Unit 0: Vocab: Science Practices 65 Terms

AP Psychology Unit 0 - Scientific Research

Overconfidence

A cognitive bias that leads individuals to overestimate their abilities, knowledge, or predictions, often resulting in poor decision-making.

hindsight bias

the tendency to believe, after learning an outcome that one would have foreseen it (also known as I-knew-it-all-along phenomenon)

Central tendancy

The statistical phenomenon where data points are grouped around a central value, often measured using mean, median, or mode.

hypothesis

a testable prediction, often implied by a theory

operational definition

a carefully worded statement of the exact procedures (operations) used in a research study. For example, human intelligence may be operationally defined as what an intelligence test measures

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

case study

an observation technique in which one person is studied in depth in the hope of revealing universal principles

Percentile Rank

a statistical measure that indicates the value below which a given percentage of observations fall, often used in educational testing to compare an individual's score to a norm group.

population

all the cases in a group being studied, from which samples may be drawn

random sample

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

naturalistic observation

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

correlation

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

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. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation (little scatter indicates high correlation).

placebo

a substance or treatment with no therapeutic effect used as a control in testing new drugs.

random assignment

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

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.

placebo effect

experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent

experimental group

in an experiment, the group that is exposed to the treatment, that is, to one version of the independent variable

control group

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

independent variable

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

confounding variable

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

dependent variable

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

mode

the most frequently occurring score(s) in a distribution

mean

the arithmetic average if 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 and half are below

range

the difference between the highest and lowest scores in a distribution

standard deviation

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

normal curve (normal distribution)

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

informed consent

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

debriefing

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

Structured interviews

a research method involving standardized questions asked in a predetermined order to ensure consistency across interviews.

regression toward the mean

the tendency for extreme or unusual scores to fall back (regress) toward the average.

Likert Scales

A rating scale commonly used to measure attitudes or opinions, consisting of a set of statements and a range of response options. Response options like "Strongly Agree" to "Strongly Disagree". Popular examples include 5-point scales with a neutral midpoint

statistical significance

a statistical statement of how likely it is that an obtained result occurred by chance

Informed assent

Different from consent, minors or those unable to give consent. Can be obtained from parent or guardian, or the participant themselves. Must be able to indicate agreement to participate and understanding they may withdraw.

It ensures that participants understand the study's nature and their rights.

bimodal distribution

A frequency distribution having two different values that are heavily populated with cases

Representation of participants

in a study to ensure that results are generalizable to the larger population.

confidentiality

A principle of professional ethics requiring researchers to limit the disclosure of research participants and survey respondents' identity and any unique data collected during a study.

confirmation bias

A tendency to search for information that supports our preconceptions and to ignore or distort contradictory evidence

convenience sampling

Any process for selecting a sample of individuals or cases that is neither random nor systematic but rather is governed by chance or ready availability. Data obtained from this method do not generalize to the larger population as there may be significant bias.

cultural norm

A societal rule, value, or standard that delineates an accepted and appropriate behavior within a culture.

deception

Any distortion of or withholding of fact with the purpose of misleading others.

directionality problem

In correlational research, the situation in which it is known that two variables are related although it is not known which is the cause and which is the effect.

effect size

A quantified measure of the strength or magnitude of the relationship between two variables in a statistical analysis, indicating the practical significance of the results.

experimenter bias

Occurs when a researcher's expectations or preferences about the outcome of a study influence the results obtained

falsifiable/falsifiability

The principle that for a hypothesis or theory to be considered scientific, it must be possible to conceive of evidence that would prove it false.

generalizability

Degree to which a study's findings based on a sample apply to the entire population (provided the sample is representative and large enough)

Institutional Review Board (IRB)

A committee at each college/university where research is conducted to review every experiment for ethics and methodology.

meta-analysis

A procedure for statistically combining the results of many different research studies

negative correlation

A relationship between two variables in which the value of one variable increases as the value of the other decreases.

negative skew

The degree to which a set of scores, measurements, or other numbers are asymmetrically distributed with a majority toward the high end of the distribution with a few extreme scores toward the low end.

peer review

The evaluation of scientific, academic, or professional work by others in the same field to ensure its quality and validity before publication or presentation.

positive correlation

A relationship between two variables in which both rise and fall together.

positive skew

The degree to which a set of scores, measurements, or other numbers are asymmetrically distributed with a majority toward the low end of the distribution with a few extreme scores toward the high end.

protection from harm

Reasonable steps taken to avoid and minimize adverse effects for research participants where it is foreseeable and unavoidable.

qualitative research methods

Research that focuses on gathering and analyzing non-numerical data, such as observations, interviews, or textual analysis, to understand meanings, experiences, or perspectives.

quantitative research methods

Research that focuses on gathering and analyzing numerical data to understand relationships, patterns, or trends.

representative sample

the selection of study units (e.g., participants, homes, schools) from a larger group (population) in an unbiased way, such that the sample obtained accurately reflects the total population.

sample

"A relatively small proportion of people who are chosen in a study so as to be representative of the whole.

single-blind study

Research design in which participants don't know whether they are in the experimental or control group.

social desirability bias

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

third variable problem

An undiscovered causative variable. When a relationship is found between variables x and y, variable x may erroneously be thought to be the cause of y. However, the cause of y may be a hidden variable z that is correlated with variable x.

variation

The square of the standard deviation (gives the same information as standard deviation in that it tells how spread out the data are)