**An Overview of**

Statistics

Statistics

What is statistics?

Why should I study statistics?

How can studying statistics help me?

What's the difference between . . .

Data

Information coming from observations, counts, measurements, or responses.

Statistics

The science of collecting, organizing, analyzing, and interpreting data in order to make decisions.

So data is what you collect and statistics are what you do with it.

Data & Statistics

Population & Sample

Population

the collection of ALL the outcomes, responses, measurements, or counts that are of interest.

Sample

A subset of the population.

Your sample comes from the population. For example, if I were to survey your stats class, the class would be a sample and the population would be all MHS students.

When you collect data from an entire population, it is called a census. But unless the population is small it is almost impossible to obtain. In most studies, the data comes from a sample of the population.

Your Turn . . .

The administration at Mason High School conducts weekly surveys of approximately 50 students to determine the average numbers of hours students spend doing homework.

Identify the population.

Identify the sample.

How'd you do?

The population consists of all the students at Mason High school, while the sample is the 50 students surveyed each week.

What's the difference between . . .

Parameters & Statistics

Parameter

a numerical description of a population characteristic.

Statistic

a numerical description of a sample characteristic.

They're both numerical descriptions, but describe different things.

Notice the alliteration:

Population Parameter

Sample Statistic

Your Turn . . .

Describe whether the numerical value describes a population parameter or a sample statistic.

1. The average salary for 10 starting quarterbacks in the NFL is $2.8 million.

2. As of January 2007, 44% of the governors of the 50 states in the U.S. are Republicans

3. Last year the average math scores for all graduates on the ACT was 21.1

How'd you do?

1. This is a sample statistic because is came from a sample of 10 quarterbacks, not all of them.

2. This is a population parameter, because it was determined by looking at ALL 50 states.

3. This is a population parameter, because it is the average for all graduates.

Mr. Mays is a big time Browns fan.

Descriptive & Inferential Statistics

Descriptive Statistics

Statistics that organize, summarize, or display data.

Inferential Statistics

When you use a sample to draw conclusions about a population.

Charts, averages, graphs are all descriptive stats, when you use these descriptive statisitcs to draw conclusions you are making inferential statistics.

Your Turn . . .

Use the graph to describe some descriptive statistics and then create an inferential statistic.

How'd you do?

Some descriptive statistics include:

There were about 250 million video game units sold in 2004.

There were about 50% less serous violent crimes by youth in 2005 compared to 1996.

Some inferential statistics include:

The sale of video games does not appear increase violence in young people.

Qualitative & Quantitative

Qualitative Data

Consists of attributes, labels, and nonnumerical data.

Quantitative Data

Consists of numerical measurements or counts.

If is describes a characteristic then it is most likely Qualitative and if it measures or counts something it is most likely Quantitative.

Your Turn . . .

Below are a number of examples. Are they QUANTITATIVE or QUALITATIVE data?

1. The make and model of a car.

2. The price of a used video game.

3. The daily high temperatures for the month of July.

4. A person's hair style.

5. Your telephone number.

7. The number on a soccer player's jersey.

8. Responses to an opinion poll.

6. The length of songs on your ipod.

Qualitative - No Numbers

Quantitative

Quantitative

Qualitative - No numbers

Mr. Mays is a big Star Wars nerd too.

Qualitative - No numbers

Qualitative - Even though these are numbers, they identify the player. The number on a jersey is not measured or counted.

Quantitative - The time is measured.

Qualitative - Even though it is a number, it identifies you. A phone number is not measured or counted.

It takes a little while for the video to begin. Hang in there and don't skip ahead.