1. Unit 5
Stats

2. Section 1 – Key Statistical Concepts (representing data)

3. A collection of individuals (data) about which we want to draw conclusions
The students at West Ottawa
The collection of information from the WHOLE POPULATION
Polling ALL students at West Ottawa
Random
Biased
Selecting in the
IB program
A subset of the population.
Selecting students as
they walk in the door
Polling the students we have selected
from walking in the door
A subset of the population.

4. Information about the population that can be represented by numbers
More on these to come!
Information about the population that can be represented by categories
The quantities we are polling about
More on these to come!
How the population is “spread”
Data values that are much larger (or smaller) than the general body of data

5. Example 1:
The Student Senate is counting the number of students wearing black and white for Spirit Week. There are 2200 total students enrolled at West Ottawa High School. The Student Senate President counts the number of students wearing black and white in a randomly selected classroom containing
30 students.
Population?________________ Sample? _____________ Variable? ___________________
Wearing black
and white
Selected class
Students of WO

6. Example 2
Determine whether each situation would produce a random sample. Write yes or no and explain your answer.
surveying of students at the Galaxy Dance of whether or not they like to dance
b. polling every 5th person who walks into the mall about what is their favorite color no
yes

7. Frequency Histograms
Column Graph vs Histogram

8. Studying the number of students who attended Homeless for a night
Example 3:
Determine whether each situation would produce a discrete or continuous set:  
Studying the number of students who attended Homeless for a night
b. Studying the length of a strand of mutated bacterial
discrete
continuous

9. Center: discussions of the middle of data
Spread: How spread out (distributed) is data
most frequently occurring value
Advantage: can be used for non-numeric data
Disadvantage: can take more than one value
Average!
Advantage: Takes into account all of the data
Disadvantage: Can be skewed by outliers
Middle number
Advantage: Is not skewed by outliers
Disadvantage: Does not take into account all the data

10. Example 4

12. Example 5

13. Example 6 Mean: 3.25 Median: 3 (28th data value : half of the 55)
Mode: 3

14. Example 7

15. 4.2: Representing Data

17. 5 number summary 5-number summary
Min: _____ Q1: ______ Median: _______ Q3: _______ Max: ________
IQR (interquartile range): _______________
Middle
Median of first grouping
Median of second grouping
Q3 – Q1

18. Min: _____ Q1: ______ Median: _______ Q3: _______ Max: ________   
Min: _____ Q1: ______ Median: _______ Q3: _______ Max: ________
IQR (interquartile range): _______________

19. answer
Box and Whiskers

21. 14.D/E Cumulative Frequency Tables

22. add to notes
Mean:

23. Mean from a Freq Table
Median: = 50 freq therefore the median is the av of 25th and 26th items
Med: 0
Med: 0
Mean: .4
(0 passengers)

24. add to notes Cumulative Frequency graphs measure data
up to a certain value.

25. Percentiles What percent of the data is BELOW you!
90% means 90% of population is below you.
Is it possible to be in the 100th percentile?

29. Merits:
The Median is the only measure that will locate the true center
The Mean is only an accurate measure if the data is distributed evenly