basic concepts, notation, and summation

random variable

property that can take on at least two different values, which are associated w/ a set of probabilities

(e.g., intelligence, height, hair colour)

constants

do not vary and are static values

variables in psychology

indirect representations of phenomena/objects that are inferred, rather than directly calculated

discrete variables

values that are of disjointed categories from one another

- ordered or unordered

(nominal or ordinal scale)

continuous variables

numbers across the continuum of the number line

(interval or ratio scale)

ordered categorical/pseudo-continuous (OC/PC) variables

discrete variables (ordinal) that are treated as continuous (interval or ratio) if values are ordered and have at least 5 categories

distributions

how the values for a random variable distribute over the range of possible values

empirical distributions

consists of real data

- associated with samples

theoretical distributions

defined by mathematicians/statisticians and are abstract or idealized

- associated with populations

census populations

refers to all individuals or objects of interest that a research aims to generalize about

statistical populations

refers to entire set of possible outcomes on a variable of interest and their associated probabilities + frequencies

- abstract and mathematically defined

sample

subset of values, scores, or measurements taken from a statistical population

population parameters

single-value quantitative summaries that describe characteristics of a theoretical distribution

sample statistics

single-value quantitative summaries that describe characteristics of an empirical distribution

data analysis

process in which we simply summarize or describe an empirical distribution (sample)

statistical inference

process of using sample statistics to estimate the values of population parameters

notation

ways in which we represent aspects of data, such as variables and scores/measurements/values

general case notation (i)

general index of scores used to reference ANY given score

sample size (N)

number of values recorded for a random variable (participants in a study)