Unit 1: Let’s Get Started

Day 2 NotesWhere 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 %)

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

Statistics is…

How are statistics used today?

AdvertisementsMedical StudiesManufacturing

SportsGovernmentManagement

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 GossettStudent’s t-distribution

Guinness brewery in Dublin, IrelandW. Edwards Deming (1950’s and 1960’s)

Used statistics with Japanese manufacturers

Statistics Today

Descriptive or InferentialDescriptive:

Summarizing or displaying data so we can quickly obtain an overviewEasier, 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 dogsEstimating 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 SamplePopulation:

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

Examples:All GHS studentsCitizens of Bowling GreenAll females in America

Population and SampleSample:

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

Random selection of 50 GHS malesRandom selection of 200 Bowling Green citizensRandom survey of 300 females in America

Your turn:

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

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

1

Your turn:

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

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%).

2

Your turn:

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

Hank Aaron hit 755 career home runs.3

Your turn:

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

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

4

Your turn:

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

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

5

Your turn:

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

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.

6

Your turn:

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

Greenwood’s basketball coach wants to know the average height of boys at Greenwood. He randomly selects 50 boys and records their height.

7