Chapter 1: Introduction to Statistics

60 vocabulary flashcards covering key statistics concepts from Chapter 1 notes.

Population

The entire group of individuals of interest for a research question.

Sample

A smaller, manageable group drawn from the population, intended to represent it.

Population parameter

A numerical value that describes a population.

Sample statistic

A numerical value that describes a sample.

Sampling error

The discrepancy between a sample statistic and the population parameter it estimates.

Margin of error

The sampling error range reported in polls, indicating how much sample results may differ from the population.

Descriptive statistics

Procedures that organize, summarize, and simplify data (e.g., graphs, averages).

Inferential statistics

Procedures that use sample data to make general statements about populations.

Data

Measurements or observations collected in a study; plural of datum.

Datum

A single measurement or observation; a score.

Data set

A collection of scores or measurements.

Parameter

A population characteristic described by a numerical value.

Statistic

A sample characteristic described by a numerical value.

Correlational method

A data-structure method that measures two variables for each individual to assess relationships.

Experimental method

A data-structure method involving manipulation of an independent variable and measurement of a dependent variable to test causation.

Nonexperimental research

Studies that compare groups without true manipulation; cannot prove causation.

Pre–post study

A nonexperimental design comparing a variable before and after a treatment, without time control.

Independent variable

The manipulated variable in an experiment that defines the treatment conditions.

Dependent variable

The variable measured to assess the effect of the treatment.

Treatment condition

Levels of the independent variable used in an experiment.

Control condition

Baseline condition used for comparison with the treatment condition.

Experimental group

Participants exposed to the treatment.

Control group

Participants not exposed to the treatment (or given a placebo).

Random assignment

Assigning participants to groups by chance to create equivalent groups.

Matching

Pairing participants across groups to ensure equivalent groups or environments.

Confounded

A situation where more than one variable could explain results, making causal inference unclear.

Quasi-independent variable

A nonmanipulated variable used to define groups in nonexperimental studies.

Environmental variables

External factors like lighting, time of day, and weather that may influence results.

Data structure

The way data are organized: two variables per individual (correlational) or groups of scores (experimental/nonexperimental).

Scatter plot

A graph showing the relationship between two variables with a point for each individual.

Correlation

A statistic describing the relationship between two variables.

Causation

A cause-and-effect relationship established through experimentation.

Constructs

Internal attributes (e.g., intelligence, hunger) that cannot be directly observed.

Operational definition

Defines a construct by the set of observable procedures used to measure it.

Hypothetical construct

Another term for constructs; internal attributes used to explain behavior.

Discreet variable

A variable with separate, indivisible categories (often whole numbers).

Continuous variable

A variable that can take an infinite number of values and be divided into fractional parts.

Real limits

The boundaries between adjacent scores on a continuous scale.

Nominal scale

Categories that have names but no inherent order or magnitude.

Ordinal scale

Categories with names that are ordered; magnitude/distance is not necessarily equal.

Interval scale

Ordered categories with equal intervals; zero is arbitrary.

Ratio scale

Interval scale with a meaningful absolute zero; allows ratios.

Scale of measurement

Classification scheme (nominal, ordinal, interval, ratio) used to measure a variable.

X

Scores for a variable (the first measurement for each observation).

Y

Scores for a second variable when two variables are measured.

N

Number of scores in a population.

n

Number of scores in a sample.

Summation

The operation of adding a set of numbers; represented by the sigma symbol (o) in the text.

oX

The sum of X values.

oXY

The sum of the products XY for all observations.

oX²

The sum of squared X values.

(oX)²

The square of the sum of X values.

o(X – 1)

The sum of (X – 1) across observations.

o(X – 1)²

The sum of squared (X – 1) values.

Order of mathematical operations

Sequence: parentheses, exponents, multiplication/division, summation, then addition/subtraction.

Mean

The average; a common descriptive statistic.

Median

The middle value in a data set.

Mode

The most frequently occurring value in a data set.

Proportion

A part of a whole expressed as a fraction or percentage.

Corresponding statistic and parameter

Every population parameter has a corresponding sample statistic used for inference.