1. Understand the importance of data context
AP Statistics Objectives Ch2
Understand the importance of data context
Distinguish between Categorical and Quantitative Variables
Understand rows and columns of a data table

2. observational unit (case) variable data table Variability
Vocabulary
data (datum)
statistic
context
observational unit (case)
variable
data table
Variability
quantitative
categorical

3. Keep In Mind
Calculator Skills
Vocabulary
Chp 2 Assignment

4. Keep In Mind
1. This distinction between categorical and quantitative variables is quite important because determining which statistical tools to use for analyzing a given set of data often depends on the type of variables involved.

5. Keep In Mind -How many hours you have slept in the past 24 hours
-Whether you have slept at least 7 hours in the past 24 hours
2. Notice how the variable of sleep time can be measured either quantitatively or categorically. This is true of many variables: The classification of the variable often depends on how the quantity is measured.

6. Keep In Mind
3. A variable that takes on numerical values that are really just category labels, such as a zip code, is categorical.

7. Calculator Skills
To enter data:
Hit the STAT button, and choose EDIT from the menu. You’ll see a set of columns labeled L1, L2, and so on. Here is where you can enter, change, or delete a set of data.
Let’s enter the heights (in inches) of the five starting players on a basketball team: 71, 75, 75, 76, and 80.

8. Calculator Skills
To change a datum:
Suppose the 76” player grew since last season; his height should be listed as 78”. Use the arrow keys to move the cursor onto the 76, then change the value and ENTER the correction.

9. Calculator Skills
To add more data:
We want to include the sixth man, 73” tall. It would be easy to simply add this new datum to the end of the list. However, sometimes the order of the data matters, so let’s place this datum in numerical order. Move the cursor to the desired position (atop the first 75). Hit 2nd INS, then ENTER the 73 in the new space.

10. Calculator Skills
To delete a datum:
The 78” player just quit the team. Move the cursor there. Hit DEL. Bye.

11. Calculator Skills
To clear the data list:
Finished playing basketball? Move the cursor atop L1. Hit CLEAR, then ENTER (or down arrow). You should now have a blank data list, ready for you to enter your next set of values.

12. Calculator Skills
Lost a data list:
Oops! Is L1 now missing entirely? Did you delete L1 by mistake, instead of just clearing it? Easy problem to fix: buy a new calculator. No? OK, then simply go to the STAT EDIT menu, and run SetUpEditor to recreate all the lists.

13. Assignment
Chapter 2 pp #2, 8, 20, 24

14. Chapter 1 & 2 Vocabulary 1. Variable -
any characteristic of a person or thing that can be assigned a number or a category
2. Observational unit (aka ‘case’)-
the person or thing to which the number or category is assigned

15. Chapter 1 & 2 Vocabulary 3. Data – (singular is datum) 4. Statistic -
consist of the numbers or categories recorded for the observational units in a study
4. Statistic -
Particular calculations made from data

16. Chapter 1 & 2 Vocabulary 4. Variability-
the phenomenon of a variable taking on different values or categories from observational unit to observational unit

17. Chapter 1 & 2 Vocabulary 5. Context-
ideally tells Who was measured, What was measured, How the data were collected, Where the data were collected, and When and Why the study was preformed.
(referred to as the W’s)
Note: “Who” doesn’t have to be a person
“What” is the variable (careful)

18. Chapter 1 & 2 Vocabulary 6. Data table-
an arrangement of data in which each row represents a case and each column represents a variable

19. Chapter 1 & 2 Vocabulary 7. Quantitative variable -
measures a numerical characteristic such as height
8. Categorical variable -
records a group designation such as gender
9. Binary variable -
categorical variables with only two possible categories, for example,
male and female