statistics
a set of mathematical procedures for organizing, summarizing and interpreting info.
population
set of all individuals of interest in a particular study
sample
set of individuals selected from a population, usually intended to represent the population in a research study
variable
characteristic/condition that changes or has different values for different individuals
data (plural)
measurements/observations
data set
collection of measurements/observations
datum (singular)
single measurement/observation and is commonly called a score/raw score
parameter
a value, usually a numerical value, that describes a population. A parameter is usually derived from measurements of the individuals in the population
statistic
a value, usually a numerical value, that describes a sample. A statistic is usually derived from measurements of the individuals in the sample
Descriptive statistics
statistical procedures used to summarize, organize and simplify data
Inferential statistics
consists of techniques that allow us to study samples and then make generalizations about the populations from which they were selected
sampling error
the discrepancy, or amount of error, that exists between a sample statistic and the corresponding population parameter
correlational method
two different variables are observed to determine whether there is a relationship between them
control condition
Individuals do not receive the experimental treatment. Instead, they either receive no treatment or they receive a neutral, placebo treatment. The purpose of a control condition is to provide a baseline for comparison with the experimental condition.
experimental condition
Individuals that do receive the experimental treatment.
quasi-independent variable
In a nonexperimental study, the "independent variable" that is used to create the different groups of scores
constructs
internal attributes/characteristics that cannot be directly observed but are useful for describing and explaining behavior
operational definition
Identifies a measurement procedure (a set of operations) for measuring an external behavior and uses the resulting measurements as a definition and a measurement of a hypothetical construct. Note that an operational definition has two components: First, i
discrete variable
consists of separate, indivisible categories. NO values can exist b/n 2 neighboring categories.
continuous variable
there are an infinite number of possible values that fall between any two observed values. A continuous variable is divisible into an infinite number of fractional parts.
real limits
the boundaries of intervals for scores that are represented on a continuous number line. The real limit separating two adjacent scores is located exactly halfway between the scores. Each score has two real limits. The upper real limit is the top of the in
nominal scale
consists of a set of categories that have different names. Measurements on a nominal scale label and categorize observations, but do not make any quantitative distinctions between observations.
ordinal scale
consists of a set of categories that are organized in an ordered sequence. Measurements on an ordinal scale rank observations in terms of size/magnitude
interval scale
consists of ordered categories that are all intervals of exactly the same size. Equal differences b/n numbers on scale reflect equal differences in magnitude. However, the zero point on an interval scale is arbitrary and does not indicate a zero amount of
ratio scale
an interval scale with the additional feature of an absolute zero point. With a ratio scale, ratios of numbers do reflect ratios of magnitude.
experimental method
one variable is manipulated while another variable is observed and measured. To establish a cause-and-effect relationship between the two variables, an experiment attempts to control all other variables to prevent them from influencing the results.
independent variable
the variable that is manipulated by the researcher. In behavioral research, the independent variable usually consists of the two or more treatment conditions to which subjects are exposed. The independent variable consists of the antecedent conditions tha
dependent variable
the variable that is observed to assess the effect of the treatment.