Statistics 312 5 Displays of Numerical Data We want ways to present the information in a data set Ex Data were collected on the ages at which students finished a Master s degree 1 Statistics 312 5 Displays of Numerical Data 2 Statistics 312 5 Displays of Numerical Data 3 Statistics 312 5 Displays of Numerical Data Read pp 56 57 Prob 2 14a 2 18a 4 Statistics 312 5 Displays of Numerical Data 5 A frequency distribution or frequency table for a data set population or sample consists of groups of possible values called classes or class groupings for a numerical variable and the number of measurements or observations in each class called frequencies Often each frequency is converted to a proportion or percentage of the total number of observations called a class relative frequency Ex The data below represents stress test scores on a scale of 0 low to 150 high of 140 employees of a large engineering firm Statistics 312 5 Displays of Numerical Data 6 A frequency distribution would consist of one of the three left most columns giving the classes themselves and one or more of the right most columns giving various versions of the class frequencies Class Class 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 110 10 19 20 29 30 39 40 49 50 59 60 69 70 79 80 89 90 99 100 109 Midpoint 15 25 35 45 55 65 75 85 95 105 Freq 1 8 14 19 27 21 22 15 11 2 Rel Freq 007 057 100 136 193 150 157 107 079 014 Cum Freq 1 9 23 42 69 90 112 127 138 140 Note MINITAB does not have a frequency distribution command but frequencies are available as optional output from a histogram command Statistics 312 5 Displays of Numerical Data Double click below horizontal axis 7 Statistics 312 5 Displays of Numerical Data 8 Statistics 312 5 Displays of Numerical Data 9 Statistics 312 5 Displays of Numerical Data 10 Statistics 312 5 Displays of Numerical Data 11 Statistics 312 5 Displays of Numerical Data Read pp 57 64 Prob 2 14bcdeh 2 18be 12