- 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.

- similarity-uniqueness paradox
- 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, s
*ingle-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*.

- spread
- Synonymous with
variability.

- spreadsheet
- 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.