Statistics Chapter 2
Variable
A characteristic that varies from one person or thing to another.
Pie chart
A disk divided into wedge-shaped pieces proportional to the relative frequencies of the qualitative data.
Discrete variable
A variable whose possible values can be listed, even though the list may continue indefinitely. A discrete variable usually involves a count of something. EX: number of cars, siblings etc...
Continuous variable
A variable whose possible values form some interval of numbers. Usually involves a measurement of something, such as the height of a person, weight of a newborn, etc...
Continuous data
Values of a continuous variable.
Constructing a relative frequency distribution of qualitative data
1) Obtain a frequency distribution of the data 2) Divide each frequency by the total number of observations.
Frequency distribution
A listing of the distinct values and their frequencies.
Relative frequency distribution of qualitative data
A listing of the distinct values and their relative frequencies.
Observation
An individual piece of data.
Histogram
Displays the classes of the quantative data on a horizontal axis and the frequencies (relative frequencies, percents) of those classes on a vertical axis. The frequency (relative frequency, percent) of each class is represented by a vertical bar whose height is equal to the frequency (relative frequency, percent) of that class. The bars should touch each other.
Distribution of a data set
Is a table, graph or formula that provides the values and how often they occur.
Descriptive statistics
Methods for organizing and summarizing information.
Class mark
The average of the two class limits of a class.
Class midpoint
The average of the two cut points of a class.
Data set
The collection of all observations for a particular variable is called a data set.
Class width
The difference between the cut points of a class
Class width
The difference between the lower limit of a class and the lower limit of the next higher class.
Upper class limit
The largest value that could go into a class.
Frequency
The number of times a particular distinct value occurs.
Relative frequency
The ratio of the frequency to the total number of observations. It is just a percentage expressed as a decimal.
Lower class cutpoint
The smallest value that could go in a class.
Upper class cutpoint
The smallest value that could go in the next higher class (equivalent to the lower cut point of the next higher class.)
Lower class limit
The smallest value that could go into a class.
Sample data
The values of a variable for a sample of the population.
Population data
The values of a variable for the entire population
Discrete data
Values of a discrete variable.
Qualitative data
Values of a qualitative variable
Quantitative data
Values of a quantitative variable
Data
Values of a variable
Qualitative variables
Variables that yield nonnumerical information.
Quantitative variables
Variables that yield numerical information.