frequency distribution
organization of raw data in table form, using classes and frequencies.categorical frequency distribution
Classes must be mutually exclusive
Class must be continuous (every class must be included even if they have no value)
classes must be equal in width
categorical frequency distribution
data that can be placed in specific categories, such as nominal or ordinal-level data.
grouped frequency distribution
when data is grouped into classes that are more than one unit in width.
lower class limit
represents smallest data value that can be included in the class
upper class limit
represents largest data value that can be included in the class.
class boundaries
Used to separate classes so there are no gaps in frequency distribution.
Class boundaries should have one additional place value than class limit and end in a 5.
class width
subtract lower or upper class limit of one class from the lower or upper class limit of the next class.
class midpoint (Xsubscript m)
(lower boundary + upper boundary)/2
or
(lower limit + upper limit)/2
Numerical location of the center of the class.
open ended distribution
have no specific beginning or ending value.
For grouped frequency distribution, it does not need to have an equal width to other classes.
cumulative frequency distribution
shows the number of data values less than or equal to a specific value, usually the upper boundary
ungrouped frequency distribution
frequency distribution can be constructed using single data values for each class. Happens when range of data values is small.
histogram
graph that displays the data by using contiguous vertical bars (unless the frequency of a class is 0) of various heights to represent the frequencies of the classes.
Frequency on y axis and class boundaries on x axis.
bar graph
frequency polygon
graph that displays the data by using lines that connect points plotted for the frequencies at the midpoints of the classes. The frequencies are represented by the heights of the points.
ogive/ cumulative frequency graph
Graph representing the cumulative frequencies for the classes in frequency distribution.
relative frequency graph
uses proportions instead of raw data as frequencies
Used when proportion of data values that fall into a gien class are more important than the actual number of data values that fall into a class.
To convert a frequency into a proportion or relative frequ
pareto chart
represent a frequency distribution for a categorical variable, and the frequencies are displayed by the heights of vertical bars, which are arranged in order from highest to lowest.
time series graph
represents data that occur over a specific period of time.
compound time series graph
if two or more lines are used on the same graph
stem and leaf plot
data plot that uses part of the data value as the stem and part of the data value as the leaf to form groups or classes.