Descriptive statistics or inferential statistics?

Students in my statistics class are, on average, 23 years old.

Descriptive statistics because it describes sets of actual observations.

Descriptive statistics or inferential statistics?

The population of the world exceeds 7 billions (that is, 7,000,000,000 or 1 million multiplied by 7000)

Inferential statistics because it generalizes beyond sets of actual observations.

Descriptive statistics or inferential statistics?

Either four or eight years have been the most frequent terms of office actually served by U.S. presidents.

Descriptive statistics because it describes sets of actual observations.

Descriptive statistics or inferential statistics?

Sixty-four percent of all college students favor right-to-abortion laws.

Inferential statistics because it generalizes beyond sets of actual observations.

Population

Any complete collection of observations or potential observations.

Sample

Any smaller collection of actual observations from a population.

Random Sampling

A procedure designed to ensure that each potential observation in the population has an equal chance of being selected in a survey.

Random Assignment

A procedure designed to ensure that each person has an equal chance of being assigned to any group in an experiment.

Is this term associated primarily with a survey or an experiment?

Random Assignment

Experiment

Is this term associated primarily with a survey or an experiment?

Representative

Survey

Is this term associated primarily with a survey or an experiment?

Generalization to the population

Survey

Is this term associated primarily with a survey or an experiment?

Control group

Experiment

Is this term associated primarily with a survey or an experiment?

Real difference

Experiment

Is this term associated primarily with a survey or an experiment?

Random selection

Survey

Is this term associated primarily with a survey or an experiment?

Convenience sample

Experiment

Is this term associated primarily with a survey or an experiment?

volunteers

Experiment

Data

A collection of actual observations or scores in a survey or an experiment.

Qualitative Data

A set of observations where any single observation is a word, letter, or numerical code that represents a class or category.

Yes/No

Y/N

0/1

Ranked Data

A set of observations where any single observation is a number that indicates relative standing.

1st, 2nd…

Quantitative Data

A set of observations where any single observation is a number that represents an amount or a count.

Is it qualitative, ranked or quantitative?

ethnic group

qualitative because it’s a word representing a class or category

Is it qualitative, ranked or quantitative?

age

quantitative because it’s a number representing an amount or a count.

Is it qualitative, ranked or quantitative?

family size

quantitative because it’s a number representing an amount or a count.

Is it qualitative, ranked or quantitative?

academic major

qualitative because it’s a word representing a class or category

Is it qualitative, ranked or quantitative?

sexual preference

qualitative because it’s a word representing a class or category

Is it qualitative, ranked or quantitative?

IQ score

quantitative because it’s a number representing an amount or a count.

Is it qualitative, ranked or quantitative?

net worth (dollars)

quantitative because it’s a number representing an amount or a count.

Is it qualitative, ranked or quantitative?

third-place finish

ranked because it’s a number representing relative standing

Is it qualitative, ranked or quantitative?

gender

qualitative because it’s a word representing a class or category

Is it qualitative, ranked or quantitative?

temperature

quantitative because it’s a number representing an amount or a count.

Level of Measurement

Specifies the extent to which a number (or word or letter) actually represents some attribute and, therefore, has implications for the appropriateness of various arithmetic operations and statistical procedures.

Nominal Measurement

Words, letters, or numerical codes of qualitative data that reflect differences in kind based on classification.

Ordinal Measurement

Relative standing of ranked data that reflects differences in degree based on order.

Interval/Ratio Measurement

Amounts or counts of quantitative data that reflect differences in degree based on equal intervals and a true zero.

Indicate the level of measurement attained by the following sets of observations or data. When appropriate, indicate that measurement is only approximately interval.

height

interval/ratio

Indicate the level of measurement attained by the following sets of observations or data. When appropriate, indicate that measurement is only approximately interval.

religious affiliation

nominal

Indicate the level of measurement attained by the following sets of observations or data. When appropriate, indicate that measurement is only approximately interval.

score for psychopathic tendency

Approximately interval

years of education

interval/ratio

military rank

ordinal

vocational goal (objectif professionnel)

nominal

GPA

Approximately interval

marital status

nominal

Variable

A characteristic or property that can take on different value.

Constant

A characteristic or property that can take on only one value.

Discrete Variable

A variable that consists of isolated numbers separated by gaps.

Continuous Variable

A variable that consists of numbers whose values, at least in theory, have no restrictions.

Approximate Numbers

Numbers that are rounded off, as is always the case with values for continuous variables.

Indicate whether this quantitative observation is discrete or continuous.

litter of mice (une portée de souris)

discrete

Indicate whether this quantitative observation is discrete or continuous.

cooking time for pasta

continuous

Indicate whether this quantitative observation is discrete or continuous.

parole violations by convicted felons

discrete

Indicate whether this quantitative observation is discrete or continuous.

IQ

continuous

Indicate whether this quantitative observation is discrete or continuous.

age

continuous

Indicate whether this quantitative observation is discrete or continuous.

population of your hometown

discrete

Indicate whether this quantitative observation is discrete or continuous.

speed of a jetliner

continuous

Experiment

A study in which the investigator decides who receives the special treatment.

Independent Variable

The treatment manipulated by the investigator in an experiment.

Dependent Variable

A variable that is believed to have been influenced by the independent variable.

Observational Study

A study that focuses on detecting relationships between variables not manipulated by the investigator.

Confounding Variable

An uncontrolled variable that compromises the interpretation of a study.

Is it an experiment or an observational study? If it is an experiment, identify the independent variable and note any possible confounding variables.

years of education and annual income

Observational study

Is it an experiment or an observational study? If it is an experiment, identify the independent variable and note any possible confounding variables.

prescribed hours of sleep deprivation and subsequent amount of REM (dream) sleep

Experiment

Independent variable: prescribed hours of sleep deprivation)

Is it an experiment or an observational study? If it is an experiment, identify the independent variable and note any possible confounding variables.

weight loss among obese males who choose to participate either in a weight-loss program or a self-esteem enhancement program

Experiment

Independent variable: two programs;

Possible confounding variable: self-selection of program

estimated study hours and subsequent test score

Observational study

recidivism among substance abusers assigned randomly to different rehabilitation programs

Experiment

Independent variable: different rehabilitation programs

subsequent GPAs of college applicants who, as the result of a housing lottery, live either on campus or off campus

Experiment

Independent variable: on campus or off campus