Psychology 1 - Chapter 2 Terms

Sampling Bias

A bias that occurs when the participants or items are not chosen at random, but instead are chosen so that one attribute is over-or underrepresented.

Control Condition

A condition administered to the same participants who receive the experimental condition; this effectively makes the participants both the experimental and the control group.

Operational Definition

A definition of a variable that specifies how it is measured or manipulated.

Sample

A group that is drawn from a larger population and measured or observed.

Control Group

A group that is treated exactly the same way as the experimental group, except that the one aspect of the situation being studied is not manipulated for this group. The control group holds constant - "controls" - all of the variables in the experimental group except the one of interest.

Experimental Group

A group that receives the complete procedure that defines the experiment.

Validity

A measure is valid if it does in fact measure what is supposed to measure.

Placebo

A medically inactive substance that is presented as though it has medicinal effects.

Experimental Condition

A part of a study in which the participant receives the complete procedure that defines the experiment. Usually this is accomplished by a control condition, with the same participants receiving both experimental and control conditions.

Case Study

A scientific study that focuses on a single instance of a situation, examining it in detail.

Survey

A set of questions, typically about beliefs, attitudes, preferences, or activities.

Meta-Analysis

A statistical technique that allows researchers to combine results from different studies, which can determine whether there is a relationship among variables that transcends any one study.

Response Bias

A tendency to respond in a particular way regardless of respondents' actual knowledge or beliefs.

Hypothesis

A tentative idea that might explain a set of observations.

Variable

An aspect of a situation that can vary, or change: specifically, a characteristic of a substance, quantity, or entity that is measurable.

Bias

An effect that occurs when beliefs, expectations, or habits alter how participants in a study respond or affect how a researcher sets up or conducts a study, thereby influencing its outcome.

Prediction

An expectation about specific events that should occur in particular circumstances if the theory or hypothesis is correct.

Confound

An independent variable that varies along with the ones of interest, and could be the actual basis for what you are measuring.

Correlation Coefficient

An index of how closely interrelated two sets of measured variable are, which ranges from -1.0 to +1.0. The higher the correlation (in either direction), the better we an predict the value of one type of measurement when given the value of the other.

Theory

An interlocking set of concepts or principles that explain a set of observations.

Sampling Error

Any difference that arises from the luck of the draw, due to nonrandom sampling from a population, not because two samples are in fact representative of different populations.

Replication

Collecting the same observations or measurements and finding the same results as were found previously.

Descriptive Statistics

Concise ways of summarizing properties of sets of numbers.

Reliability

Data are reliable if the same results are obtained when the measurements are repeated.

Experimenter Expectancy Effects

Effects that occur when an investigator's expectations lead him or her (consciously or unconsciously) to treat participants in a way that encourages them to produce the expected results. Ex: Clever Hans horse in 1890's.

Step 3 of Scientific Method

Forming a Hypothesis

Step 5 of Scientific Method

Formulating a Theory. Keyword: Predictions.

Quasi-Experimental Design

Includes independent & dependent variables as usual, but participants are not randomly assigned to conditions, and the conditions typically are selected from naturally occurring variations in situations.

Raw Data

Individual measurements, taken directly from the situation being studied.

Experimental Research/Method

Involves manipulating one variable to determine if changes in one variable cause changes in another variable. This method relies on controlled methods, random assignment and the manipulation of variables to test a hypothesis.

Descriptive Research

Naturalistic Observations, Case Studies, & Surveys.

Statistics

Numbers that summarize or indicate difference or patterns of differences in measurements.

Data

Objective observations.

Step 2 of Scientific Method

Observing Events

Step 1 of Scientific Method

Specifying a Problem

Step 4 of Scientific Method

Testing the Hypothesis. Keyword: Operational Definition.

Step 6 of Scientific Method

Testing the Theory.

Mean

The arithmetic average.

Independent Variable

The aspect of the situation that is intentionally varied while another aspect is measured.

Dependent Variable

The aspect of the situation that is measured as an independent variable is changed: the value of the dependent variable depends on the independent variable.

Central Tendency

The clustering of the most characteristic values, or scored, for a particular group.

Statistical Significance

The conclusion that the measured relationship is not simply due to chance.

Effect

The difference in the dependent variable that is due to the changes in the independent variable.

Range

The difference obtained when you subtract the smallest score from the largest, the simplest measure of variability.

Population

The entire set of relevant people or animals.

Normal Distribution

The familiar bell-shaped curve, in which most values fall in the mid range of the scale and scores are increasingly less frequent as they taper off symmetrically toward the extremes.

Standard Deviation

The kind of "average variability" in a set of measurements.

Double-Blind Design

The participant is "blind" to (unaware of) the predictions of the study (and so cannot consciously or unconsciously produce the predicted results), and the experimenter is "blind" to the condition assigned to the participant (and so experimenter expectancy effects cannot produce the predicted results).

Percentile Rank

The percentage of data that have values at or below a particular value.

Inferential Statistics

The results of tests that reveal whether differences or patterns in measurements reflect true differences or patterns versus just chance variations.

Scientific Method

The scientific method involves specifying a problem, systematically observing events, forming a hypothesis of the relation between variables, collecting new observations to test the hypothesis, such as evidence to formulate and support a theory, and finally testing the theory.

Median

The score that is the midpoint of the set of values; half the values fall above the median, and half fall below the median.

Correlational Research

The statistics of the relationships between different variables or data. It is considered a normalized measure of covariance usually.

Random Assignment

The technique of assigning participants randomly, that is, by chance, to the experimental and the control groups, so that no biases can sneak into the composition of the groups.

Mode

The value that appears most frequently in the set of data.

Pseudopsychology

Theories or statements that at first glance look like psychology, but are in fact superstition or unsupported opinion pretending to be science.