Ninth Edition CoverGraziano & Raulin
Research Methods (9th edition)

Glossary Items Starting with "R"

random number generator
A computer function that generates an endless sequence of random numbers.

random order of presentation
This is a way of controlling for carry-over effects in within-subjects designs. Each participant is tested under all conditions, but the order of the conditions is randomly determined for each participant.

random samples
Samples that are drawn using random sampling techniques.

random sampling
Procedure for the selection of participants in which each participant has an equal chance of being selected and the selection of any one participant will not affect the probability of selecting any other participant. In most research, random sampling from the population is not feasible. Instead, researchers rely on sampling from an accessible population.

Any procedure that assigns a value or order in an unpredictable or random way, such as by use of tables of random numbers. Randomization procedures may be used for selecting participants, assigning participants to groups or conditions, or assigning the order in which a participant will experience a number of successive conditions.

randomize within blocks
A control procedure to reduce sequence effects, which involves using a block of one trial from each condition and randomizing participant assignment to these conditions before going on to the next block.

randomized, posttest-only, control-group design
Experimental design in which participants are randomly assigned to two groups, and each group is tested on the dependent variable after the independent variable manipulation.

randomized, pretest-posttest, control-group design
Experimental design in which participants are randomly assigned to two groups, and each participant is tested on the dependent variable both before and after the manipulation of the independent variable.

Distance between the lowest score and the highest score.

ratio scale
Scale of measurement in which the intervals between scores are equal and the zero point on the scale represents none of the quality being measured (a true zero). Examples of ratio scales are height, weight, and frequency of an event.

A way of knowing about the universe that relies on systematic logic and a set of premises from which logical inferences are made.

reactive measure
Any measurement procedure that produces different scores depending on whether participants are aware they are being measured.

records (in computer files)
Each record typically represents all of the data for a single participant or for a group of matched participants.

The listing of a source of information (e.g., research article, book, chapter, etc.) that contributed to a research paper. The APA Publication Manual lists specifications for how to list a reference so that others can quickly find it.

reference list
The listing of a source of information (e.g., research article, book, chapter, etc.) that contributed to a research paper. The Publication Manual of the American Psychological Association lists specifications for how to list a reference so that others can quickly retrieve it for review.

reference section
The section of a research report that follows the substantive sections of the report and lists each of the papers and articles that contributed to the ideas and procedures of the study described in the report.

A mathematical procedure that produces an equation for predicting a variable (the criterion measure) from one or more other variables (the predictor measures). The procedures for determining the regression equation are designed to maximize the accuracy of the prediction. Linear regression equations are usually used, although it is possible to develop non-linear regression equations.

regression equation
The mathematical equation that predicts the value of one variable from one or more other variables.  

regression to the mean
Potential confounding variable that occurs whenever participants are selected because of extreme scores (either very high or very low). When retested on the same or similar variable, the original extreme sample tends to be less extreme on average.

reification of a construct
Incorrectly accepting a construct as a fact.

Any connection between two or more variables. In research, there are many types of relationships, from contingencies to causal relationships.

relative score
See standard score.

Index of the consistency of a measuring instrument in repeatedly providing the same score for a given participant. There are many different types of reliability, each referring to a different aspect of consistency. Types of reliability include interrater reliability, test-retest reliability, and internal consistency reliability.

repeated-measures ANOVA
Statistical procedure to evaluate the mean differences between two or more conditions in which participants are tested under each condition. The repeated-measures ANOVA takes into account the fact that the same participants appear in all conditions.

repeated-measures design
Any research design in which participants are tested more than once. Examples of such designs are pretest-posttest designs, within-subjects designs, and time-series designs.

repeated-measures factorial
Factorial design in which all factors are within-subjects factors. Each participant is tested under every possible combination of conditions in the design.

repeated-measures factorial ANOVA
The statistical procedure for analyzing the results of a factorial study in which all factors are within-subjects factors.

See replication.

To repeat a study with no changes in the procedure (exact replication), small theory driven changes (systematic replication), or changes in the operational definitions of variables (conceptual replication).

representative sample
Sample of participants that adequately reflects the characteristics of the population from which the sample was drawn.

Degree to which a sample is representative of the population from which the sample was drawn.

research data
See data.

research design checklist
An assessment of a research design procedures prior to data collection.

research ethics
Set of guidelines designed to protect human and nonhuman participants from the risks of participating in research.

research hypothesis
Precise and formal statement of a research question. The research hypothesis is constructed by adding operational definitions for each of the variables to the statement of the problem.

research setting
Any characteristics of the situation and/or surroundings in which a research project is carried out. Settings may vary from natural, real-world settings to highly constrained and carefully controlled laboratory settings.

response-inferred organismic variable
A hypothesized internal attribute of an organism that cannot be directly observed but, instead, is inferred on the basis of some observed behavior. Examples are intelligence, anxiety, anger, and love.

response-set bias
Any tendency for participants to distort their responses to a dependent measure.  Response-set biases create measurement errors.

results section
The section of a research report that describes the findings and reports on the statistical analyses of the data.

reversal design (ABA)
Research design often used with single participants, in which the effects of an independent variable on a dependent variable are inferred from observations made first without the independent variable present, then with the independent variable present, and again without the independent variable present. If an effect is noticed both when the independent variable is added and when it is later removed, it is likely that the independent variable is causally related to the dependent measure.

rival hypothesis
Any feasible alternative hypothesis to the causal hypothesis.

A statistical test is said to be robust to violations of the assumptions on which the test is based if the test consistently leads to accurate conclusions despite the assumption violations.

row means
In factorial designs, one factor is usually illustrated as separate rows of data in which each row represents a different level of the factor. A second factor is illustrated as columns of data in which the different columns represent various levels of the second factor. Row means are computed by taking the mean of all participants who appear in a given row regardless of their level on the second factor.