﻿ Glossary Items Starting with "S"

Graziano & Raulin
Research Methods (8th edition)

## Glossary Items Starting with "S"

sample
Any subset drawn from a population. Researchers work with samples of participants and draw inferences about the larger population.

sample statistic
Descriptive index of some characteristic of the sample of participants. Population parameters are estimated on the basis of sample statistics.

sampling
Process of drawing a sample from a population. Many sampling techniques are available, including random sampling, stratified random sampling, and various nonrandom sampling techniques.

sampling error
Chance variation among different samples drawn from the same population.

sampling frame
In survey research, a sampling frame is a list of all participants from an available population. The sampling frame is a subset of a larger population from which a representative sample is drawn.

scale attenuation effects
Any aspect of the measuring instrument that limits the ability of the instrument to make discriminations at the top of the scale (ceiling effects) or the bottom of the scale (floor effects).

scales of measurement
Characteristics of the scores produced by a particular measurement instrument. Scales of measurement vary on how closely scores match the real number system. There are four generally recognized scales of measurement: nominal, ordinal, interval, and ratio scales.

scatter plot
Graphic technique that illustrates the relationship between two or more variables. In a two-variable situation, the scatter plot is constructed by labeling the x-axis with one of the variables and the y-axis with the other variable and plotting each participant's pair of scores in the xy coordinate system. Scatter plots illustrate the type, direction, and strength of relationships.

science
Way of knowing that combines rationalism and empiricism to form a system that places great demands on procedures, data, and theories.

Scientific Revolution
Period of time (15th through the 17th centuries) in which scientific methods and applications became independent from theology and developed rapidly into a generally recognized way of understanding nature.

scientific research
Research based on a combination of rationalism and empiricism.

scientist
Anyone who utilizes the methods of science to study a phenomenon.

scientist-practitioner model
A model for the training of clinical psychologists that teaches both research and clinical skills in an integrated manner. The rationale is that clinical psychology is an emerging discipline in which practitioners need to learn from new research and contribute to the knowledge base by conducting their own research. This approach is also known as the Boulder model, named after the conference held in Boulder, Colorado in which these principles were endorsed.

score data
Data produced by interval or ratio scales of measurement.

secondary analyses
In the analysis of research data, secondary analyses look at questions that are not directly stated in the original research hypothesis but that may be relevant to understanding some of the primary analyses.

secondary sources
Sources of information in the library that provide reviews of entire areas of research.

selection
A potential confounding variable that involves any process that may create groups not equivalent at the beginning of the study.

sequence effects
The confounding effects on the performance in later conditions due to having experienced previous conditions.

serendipity
Unanticipated,  seemingly "lucky" scientific discoveries. Alert scientists seize upon and develop unanticipated observations that others might have ignored.

The tendency to simplify comparisons between objects by seeing them as either similar to one another or different from one another, when in reality they are probably both.

simple random sampling
See random sampling.

single-blind procedure
Research procedure in which the researcher is unaware of the condition to which each participant is assigned. The purpose of the single-blind procedure is to minimize measurement reactivity.

single-group, posttest-only design
Nonexperimental research design in which the researcher manipulates the independent variable and then takes a post-manipulation measure on the dependent variable. The difference between this design and an ex post facto design is the manipulation of the independent variable.

single-group, pretest-posttest design
Nonexperimental design in which a group of participants is measured on a dependent variable, the independent variable is manipulated, and a second measure on the dependent variable is taken. The design allows comparison between pretest and posttest scores but, because no control group exists, confounding variables are not adequately controlled.

single-subject clinical replication
A specialized form of replication for single-subject designs that is used primarily in clinical settings.

single-subject experimental designs
Research designs that seek information sufficient to draw causal inferences. Single-subject designs have some form of built-in control to compensate for the fact that no control group exists. Typical examples of single-subject designs are the reversal design, single-subject, randomized time-series design, and multiple baseline design.

single-subject, randomized, time-series design
Designs frequently used in naturalistic settings in which multiple measures on the dependent variable are taken both before and after some manipulation of an independent variable. This design provides partial control of confounding variables by allowing the researcher to see patterns in the movement of the dependent variable over time and specific changes in the dependent measure that appear to be a function of the manipulation of the independent variable.

single-subject direct replication
Repeating a single-subject experiment with the same participant or other participants with the same target behavior in order to establish the effectiveness and reliability of the procedure. Direct replication does not establish its generalizability to other persons, conditions, or target behaviors. For that, single-subject systematic replication is needed.

single-subject systematic replication
The carefully planned and executed testing for generalization of a procedure to other conditions, persons, and target behaviors after direct replication has established the effectiveness and reliability of the procedure for one or more participants with the same target behavior.

single-variable, between-subjects design
Research designs that include only one independent variable and in which participants are randomly and independently assigned to groups.

single-variable design
Research designs that include just one independent variable.

skeptic
One who practices skepticism

skepticism
Unwillingness to accept information as valid knowledge without some documentation to confirm it. Skepticism is one of the strongest tools available to scientists.

skewed distribution
Any distribution of scores in which scores bunch up at the end of the distribution. Skewed distributions are often contrasted with symmetric distributions.

skewed negatively
Distribution in which scores are concentrated near the top of the scale with few scores near the lower end of the scale.

skewed positively
Distribution in which scores are concentrated near the bottom of the scale with few scores near the top of the scale.

social desirability
Response set in which participants tend to say what they believe is expected of them (i.e., they tend to present themselves in a socially desirable light).

