Review Question Give an example of a statistic. Eye color, batting average, salary, grades

Discussion In this unit we will be discussing statistics. There are different words used in statistics compared to our normal math words. Can someone give me some “normal” math words? Add, Fraction, Equal to

Discussion Can someone give me some “normal” statistic words? Mean, Population, Sample, Bias Today, we are going to discuss what these new words mean.

Today’s Objective You will be able to define statistical vocabulary. You will be able to make predictions of a large group based on a sample.

Definitions Statistics – collecting, organizing, and interpreting data Population – the entire group that is being studied Sample – part of the population used to collect the data

Definitions Have you ever been walking around a store and someone asks you, “Would you like a sample?” Notice this is just a small piece of the product they want you to buy. This helps me remember that a sample is just a piece of the population.

Example 1 The owner of a mall notices that the food court is losing money. So he decides to gather data to figure out why this is happening. What type of data/statistics would he need to gather? How could this data/statistics help the owner?

Example 1 What would the population of his survey be? What would be an example of a sample of the population?

Example 1 Would a sample of just teenagers give the owner “good” results to his survey? What would a sample look like that would produce “good” results?

Example 1 When a “good” sample is being collected, it is important to make sure that the sample is being collected randomly. What does that mean? How could you collect a random sample for this survey?

Example 2 Over the past few weeks, the students and teachers have been arguing over the particulars of the dress code. So the principal decides to gather data to figure out how everyone feels about the current dress code. What type of data/statistics would the principal need to gather? How could this data/statistics help the principal?

Example 2 What would the population of this survey be? What would be an example of a sample of the population?

Example 2 Would a sample of just 10th grade girls give the owner “good” results to his survey? What would a sample look like that would produce “good” results? How could you collect a random sample for this survey?

Example 3 A survey found that 70% of people in the USA have a Facebook account. What would a sample look like that would produce “good” results for this survey? About how many students out of 125 should have a Facebook account? About how many students out of 450 should have a Facebook account?

What did we learn today? To define statistical vocabulary To make predictions of a large group based on a sample

Review Question What is the difference between a population and a sample? A population is the entire group that is being surveyed while a sample is just a portion of the population.

Discussion Timmy plays Little League Baseball. His dad is the coach of his team. His dad is also the coach of the All-Star team. His dad chooses Timmy and all of his friends for the All-Star team. Is this fair? Why or why not?

Discussion Is this the best way to choose the All-Stars? What would be a better way to choose the team?

Discussion This is clearly unfair. We could say that Timmy’s dad has a bias towards his son and his friends. Notice that this way of picking the team would not produce the best results. The same thing is true in statistics. When you are collecting data you must collect it in a way that is fair to ensure the best results.

Discussion In statistics they don’t use the words fair and unfair. Rather, they use the words unbiased and biased. That is what today’s lesson is about.

Today’s Objective You will be able to define statistical vocabulary. You will be able to make predictions of a large group based on a sample.

Definitions Unbiased Sample – sample that represents an entire population; “fair” Biased Sample – sample that favors one part of a population; “unfair”

Discussion Jimmy is opening a new shoe store for teenagers. So he is doing a survey to figure out what type of shoes he should sell.

Discussion What would an unbiased sample for teenager’s favorite brand of shoes look like? How many people should we survey? What would a biased sample look like?

Example 1 We are collecting data about what cell phone provider people like the best. What would the population be? What would an unbiased sample look like? What would a biased sample look like?

You Try! 1. We are collecting data about who is going to be the homecoming queen. What would the population be? What would an unbiased sample look like? What would a biased sample look like?

You Try! 2. We did a survey to find out what is the most popular store at the mall for teenagers. What would the population be? What would an unbiased sample look like? What would a biased sample look like?

You Try! 3. We asked 100 teenagers about their favorite store with the following breakdown: 50 boys (10 from each age from 13-17) 50 girls (10 from each age from 13-17) a. Does this represent an unbiased or biased sample? Why?

You Try! b. The results from this survey are as follows: 10 – Dicks, 15 – Finish Line, 40 – Hollister, 20 – Forever 21, 15 – Abercrombie Based on these survey results: About how many students out of 350 should choose Finish Line? About how many students out of 750 should choose Hollister?

You Try! 4. Why would someone want to create a survey using a biased sample?

What did we learn today? To define statistical vocabulary To make predictions of a large group based on a sample