Graphic display of data Section 2-2 Graphic display of data

Homework Examples: Page 52; #29

Homework Examples: Page 52; #31

II. Section 2-2 A. Stem and Leaf Plot 1. Use the extreme values as your starting point. 2. Go through the data points, placing the leaves beside the appropriate stems. 3. If you have too many data points, you can use two lines per stem, with 0-4 consisting of the first line, and 5-9 on the second line.

EXAMPLE: Use the table of 30 numbers below to fill in a stem and leaf plot 72 84 61 76 104 86 92 80 88 98 97 82 67 70 81 89 74 73 85 78 91 83 Stem Leaves 6 7 8 9 10 1 2 6 4 4 Continue in this manner until all 30 data points are represented in the stem and leaf plot.

EXAMPLE: Use the table of 30 numbers below to fill in a 2 line stem and leaf plot For a two-line plot, use the first line for 0-4, and the second line for 5-9. 72 84 61 76 104 86 92 80 88 98 97 82 67 70 81 89 74 73 85 78 91 83 Stem Leaves 6 7 8 9 10 1 2 6 6 Continue in this manner until all 30 data points are represented in the stem and leaf plot. 4 6 4

1. Use a horizontal line, numbered from lowest data value to highest. B. Dot Plot 1. Use a horizontal line, numbered from lowest data value to highest. a. Place a dot on the line at each data point. 1) This allows you to see visually whether you have a tight grouping of data points, and where it is, if it exists. 55 respondents: 6 have $5 on their person. 5 have $10 on their person. 3 have $15 on their person. 7 have $20 on their person. 9 have $25 on their person. 7 have $30 on their person. 4 have $35 on their person. 9 have $40 on their person. 3 have $45 on their person. 2 have $50 on their person. 15 respondents: 2 have no siblings 3 have 1 sibling 5 have 2 siblings 3 have 3 siblings 2 have 4 siblings

1. Used to describe parts of a whole. C. Pie Chart 1. Used to describe parts of a whole. a. Multiply the relative frequency you calculated earlier by 360 (the number of degrees in a circle) to find the number of degrees that each class will consist of. 1) The calculated number of degrees corresponds to the interior angle in the circle. a) Use a protractor to draw your angles. Gymnastics: .11 * 360 = 39.60 Swimming: .27 * 360 = 97.20 Soccer: .30 * 360 = 1080 Track: .20 * 360 = 720 Tennis: .12 * 360 = 43.20 Make sure that your total angles add up to 3600!!

D. Scatter Plot 1. Used to visually examine the possible relationship between two different elements. a. Place one element on the vertical axis, and the other on the horizontal. 1) Graph them as if one was the x value of an ordered pair and the other was the y-value. 2. The closer the dots are to being linear, the stronger the relationship. a. If the slope is upward, the relationship has a positive correlation. b. If the slope is downward, the relationship has a negative correlation.

D. Scatter Plot 3. To do a Scatter Plot on the TI-84, follow these steps. A. Turn STAT Plots on 1) 2nd y=, Enter 2) Highlight Plot On, Enter B) Go to STAT and Edit 1) Enter x-values into L1, and y-values into L2. C) Press the Window button, and set your x-min and x-max values to match the data in L1. 1) Repeat for y-min and y-max values to match L2. D) Press graph to see the scatterplot. 4. To get the equation of the line of best fit, go to STAT and Calc, then select LinReg (4). A) The slope and y-intercept will be given to you. 5. To graph the line with the scatterplot, manually enter the equation into the y= window and press Graph.

Assignments: Classwork:   Pages 62-63;  #1-16 All Homework:  Pages 63-65,  #18-32 Evens   Study for Quiz on 2-1 & 2-2