Solomon's four-group design
Sophisticated experimental design that combines the randomized, posttest-only, control-group design and the randomized, pretest-posttest, control-group design.

sophisticated empiricism
Indirect observation of facts through mediational constructs and procedures. Sophisticated empiricism does not limit us to our own personal senses for direct observation. For example, we cannot directly see or measure gravity but can infer it from observing falling bodies.

Spearman rank-order correlation
Correlation coefficient that indexes the degree of relationship between two variables, each of which is measured on an ordinal scale.

specific means comparisons
The process of evaluating differences in group performance in a research study with more than two groups to see which groups are statistically different from which other groups. Specific means comparisons can be carried out as either planned comparisons or post hoc tests.

Synonymous with variability.

A mechanism for organizing data in rows and columns. Typically, a data spreadsheet is organized so that each row represents the data for one participant and each column represents the scores on one variable.

SPSS for Windows
A computer package (Statistical Package for the Social Sciences) for statistical data analysis on a Windows-based computer.

standard deviation
An index of variability that is the square root of the variance.

standard error of the differences between means
The denominator in a t-test.

standard error of the mean
The standard deviation of the sample divided by the square root of the sample size. The standard error of the mean is the standard deviation of a distribution of means for a given sample size drawn from a specified population.

standard score
A score that gives the relative standing in a distribution. It is computed by subtracting the distribution mean from the score then dividing that value by the standard deviation from the distribution.

statement of the problem
First major refinement of initial research ideas in which a clear statement of the expected relationship between conceptual variables is made. The statement of the problem is refined into one or more research hypotheses by specifying the operational definitions of each variable.

Statistica
Computer package for statistical data analysis.

Statistical Analysis System (SAS)
Computer package for statistical data analysis.

statistical hypothesis
Synonymous with null hypothesis.

Statistical Package for the Social Sciences (SPSS)
Computer package for statistical data analysis.

statistical power
See power of a statistical test.

statistical significance
A finding is said to achieve statistical significance if it is unlikely that such a finding would have occurred by chance alone. See statistically significant differences.

statistical symbols
Conventional short-hand used to denote statistical terms. For example, the Greek letter alpha is the statistical symbol for the level of Type I error.

statistical validity
Accuracy of conclusions drawn from a statistical test. To enhance statistical validity, one must meet critical assumptions and requirements of a statistical procedure.

statistically equal
Groups are statistically equal when the small differences that do exist are the result of sampling error.

statistically significant correlation
A correlation large enough that one would conclude that there is a nonzero relationship between the variables.

statistically significant differences
A difference between two or more means large enough that it is unlikely to be a chance occurrence.

statistics
Mathematical procedures used to evaluate the results of a research study. Some statistical procedures describe data (descriptive statistics), whereas others help draw conclusions about data (inferential statistics).

status survey
A simple survey designed to provide a description of the current status of some population characteristic.

Statview
A statistical analysis package for Macintosh computers.

stimulus variable
Any variable that is part of the environment to which an organism reacts. A stimulus variable may be a natural part of the environment and observed by the researcher or may be actively manipulated by the researcher.

strata
Subpopulations within populations from which we draw samples. See stratified random sampling.

stratified random sampling
Variation of the random sampling procedure in which a population is divided in narrow strata along some critical dimension. Participants are then selected randomly from each of the strata in the same proportion that the strata are represented in the population. Stratified random sampling can increase the representativeness of the sample and is used extensively in sophisticated survey research.

structuralism
A philosophical perspective in which scientists seek to identify the structure of the underlying mechanisms that control conscious behavior. This approach was popularized by Wundt. Often contrasted with functionalism.

subject assignment
See participant assignment.

subject effects
Any response by participants in a study that does not represent the way they would normally behave if not under study. Two powerful subject effects are the placebo effect and a participant's response to demand characteristics.

subject selection
See participant selection.

subject variable
Synonymous with organismic variable.

subjective measure
A measure based primarily on participants' uncorroborated opinions, feelings, biases, or judgments. Subjective measures, as contrasted with objective measures, are more prone to distortions due to experimenter effects.

subjects at risk
See participants at risk.

subject's rights
See participants' rights.

subjects subsection
See participants subsection .

subjects term
The individual differences component of the within-groups variability in a repeated-measures ANOVA.

sum of squares
Sum of the squared differences from the mean.

summary statistics
Descriptive statistics that provide, in a single number, some general characteristic of the sample. Typical summary statistics are the mean, median, variance, and standard deviation.

survey
A set of questions posed to a group of participants about their attitudes, beliefs, plans, lifestyles, or any other variable of interest.

survey research
Research that seeks to use survey procedures to identify relationships among the variables being surveyed.

symmetric distribution
Graphical representation of any distribution in which the right half of the distribution is a mirror image of the left half. Symmetric distributions are often contrasted with skewed distributions.

systematic between-groups variance
Variability between groups that is brought about by either the experimental manipulation or by a confounding variable.

systematic influence
The stimulating effects of previous research and theories in providing testable propositions for further study.

systematic replication
Repeating a study with small, theory-based changes in the procedures. Systematic replication is more common than exact replication because it verifies original findings while also expanding knowledge of the phenomena.