Chapter 6 Psychology

Experiment

Experiment

A research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental process

##Independent Variable

The experimental factor that is manipulated; the variable whose effect is being studied.

##Dependent Variable

The outcome factor; the variable that may change in response to manipulations of the independent variable.

##Control Variable

a factor that is held constant to test the relative impact of an independent variable

##Population

group of individuals of the same species that live in the same area

##Representative Sample

randomly selected sample of subjects from a larger population of subjects

##Representatives

people chosen to speak or act for others

##Experimental Group

the group in an experiment that receives the variable being tested

##Control Group

the group that does not receive the experimental treatment.

##Random sampling

a method of poll selection that gives each person in a group the same chance of being selected

##Randomly assigned

Assignment of research participants to groups in an experimental study by chance

##Biases

opinions or beliefs that affect a person's ability to make fair, unclouded judgments or decisions

##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 or advertising bias

Occurs often in medical research, when people who are motivated to try something are more likely to sign up than people who are not

##Healthy user bias

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

##Single-double blind design

A clinical trial in which one party (investigator or participant) does not know which medication or placebo is adminstered to the subject.

##Placebo

A harmless pill, medicine, or procedure prescribed more for the psychological benefit to the patient than for any physiological effect.

##Correlational research

research that seeks to identify whether an association or relationship between two factors exists

##Confounding extraneous variable

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

##Surveys

Questionnaires and interviews that ask people directly about their experiences, attitudes, or opinions.

##Longitudinal studies

A research method that studies the same participants multiple times over a period of time

##Cross- sectional studies

A type of research design that compares individuals of different ages to determine how they differ

##Clinical research

A structured process of investigating facts and theories and exploring connections

##Case studies

studies that involve extensive, in-depth interviews with a particular individual or small group of individuals

##Generalizable

Characteristic of a sample that refers to the degree to which findings based on the sample can be used to make accurate statements about the population of interest.

##Conceptual

the theory or issue being studied

##Operational

describes what the behavior looks like so two independent observers can recognize + record the same behavior

##Internal validity

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

##External validity

an attribute of an experiment in which variables have been defined in a normal, typical, or realistic way

##Reliability

consistency of measurement

##Inter-rater reliability

indicates how consistent scores are likely to be if the responses are scored by two or more raters using the same item.

##Naturalistic observation

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

##Descriptive statistics

numerical data used to measure and describe characteristics of groups. Includes measures of central tendency and measures of variation.

##Inferential statistics

numerical methods used to determine whether research data support a hypothesis or whether results were due to chance

##Central tendency

a number that describes something about the "average" score of a distribution ( mean, median and mode)

##Mean

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

##Mode

the most frequently occurring score(s) in a distribution

##Bimodal

two modes

##Median

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

##Normal curve

the bell-shaped curve that describes the distribution of many physical and psychological attributes. Most scores fall near the average, and fewer and fewer scores lie near the extremes

##Range

the difference between the highest and lowest scores in a distribution

##Variability

in a set of numbers, how widely dispersed the values are from each other and from the mean

##Standard deviation

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

##Percentile

A point on a ranking scale of 0 to 100. The 50th percentile is the midpoint; half the people in the population being studied rank higher and half rank lower.

##Positive skew

Mean and median is greater than the mode.

##Negative skew

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

##Correlation coefficient

a statistical measure of the extent to which two factors vary together, and thus of how well either factor predicts the other

##Pearson correlation coefficient

a statistical measure of the strength of a linear relationship between two metric variables

##Positive correlation

A correlation where as one variable increases, the other also increases, or as one decreases so does the other. Both variables move in the same direction.

##Negative correlation

the relationship between two variables in which one variable increases as the other variable decreases

##Sample size

The number of subjects used in an experiment or study. Generally, the larger the better.

##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.

##Alternative hypothesis

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

##Alpha

level of significance, probability that the results of an experiment can be attributed to chance rather than the manipulation of the independent variable.

##Type 1 error

rejecting the null hypothesis when it is true (false positive)

##Type 2 error

Accepting null hypothesis when you should have rejected it

##P-value

The probability level which forms basis for deciding if results are statistically significant (not due to chance).

##Deception

misleading participants about the true purpose of a study or the events that will actually transpire

##Confidentiality

the assurance that messages and information are available only to those who are authorized to view them

##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

##Confederates

in psychological and social research, a confederate is a person who is working with the experimenter and posing as a part of the experiment, but the subjects are not aware of this affiliation

##institutional Review Boards

groups of psychologists or other professionals who look over each proposed research study and judge it according to its safety and consideration for the participants in the study

##Informed consent

giving potential participants enough information about a study to enable them to choose whether they wish to participate

##Debriefing

the postexperimental explanation of a study, including its purpose and any deceptions, to its participants##