# Statistic ```Unit 1
Section 1.1
1-1: An Overview of Statistics
What is Statistics?
 Statistics
– the science of collecting,
organizing, analyzing, and interpreting
data in order to make decisions.
 Data
– information coming from
observations, counts, measurements,
or responses.
Section 1.1
Why study Statistics?
 Provides
us the ability to read and
understand various statistical studies.
 Provides
us the ability to perform research
and appropriately use data.
 Provides
us the ability to become a better
consumer and citizen.
Section 1.1
 What
are the branches of statistics?
 What
is data?
 How
are samples selected?
Section 1.1
Data Sets
There are two types of data sets we will
utilize when studying statistics:
populations and samples
 Population
– collection of ALL outcomes,
responses, measurements, or counts
that are of interest.
 Sample
– a subset (or part) of a
population
Section 1.1
Population vs. Sample
Students at Eastern High School
Students in
Mr. R’s
Prob/Stat
Class
Section 1.1
Example 1:
Identify the population and the sample.
The US Department of Energy conducts
weekly surveys of approximately 800 gasoline
stations to determine the average price of
gasoline. On December 10, 2012, the
average price of gasoline was \$3.35 per
gallon.
Section 1.1
Parameter vs. Statistic
Parameter
– a numerical description of a
population characteristic.
Statistic
– a numerical description of a
sample characteristic.
Section 1.1
Example 2:
Determine if each numerical value describes
a parameter or a statistic.
A recent survey of approximately 400,000
employers reported that the average starting salary
for marketing majors is \$53,400.

The freshman class at a university has an average
SAT math score of 514.

In a random check of 400 retail stores, the Food
and Drug Administration found that 34% of the
stores were not storing fish at the proper
temperature.

Section 1.1
Branches of Statistics
Descriptive
Statistics – the branch of
statistics that involves the
organization, summarization, and
display of data.
Inferential
Statistics – the branch of
statistics that involves using a sample
to draw conclusions about a
population.
Inferential
statistics often uses probability.
Section 1.1
Example 3:
Determine which part of the study
represents descriptive statistics. What can you
infer from the study?

A large sample of men, aged 48, was studied
for 18 years. For unmarried men,
approximately 70% were alive at the age
of 65. For married men, 90% were alive at
the age of 65.
Section 1.1
Descriptive vs. Inferential
Descriptive
Inferential
Student test scores in this
class
Student test scores for all
students in the next 10 years
Memory spans of 30 subjects Memory spans for normal