1. Random sample of patrol officers, each scored 1-5 on a cynicism scale
Sample 1 (n=10)
Officer Score Mean Diff. Sq.
Sum
Variance (sum of squares / n-1) s
Standard deviation (sq. root of variance) s

2. Depicting the distribution of continuous variables: the histogram
Distributions depict the frequency (number of cases) at each value of a variable. Here there is one variable: age, measured on a scale of A case is a single unit that “contains” all the variables of interest. Here each student is a case Frequency means the number of cases – students – at a single value of a variable. Frequencies are always on the Y axis Values of the variable are always on the X axis
Trend line
Y - axis
How many at each value/score
Value or score of variable
X - axis
What is the area under the trend line “made up of”? Cases, meaning students (arranged by age)

4. Depicting distribution of a categorical variable: the bar graph
Distributions depict the frequency (number of cases) at each value of a variable. Here there is one variable with two values: gender (M/F). A case is a single unit that “contains” all the variables of interest. Here each student is a case Frequency means the number of cases – students – at a single value of a variable. Frequencies are always on the Y axis Values of the variable are always on the X axis
N = 32
n=17
n=15
Y - axis
How many at each value/score
Value or score of variable
X - axis
Bars are “made up of” cases. Here that means students, arranged by the variable gender
Distributions illustrate how cases cluster or spread out
according to the value or score of the variable. Here
the proportions of men and women seem about equal.