Variables
Variable
A characteristic of an individual. or A variable tastes different values for different individuals.
Median
The midpoint of a distribution (data line)
Distribution
Tells us what values the variable takes and how often it takes these values
Dot plot
Each data value is shown as a dot above its location on a number line
Variance
The average squared distance (s 2/x)
Individuals
Person, animal, or thing
Skewed data
When one side of the graph is longer than the other side
5 number summary
a distribution consisting of the smallest observation,Q1, median, Q3, and the largest observation.
Stemplot
Gives us a quick picture of the shape of a distribution while including the actual numerical values.
1.5 and IQR rules for outliers
observations are called outliers if it falls more than 1.5 above the third quartile or below the first quartile
Catagorical
Places an individual into one group or several
Symmetric
When the left and right sides of the graph are approximately mirror images of eachother
Conditional Distribution
A variable describes the values of that variable among individuals who have a specific value of another variable. (There is a separate conditional value for each value.)
Histogram
A graph (not a bar graph) used to represent the frequency distribution of a few data points of one variable
Association
Quantitative
Takes numerical values for which it makes sneeze to find an average
Mean
To find the mean of a set of observations, add their values and divide by the number of observations
Marginal Distribution
One of the catagorical variables in a two-way table of counts is the distribution of vales of that variable among all individuals described by the table.
Boxplot
A method for graphically demonstrating the locality, spread, and skewness of numerical data
Simpsons paradox
An association between two variables that holds for each individual value of a third variable can be changed or even reversed when the data for all values of the third variable are combined
Standard Deviation
Measures the average distance of the observations from their mean. (It is calculated by finding an average of the squared distance and then taking the square root.)