Unit 1Sections 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.

Questions to think about this chapter…

What are the branches of statistics?

What is data?

How are samples selected?

Section 1-1

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.

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 each of the six bulleted statistics.

After you have read each one, determine if the statistic is descriptive or inferential.

Section 1-2

Read and take notes on Section 1-3 Pages 6 – 9 in the text.

Answer questions #1 – 7 on Pg. 9

Homework