# Chapter 1: Introduction to Statistics

Data
Consists of information coming from observations, counts, measurement, or responses.

Data example
” People who eat three daily servings of whole grains have been shown to reduce their risk of …stroke by 37%”

Statistics
The science of collecting, organizing, analyzing and interpreting data in order to make decisions.

Population
The collection of all outcomes, responses, measurements, or counts that are of interest.

Sample
A subset of the population

Population example
consists of the responses of all adults in the U.S.

Sample example
Consists of the responses of the 1708 adults in the U.S. in the survey.

Subset example
the sample is a subset of the responses of all adults in the U.S.

Data set example
consists of 939 yes’s and 769 no’s

Parameter
A number that describes a population characteristic

Parameter example
Average age of all people in the United States

Statistic
A number that describes a sample characteristic

Statistic example
Average age of people from a sample of three states

A recent survey of a sample of MBAs reported that the average salary for an MBA is more than \$82,000.
(decide whether the numerical value describes a population parameter or a sample statistic)
Sample statistic (the average of \$82,000 is based on a subset of the population)

Starting salaries for the 667 MBA graduates from the University of Chicago Graduate School of Business increased 85% from the previous year.
(decide whether the numerical value describes a population parameter or a sample statistic)
Population parameter (the percent increase of
8.5% is based on all 667 graduates’ starting
salaries)

Descriptive Statistics
Involves organizing, summarizing, and displaying data.

Tables, charts, averages
Descriptive statistic examples

Inferential Statistics
Involves using sample data to draw conclusions about a population.

Descriptive example
“For unmarried men, approximately 70% were alive at age 65” and “For married men, 90% were alive at 65”