Statitistics Revivew Ch.1-3

• A grouping of qualitative data into mutually exclusive classes showing the number
• of observations in each class.

• 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.

A chart that shows the proportion or percent that each class represents of the total number of frequencies.

A grouping of data into mutually exclusive classes showing the number of observations in each class.

-Class frequencies can be converted to relative class frequencies to show the fraction of the total numberof observations in each class. 

-A relative frequency captures the relationship between a class total and the total number of observations.

Class interval:  The class interval is obtained by subtracting the lower limit of a class from the lower limit of the next class

.

  A useful recipe to determine the number of classes (k)is the “2 to the k rule.”  such that 2^k > n.

i.e.  There were 180 vehicles sold, so n = 180. If we try k =7, then 2⁷  = 128, somewhat less than 180. Hence, 7 is not enough classes. If we let k = 8, then 28  = 256, which is greater than 180. So the recommended number of classes is 8.

• The formula is: i ≧ (H-L)/k where "i" is the class interval, H is the highest observed value, L is the lowest observed value, and k isthe number of classes.
• 
• Round up to some convenient number, such as a multiple of 10 or 100. Use a class width of $400

• To convert a frequency distribution to a relative frequency distribution, each of the class frequencies is divided by the total number of observations.
•