Unit 1
Sections 1-1 & 1-2
1-1: Introduction
What is Statistics?
 Statistics
– the science of conducting
studies to collect, organize,
summarize, analyze, and draw
conclusions.
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
Questions to think about this chapter…
 What
are the branches of statistics?
 What
is data?
 How
are samples selected?
1-2: Descriptive and Inferential
Statistics

Variable – a characteristic or attribute that can
assume different values.

Data – the values (either measurements or
observations) that variables can assume.

Random Variables – variables that are
determined by chance.

Data Set – a collection of data. Each value
within the data set is called a data value
or a datum.
Section 1-2
 The
body of knowledge of statistics is
sometimes divided into two main areas:
 Descriptive
Statistics – consists of the
collection, organization, summarization, and
presentation of data.
 Inferential
Statistics – consists of generalizing
from samples to populations, performing
estimations and hypothesis test, determining
relationships among variables, and making
predictions.
Section 1-2

Probability – the chance of an event
occurring.

Population – all subjects (human or otherwise)
that are being studied.

Sample – a group of subjects selected from a
population.

Hypothesis Testing – decision making process
for evaluating claims about a population,
based on information obtained from samples.

Correlation – (linear) relationship between two
variables.
Section 1-2
When do we use inferential statistics?
For example, if we want to test whether Bayer aspirin
is better than Tylenol at relieving pain, we could not
give these drugs to everyone in the population.
It’s not practical since the general population is so
large. Instead we might give it to a couple of
hundred people and see which one works better
with them.
With inferential statistics we can infer that what was
true for a few hundred people is also true for a very
large population of hundreds of thousands of
people.
Section 1-2
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
adults
Section 1-2
Assignment:
 Turn
to page 2 in your textbook.
 Read
 After
each of the six bulleted statistics.
you have read each one, determine
if the statistic is descriptive or inferential.
Homework
 Read
and take notes on Section 1-3
 Pages
 Answer
6 – 9 in the text.
questions #1 – 7 on Pg. 9