Chapter 2: Research Methods

double-blind procedure

double-blind procedure

an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.

survey

a technique for ascertaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group

validity

the extent to which a test measures or predicts what it is supposed to

Random assignment

the process by which participants are put into a group, experimental or control

population

the group from which a sample is selected

hypothesis

a statement of a possible relationship between two or more variables

statistical significance

how likely it is that an obtained result occurred by chance

p-value

The probability level which forms basis for deciding if results are statistically significant [5% or less] (not due to chance).

sampling

process by which participants are selected

sampling error

an error that occurs when a sample somehow does not represent the target population

Participant Bias (Response Bias)

tendency for subjects to behave in certain ways based on their perception of an experiment

correlation

a statistical measure of the relationship between two variables

case study

research method that involves an intensive investigation of one participant or small group of participants

Hawthorne effect

A change in a subject's behavior caused simply by the awareness of being studied

random selection

procedure that ensures every person in a population has an equal chance of being chosen to participate

experimenter bias

the unconscious tendency for researchers to treat members of the experimental and control groups differently to increase the chance of confirming their hypothesis

applied research

research that psychologists conduct to solve practical problems

naturalistic observation

watching behavior in real-world settings without trying to manipulate the situation

experiment

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

normal curve (normal distribution)

a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean (about 68 percent fall within one standard deviation of it) and fewer and fewer near the extremes.

inferential statistics

numerical data that allow one to generalize- to infer from sample data the probability of something being true of a population

Theory

A hypothesis that has been tested with a significant amount of data

confounding variable

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

hindsight bias

the tendency to believe, after learning an outcome, that one would have foreseen it

operational definition

a statement of the procedures used to define research variables

Reliability

consistency of measurement

basic research

pure research that aims to confirm an existing theory or to learn more about a concept or phenomenon

descriptive statistics

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

journal

a periodical that publishes technical and scholarly material, usually in a narrowly defined area of inquiry

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.

experimental group

the group in an experiment that receives the variable being tested

control group

In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.

random assignment

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

correlation coefficient

a statistical index of the relationship between two things (from -1 to +1)

meta-analysis

a "study of studies" that combines the findings of multiple studies to arrive at a conclusion

Replication

repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding extends to other participants and circumstances

halo effect

when someone's overall evaluation of a person, object, or institution spills over to influence more specific ratings

social desirability bias

A tendency to give socially approved answers to questions about oneself.

anecdotal evidence

consists of personal stories about specific incidents and experiences

positively skewed distribution

A distribution where the scores pile up on the left side and taper off to the right.

negatively skewed distribution

asymmetric distribution in which the majority of the data is concentrated to the right of the mean

standard deviation

a computed measure of how much scores vary around the mean score

mean

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

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

Percentile

Specific point in a distribution of data that has a given percentage of cases below it.

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.

Variables

Any measurable conditions, events, characteristics, or behaviors that are controlled or observed in a study.

peer review process

a procedure in which experts in a particular area evaluate papers submitted to scientific journals

extraneous variables

any variables other than the independent variable that seem likely to influence the dependent variable in a specific study

placebo effect

the phenomenon in which the expectations of the participants in a study can influence their behavior

sampling bias

A problem that occurs when a sample is not representative of the population from which it is drawn.

frequency distribution

an arrangement of data that indicates how often a particular score or observation occurs

histogram

a bar graph depicting a frequency distribution

frequency polygon

A line figure used to present data from a frequency distribution

Variability

The extent to which the scores in a data set tend to vary from each other and from the mean.

correlation coefficient

a statistical index of the relationship between two things (from -1 to +1)

Scatterplot

a graphed cluster of dots, each of which represents the values of two variables

Debriefing

the post-experimental explanation of a study, including its purpose and any deceptions, to its participants

deception

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

informed consent

an ethical principle that research participants be told enough to enable them to choose whether they wish to participate

Informed Assent

Participant's agreement to participate in the absence of full understanding
Commonly applies to individuals who have not attained legal majority and/or capacity

self-report bias

data collected directly from participants, typically by means of interviews or questionnaires

third variable problem

A problem that occurs when the researcher cannot directly manipulate variables; as a result, the researcher cannot be confident that another, unmeasured variable is not the actual cause of differences in the variables of interest.

Qualitative measures

Data not recorded in numerical form

quantitative measures

units of measure expressed in numerical terms

Generalizability

the extent to which we can claim our findings inform us about a group larger than the one we studied

falsifiable

able to be disproven by experimental results