1. Common Core Math I Unit 2 One-Variable Statistics

2. Two Main Uses of Statistics
TO DESCRIBE (Data Analysis) TO PREDICT (Statistical Inference)

3. Definitions Data: A collection of information in context.
Population: A set of individuals that we wish to describe and/or make predictions about.
Sample: A subset of the population that data is collected from.
Individual: Member of a population.
Variable: Characteristic recorded about each individual in a data set.

4. Types of Variables
Categorical Variable: A variable that records qualities or characteristics of an individual, such as gender or eye color.
Quantitative Variable: A variable that measures a characteristic of an individual, such as height, weight, or age.
In this unit, we will focus on quantitative data.
When describing categorical vs. quantitative, explain that sometimes numerical data is categorical. Think of quantitative data as “How many?” For example, when classifying a zip code as categorical or quantitative, you would ask, “What is your zip code?” not, “How many….zip code?”

5. What type is it?
Categorical
Quantitative
Go over the Collect student data worksheet and discuss which type of variable each one is.

6. Categorical or Quantitative Data?
birth month
number of siblings
height in inches
average amount of time (in minutes) of your ride to school
number of pets
year & model of the car you drive
age of your youngest parent
predicted letter grade of your last test

7. 1. Brand of vehicle purchased by a customer 2. Price of a CD 3
1. Brand of vehicle purchased by a customer 2. Price of a CD 3. Number of students in a class of 30 who prefer milk chocolate over dark chocolate 4. Phone number of all the students enrolled in school 5. The height of a 1 year old child 6. Number of students in a class of 35 who turn in a term paper before the due date 7. Gender of the next baby born at a particular hospital 8. Amount of fluid (oz) dispensed by a machine used to fill bottles with soda 9. Thickness of the gelatin coating of a Vitamin C capsule 10. Brand of computer purchased by a customer 11. State of birth for someone born in the United States 12. Price of a textbook 13. The zip codes of everyone in this class 14. Actual weight of coffee in a one pound can 15. The length of a rattlesnake

8. Describing Data
Two ways to describe data: 1. Graphically 2. Numerically

9. Describing Data Graphically
Dotplot
Histogram
Boxplot

10. Describing Data Numerically
Measures of Center
mean
median
Measures of Spread
range
interquartile range
standard deviation

11. What is the typical value?
Measures of Center
What is the typical value?
Mean
the average
the sum of a set of data divided by the number of data (do NOT round your answer unless directed to do so)
Median
the middle value, or the mean of the middle 2 values, when the data is arranged in numerical order
think of a “median” in the middle of a highway
Note: Students do NOT need to copy down these definitions at this point – more with these will come later in the unit.

12. How much do values typically vary from the center?
Measures of Spread
How much do values typically vary from the center?
Range
Interquartile Range (IQR)
Standard Deviation

13. Common Core Math I Unit 2 Frequency Tables and Histograms

14. Link Up Frequency Distribution Table Histogram (by hand)
How many links can you put together in one minute?
One student will time another student for 60 seconds. The student being timed will link together as many paper clips as he or she can in 60 seconds, and record this number on his or her paper. The students should then switch roles so the other student can link paper clips.
Collect data and have students record on the board in a frequency distribution table. You may want to ask for the minimum and maximum values so that you can determine intervals.
Show how to make a histogram from this by hand. Make sure that you are not just making a bar graph. The bars should be touching (like the next slide) to show the continuity of the data. Usually the lower value for each interval is marked on the x-axis on the left side of the corresponding “bar”, although you can also use the midpoint of the interval as well. Discuss with students – what is the difference between a bar graph and a histogram? (bars touching; bar graphs used with categorical data & histograms used with quantitative data divided into intervals)

15. Describing Distributions
Shape
Center
Spread
Outliers
In order to describe a distribution, we address the following things: the shape of the distribution, the center or most typical value, how spread out the data is, and if there are outliers, we note them.

16. Shape mound shaped & symmetrical skewed left (extreme low values)
skewed right (extreme high values)
uniform
What shape does our links distribution have?

17. Center
When describing a distribution at first, the center can be “eyeballed.” Remember, you are trying to answer the question: “What is the most typical value?”
When first discussing how to interpret graphs, have students give an eyeball estimate of the center of the distribution. Then formalize with the numerical calculations later on in the unit.
What is the approximate center, or typical value, for the number of links put together in one minute?

18. Spread BE SURE TO STATE EVERYTHING IN CONTEXT Range
Remember, you are trying to answer the question:
“How much do values typically vary from the center?”
BE SURE TO STATE EVERYTHING IN CONTEXT
Again, when first describing distributions, we do not need to go into the numerical calculations of the interquartile range or the standard deviation – just focus on the maximum and minimum values and use the range to describe the distribution of the data.
What was our maximum number of links? Our minimum number? So what is the range?
Do we have any apparent outliers? (What is an outlier? An informal definition is fine – a data value that does not fit the overall pattern.)
Have students write a one to two sentence summary describing the shape, center, spread, and outliers – in context!
For example: The distribution of the number of links a student can put together in one minute is skewed to the right. Students can typically hook up about 35 links in one minute, with a few really dexterous students able to link together 60 or more. The number of links put together varied from 16 to 68.

19. NFL Rushing Statistics
Group activity:
Make a frequency distribution table for your assigned column of data.
Draw the corresponding histogram on graph paper.
Write a paragraph about your data that addresses shape, center, spread, and outliers.
Guided practice: Divide students into groups and assign each group a column from the 2011 NFL Rushing Statistics for Top 50 Rushers:
Rushing Attempts
Total Yards for the Season
Average Yards per Attempt
Average Yards per Game
Number of Rushing Touchdowns
Longest Run of the Season (if you have more than 6 groups, have 2 groups use the same category).
Have each group present their graph and description to the class.
If time is limited, ask students to work on the same column of data.