Chapter 2 Flashcards
Frequency Table
A grouping of qualitative data into mutually exclusive classes showing the number of observations in each class.
The number of observations in each class is called the:
class frequency
Relative class frequencies
converted class frequencies showing the fraction of the total number of observations in each class.
Shows the relationship between a class total and the total number of observations.
example: 50/80 = 0.625
Bar Chart
A graph in which the classes are reported on the horizontal axis and the class frequencies on the vertical axis. The class frequencies are proportional to the heights of the bars.
Pie Chart
A chart that shows the proportion or percent that each class represents of the total number of frequencies.
Relative frequency table
A frequency table with the relative frequency added.
Frequency Distribution
A grouping of data into mutually exclusive classes showing the number of observations in each class.
How can you best decide the number of classes for a frequency distribution table?
n=2^k where k is the number of classes and n is the number of observations. The result of this equation will usually be a good number of classes you should use.
How can you easily determine the class interval (or width)
i ≤ (H - L) / k where i is the class interval, H is the highest observed value, L is the lowest observed value, and k is the number of classes.
Five steps to create a frequency distribution table
1 Decide on the number of classes. n=2^k 2 Determine the class interval or width. i ≤ (H - L) / k 3 Set the individual class limits. 4 Tally the vehicle selling prices into the classes. 5 Count the number of items in each class.
The number of observations in each class
Class Frequency
The halfway point between the lower limits of two consecutive classes
Class midpoint
How do you get the class interval?
Subtract the lower limit of a class from the lower limit of the next class.
How do you determine the beginning of the first class interval?
try to make it a multiple of the class interval.
Histogram
A graph in which the classes are marked on the horizontal axis and the class frequencies on the vertical axis. The class frequencies are represented by the heights of the bars and the bars are drawn adjacent to each other.
Frequency polygon
shows the shape of a distribution and is similar to a histogram. It is a line graph with connected dots.
Cumulative Frequency Polygon
This is how we graphically portray a Cumulative Frequency Distribution
Cumulative Frequency Distribution
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