Most values are on the higher end, but there are some exceptionally small values

Correlation Coefficient

how much two things relate to each other

Pearson correlation coefficient

The most common statistical measure of the strength of linear relationships among variables

Stanley Milgram

obedience to authority; had participants administer what they believed were dangerous electrical shocks to other participants; wanted to see if Germans were an aberration or if all people were capable of committing evil actions

Institutional Review Boards

An organization that must assess research plans before the research is approved to ensure that it meets all ethical standards

Alpha

the accepted probability that the result of an experiment can be attirbuted to chance rather than the manipulation of the independent variable

Type 1 Error

a conclusion that a difference exists when this difference doesn't exist

Type 2 Error

refers to the conclusion that there is no difference when there is a difference

p-value

The probability of making a Type I error and it indicates that the results are statistically significant (if p=.05 then 5%of making a type 1 error)