Section 1.1

Getting Started

HAWKES LEARNING SYSTEMS

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Copyright © 2008 by Hawkes Learning

Systems/Quant Systems, Inc.

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• Statistics is the science of gathering, describing, and analyzing data.

• Statistics is the numerical description of sample data.

Definitions:

Introduction to Statistics

1.1 Getting Started

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• Data – information, in particular, information prepared for a study.

• Population – a particular group of interest.

• Parameter – a numerical description of a particular population characteristic.

• Census – when data is collected from every member of the population.

Definitions:

Introduction to Statistics

1.1 Getting Started

HAWKES LEARNING SYSTEMS

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• Sample – a subset of the population from which data is collected.

• Sample Statistic – a numerical description of a particular sample characteristic.

Definitions:

Introduction to Statistics

1.1 Getting Started

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Population Sample

Whole group Part of the group

Group I want to know about

Group I do know about

Characteristics are called parameters

Characteristics are called statistics

Parameters are generally unknown

Statistics are always known

Parameter is fixed Statistics change with the sample

Introduction to Statistics

1.1 Getting Started

HAWKES LEARNING SYSTEMS

math courseware specialists

• In a survey, 359 college students were asked if they had tried Vanilla Coke. 83 said yes.

Population = all college students

Sample = 359 college students

• A survey of 1125 households in the U.S. found that 65% subscribe to digital cable.

Population = all U.S. households

Sample = 1125 households

Identify the population and the sample.

Introduction to Statistics

1.1 Getting Started

HAWKES LEARNING SYSTEMS

math courseware specialists

Introduction to Statistics

1.1 Getting Started

HAWKES LEARNING SYSTEMS

math courseware specialists

• The average grade on Test 1 in Ms. Shirley’s statistics class is an 87.

Parameter

• The average Math score for all high school graduates on the SAT was a 519.

Parameter

• In a survey of 135 college students, 52% of them said they plan to attend graduate school.

Statistic

Is the numerical value a parameter or a statistic?

• Identify the population and sample.

Population = all families of the students at the school

Sample = 195 families• Does the value “76%” represent a parameter or

a statistic?Statistic

The principal of a large K-12 school is considering adopting a dress code for the upcoming school year. Before going to the school board, he wants to know the percentage of parents who would favor a dress code. He randomly chooses 15 families from each grade to interview. Out of the 195 families surveyed, 76% favor a dress code.

Introduction to Statistics

1.1 Getting Started

HAWKES LEARNING SYSTEMS

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• Descriptive statistics – gathers, sorts, summarizes and displays the data; “just the facts”.

• Inferential statistics – uses descriptive statistics to estimate population parameters; an educated guess about the population based on the facts.

Branches of Statistics:

Introduction to Statistics

1.1 Getting Started

HAWKES LEARNING SYSTEMS

math courseware specialists

Introduction to Statistics

1.1 Getting Started

HAWKES LEARNING SYSTEMS

math courseware specialists

In a survey of 100 students, 83.2% of students are happy with the food in the cafeteria.

Identify the descriptive statistic(s). What inferences can be made?

Descriptive statistic: 83.2% of the 100 students surveyed are happy with the food in the cafeteria.

Possible inferences: 83.2% of all students are happy with the food in the cafeteria.