1. Warm-Up 9/5 Round the following numbers to the nearest tenth)
Round the following numbers to the nearest hundredth
3) )

2. Concept 1: Sampling Analysis
LEQ:
1) What are the characteristics of a representative sample?
Vocabulary: Sample, Representative Sample, Population

3. Think About This: Journal Entry
How could the people who reported these data know about the eating, sports, and television viewing activities of all 260 million Americans?

4. Data Collection
When you want to get information about a large group or Population, such as the students at your school or all the fish in a lake, it would be very hard to collect data from each and every person/thing in the group. Instead, you can study a small portion of the group, or a sample.
Can you think of some times where you have hear the word sample or population before? Write them down in your notes

5. Vocabulary
Population: A group of people (or objects or events) that you are gathering information about
They can be animals, insects, or even plants
Sample: A number of people, objects, or events chosen from a given population to represent the entire group. It is a smaller portion of your group.

6. Choosing a Sample
There are a few things to consider when choosing a sample. The first is sample size. You need to make sure that you have enough data to be sure your conclusions are accurate.
How much is enough? You decide.
It depends on your population. The larger the amount of people/things in the population, the larger the sample size will need to be.
In general, the larger the sample size, the more representative it is of the population.

7. Choosing a sample continued..
The sample needs to be representative. If it is representative of the entire population, it can be used to make predictions about the entire group.
What makes a sample representative? It needs to closely match the population. In other words, it has to have a similar make up.

8. Each subgroup in the population should be represented in the sample
ie- if there are boys in your population, there should be boys in your sample
Each subgroup should be represented proportionally
ie- if half of your population is girls, half of your sample should be girls

9. Example
Population: You want to know what foods most middle school and high school students like
Non-representative sample:
Only asking members of the boys soccer team
Only asking students at your middle school
Representative sample:
Asking a few people from each middle school and high school
In order for the sample to be representative, it would need to include boys and girls of middle school and high school age, as well as people from different cultures and neighborhoods

10. When your sample is not representative, you get….
Sampling Bias!
Sampling bias is caused by errors in the sampling process. This can prejudice your evaluation findings in some way. The information gathered will not give you an accurate prediction or conclusion of your population.

11. Example Think Pair Share
Mrs. Jones teaches an 8th grade math class in Texas. She wants to find out if 8th graders in Texas prefer cola or juice, so she polls her thirty 8th grade students. She finds out the most of them prefer cola over juice.
population = sample = Is this sample representative?
Is there sampling bias?

12. Mrs. Jones teaches an 8th grade math class in Texas
Mrs. Jones teaches an 8th grade math class in Texas. She wants to find out if 8th graders in Texas prefer cola or juice, so she polls her thirty 8th grade students. She finds out the most of them prefer cola over juice.
population = all Texas 8th graders sample = Mrs. Jones's thirty 8th graders Is this sample representative? No
Since it is not representative, it is a biased sample and cannot be used to make predictions
Yes, there was a sampling bias. Since the complete sample was from the same school and class, it does not represent the total population of Texas 8th graders very well.
It would give us an accurate idea about 8th grade students in her school, but not 8th grade students in all of Texas.

13. Let’s summarize what we have learned!
Make an acrostic poem S T U D Y

14. Ms. Sampson (snaps) So you want gather information about a population
Take a representative sample
Unless you want your data to be biased
Don’t want that!
You can use the sample to make predictions about the whole group.

15. Resources Used
Math on Call
Study Island

16. Practice
Independently complete the worksheet about selecting samples

17. Exit ticket

18. HW
Representative Sample worksheet