# Unit 1: Let’s Get Started - PowerPoint PPT Presentation

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Unit 1: Let’s Get Started. Day 2 Notes Where is this used? Who thought of this? Statistics today…. We see on TV…. 4 out of 5 doctors recommend…. We see on TV…. Obama leads by 3% (+ or – 4 %). Statistics is….

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Unit 1: Let’s Get Started

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## Unit 1: Let’s Get Started

Day 2 Notes

Where is this used? Who thought of this?

Statistics today…

## We see on TV…

4 out of 5 doctors recommend…

## We see on TV…

Obama leads by 3% (+ or – 4 %)

Statistics is…

A way to convert numbers into useful information so that good decisions can be made.

• How are statistics used today?

Manufacturing

Medical Studies

Management

Government

Sports

### Who thought of this stuff?

• The Bible: Moses (3000 + years ago)

• European mathematicians

• Sir William Petty (1532)

• First accounts of deaths in London on a weekly basis

• James Bernoulli (Swiss, 1600’s)

• Probability of a sequence of events

• Thomas Bayes (English, 1700’s)

• Probability concepts

### More Recently….

• 20th century ROCKS for statistics

• William Gossett

• Student’s t-distribution

• Guinness brewery in Dublin, Ireland

• W. Edwards Deming (1950’s and 1960’s)

• Used statistics with Japanese manufacturers

### Statistics Today

• Descriptive or Inferential

• Descriptive:

• Summarizing or displaying data so we can quickly obtain an overview

• Easier, calculator-friendly

• Inferential:

• Making claims or drawing conclusions about a population based upon a sample of data from that population.

### Descriptive or Inferential?

• Comparing the average attention span of GHS students to the average attention span of their dogs

• Estimating the average attention span of GHS students based upon the attention span of those in Mrs. Brittenham’s class

### Some Inferential Statements:

• Based on a recent sample, I am 95 percent certain that the average age of my customers is between 32 and 35 years old.

• The average salary for male employees in a particular job category across the country was higher than the female employees’ salary, based on a random survey.

### Population and Sample

• Population:

• All possible measurements or outcomes that are of interest to us in a particular study

• Examples:

• All GHS students

• Citizens of Bowling Green

• All females in America

### Population and Sample

• Sample:

• A portion of the population that is representative of the population from which it is selected

• Random selection of 50 GHS males

• Random selection of 200 Bowling Green citizens

• Random survey of 300 females in America

• Identify each of the following statistics as either descriptive or inferential.

1

73% of Asian American households in the US own a computer.

• Identify each of the following statistics as either descriptive or inferential.

2

Households with children under the age of 18 are more likely to have access to the Internet (62%) than family households with no children (53%).

• Identify each of the following statistics as either descriptive or inferential.

3

Hank Aaron hit 755 career home runs.

• Identify each of the following statistics as either descriptive or inferential.

4

The average SAT score for incoming freshmen at a local college was 950.

• Identify each of the following statistics as either descriptive or inferential.

5

On a recent poll, 67 percent of Americans had a favorable opinion of the President of the United States.

• In each of the following, identify the population and the sample.

6

A local politician wants to know the proportion of Warren County residents who support her. She takes a list of registered Democrats and randomly selects 1000 to ask if they support her.