Glossary Items Starting with "E"

 
ecological validity
Experiments achieve ecological validity when they reproduce accurately real-life situations, thus allowing easy generalization of their findings. See external validity.


effect size
An index of the size of the statistical difference between groups that is expressed in standard deviation units.


effective range
Characteristic of any dependent measure; the range over which the dependent measure accurately reflects the level of the dependent variable.


electronic mail
A mechanism for sending messages via the Internet to anyone that has an electronic mail address.


E-mail
See electronic mail.


empirical
Based on observed data. For example, a relationship between variables is empirically established if it has been observed to occur.


empiricism
System of knowing that is based solely on observation of the events.


enumerative data
Synonymous with nominal data.


equal intervals
A characteristic of the abstract number system in which the differences between units are the same anywhere on the scale.


equipment subsection
See apparatus subsection.


error bar
An addition made to either histograms or frequency polygons that indicates the size of the standard error of the mean.


error term
Generic term used in many different statistics; it provides a basis for comparing observed differences between groups. The error term is usually based on a measure of the variability of scores within each group.


error variance
A function of the variability of scores within groups.


ethical checks
A series of questions that a researcher must ask about the research and the specific procedures included to safeguard participants.


evaluative biases of language
Language has a tendency to blend description and evaluation, which can distort the perceptions of objective behavior. 


ex-post-facto design
Nonexperimental research design in which the current situation of the participant is observed and related to previous events. Because there are no manipulations of variables, confounding variables cannot be controlled and alternative hypotheses cannot be ruled out. Therefore, it is a weak design and causal inferences cannot be drawn from it.


ex-post-facto fallacy
Error in reasoning in which one assumes that the observed relationship between current events and some historical events represents a causal relationship.


ex-post-facto reasoning
See ex-post-facto fallacy.


ex-post-facto study
See ex-post-facto design.


exact replication
Repeating a study by using exactly the same procedure used in the original study. See also replication.


experiment
High-constraint research procedure in which participants are randomly assigned to two or more conditions and compared on a dependent measure. Experimental designs provide adequate control over virtually all possible confounding variables.


experimental analysis of behavior
Procedures for the controlled study of single individuals or small groups, which are based on B. F. Skinner's operant conditioning concepts.


experimental design
In experimental design, participants are assigned to groups or conditions without bias, such as with random assignment, and all appropriate control procedures are used.


experimental group
Group of participants assigned to one or more conditions defined by a specified level of the independent variable. Contrasted with a control group.


experimental level of constraint
Research in which two or more groups or conditions are compared on at least one dependent measure. Experimental research provides adequate controls for most confounding variables and, therefore, allows the researcher to draw causal inferences.


experimental research
See experimental level of constraint.


experimental variance
Variability among the group means in a research study.


experimentation
Process by which a researcher studies the relationship between independent and dependent variables by systematically manipulating the independent variable and observing the effects of the independent variable on the dependent variable.


experimenter bias
Any effect that the expectations of the researcher might have on the measurement and recording of the dependent variable. Uncontrolled experimenter bias threatens the validity of research.


experimenter effects
Any behavior of a researcher that might affect the behavior of participants or the measurement of dependent variables. Experimenter expectancies can create powerful experimenter effects.


experimenter expectancies
Expectations of the researcher about the relationship between the variables being studied. Experimenter expectancies may affect the accuracy of the observations, especially when judgments are required.


experimenter reactivity
Any action by the researcher other than the manipulation of the independent variable that tends to influence participants' responses. A type of experimenter bias.


exploratory research
Low-constraint research designed to investigate feasibility and to generate, rather than test, hypotheses.


external validity
Extent to which the results of a study accurately indicate the true nature of a relationship between variables. If a study has external validity, the results are said to be generalizeable.


extraneous variable
Any variable other than the independent variable that might affect the dependent measure. Extraneous variables are potentially confounding and must be controlled.


extraneous variance
Variability in scores on the dependent measure that can be accounted for by the effects of extraneous variables.