From book: Elenetery Statics:a Step By Step Approach,by Allan G. Bluman

### Class Width

Class in a frequency distribution is found by subtracting the lower or upper class limit of 1 class from the lower or upper class limit of the next class.

### Categorical Frequency Distribution

Used for data that can be placed in specific categories, (Ex. such as nominal or ordinal-level data.)

### Ungrouped Frequency Distribution

when the range of data values is relatively small, a frequency distribution can be constructed using single data values for each class.

### Grouped frequency Distribution

When the range of data is large, the data must be grouped into classes that are more than one unit in width(.Ex. distribution of the number of hours boat batteries last.)

### Cumlative Frequency

The sum of frequencies accumulated up to the upper boundary of a class in the distribution.

### Frequncy Polygon

is a graph that displays the data by using lines that connect points plotted for the frequencies @ the midpoint of the class. the frequencies are represented by heights of the points.

### Ogive

is a graph that represents the cumulative frequencies for the classes in a frequency distribution.

### pie graph

A circle,divided into according to the percentage of frequencies in each category of the distribution.

### Histogram

is a graph that is displays the data by using contiguous vertical but(Unless the frequency of a class is O) of various heights to represent the frequency of classes.