1. Aim: How do we organize and interpret statistical data?
Do Now:
Which task is not a component of an observational study?
(1) The researcher decides who will make up the sample.
(2) The researcher analyzes the data received from the sample.
(3) The researcher gathers data from the sample, using surveys or taking measurements.
(4) The researcher divides the sample into two groups, with one group acting as a control group.

2. Recall:
A teacher marked a set of 32 papers. The grades were as follows: 90, 85, 74, 86, 65, 62, 100, 95, 77, 82, 50, 83, 77, 93, 72, 98, 66, 45, 73, 100, 50, 89, 78, 70, 75, 95, 80, 78, 83, 81, 72, 75.
Find the significant statistical measurements using the 1-var Stats option on the graphing calculator.

3. Recall: Model Problem
A teacher marked a set of 32 papers. The grades were as follows: 90, 85, 74, 86, 65, 62, 100, 95, 77, 82, 50, 83, 77, 93, 72, 98, 66, 45, 73, 100, 50, 89, 78, 70, 75, 95, 80, 78, 83, 81, 72, 75.
STAT  EDIT  1
STAT  CALC  1 ENTER

4. Stem-and-Leaf Plots
Data - Test Scores: 90, 85, 74, 86, 65, 62, 100, 95, 77, 82, 50, 83, 77, 93, 72, 98, 66, 45, 73, 100, 50, 89, 78, 70, 75, 95, 80, 78, 83, 81, 72, 75 5
5 = 55
Key:
Stem
Leaf 3 5 5 8
greatest stem to least 1 2 3 3 5 6 9 2 2 3 4 5 5 7 7 8 8 2 5 6 5
ordered leafs – lowest to highest

5. Stem-and-Leaf Plots
Data - John’s Test Scores: , 82, 86, 82, 85, 84, 85, 93, 73, 82
put in order – lowest to highest
67, 73, 82, 82, 82, 84, 84, 85, 85, 93 5 8 4 3 8 8 6 4 2 2 2 4 5 5 6 3 6 7
Data - Marcia’s Test Scores: , 84, 86, 88, 88, 94, 95, 95, 98, 98 5
5 = 55
Key:

6. 3rd type of graph representing data
Stem-and-Leaf Plots
Data - John’s Test Scores: , 82, 86, 82, 85, 84, 85, 93, 73, 82
67, 73, 82, 82, 82, 84, 84, 85, 85, 93 3 2 7 5 4
3rd type of graph representing data 3 2 7 5 4
A stem-and-Leaf Plot rotated 1/4 turn counterclockwise gives us a general outline format for a histogram

7. A histogram is a bar graph that shows the frequency of occurrence
Histogram/Bar Graph
A histogram is a bar graph that shows the frequency of occurrence
Frequency
Data Results
1. Horizontal axis - data organized in intervals 2. Vertical axis - the frequency of occurrence For each interval, bar drawn to height of frequency No space between bars

8. Histogram of Paper Grades
Model Problem
Recall our previous Paper Grade problem:
Frequency
Grades
Histogram of Paper Grades

9. TI Graphing
2ND  Y= 1
Set WINDOW
GRAPH & TRACE
use right and left
arrows to move thru
intervals.

10. How many students scored better than 80?
Model Problem
Frequency
Grades
How many students scored better than 80?
How many students scored 70 or less?
A cumulative histogram makes it easier to answer such questions

11. How many students scored better than 80? 14
Cumulative Histogram
Cumul at I ve 3 7 18 26 32
Frequency
41-50
41-60
41-70
41-80
41-90
41-100
Grades
How many students scored better than 80? 14
How many students scored 70 or less? 7

12. Approximately what percent of students scored above 70?
Cumulative Histogram 32
100% 0% 26
75% 18
Cumulative Frequency
50%
25% 7 3 3
Grades
Approximately what percent of students scored above 70?
Approximately What percent of students scored 100 or below?

13. Mileage (miles per gallon) for compact cars
Model Problems
Answer the questions below based your interpretations of the histogram.
Frequency
Mileage (miles per gallon) for compact cars
1) In what interval is the greatest frequency found? 2) What is the number of cars reporting mileages between 28 and 31 miles? ) What percent of cars reported mileages from 24 to 27 miles per gallon (to the nearest %)?

14. What is the modal interval? 71-80
Model Problem
240 students took a math test. The frequency table below shows the results. Draw a histogram representing the results.
Frequency
Test Scores
What is the modal interval?
71-80
In what interval will you find the median?
Median is average of the 120th and 121st values. Both are located in the interval.