Chapter 1 Flashcards
The objects described by a set of data. Individuals may be people, animals, or things.
Individuals
Any characteristic of an individual. A variable can take different values for different individuals
Variable
Places an individual into one of several groups or categories
Categorical variable
Takes numerical values for which it makes sense to find an average
Quantitative value
Tells us what the variable takes and how often it takes these variables
Distribution
One of the categorical variables in a two-way table of counts is the distribution of that variable among all individuals described by the table
Marginal distribution
Describes the values of that variable among individuals who have a specific value of another variable. There is a separate conditional distribution for each value of the other variable.
Conditional distribution
There is this between 2 variable if knowing the value of one variable helps to predict the value of the other. If knowing the value of 1 variable does not help predict the value of the other, then there is no association between the variables
Association
Each data value is gown as a dot above its location on a number line
Dot plot
A distribution is this if the right or left sides of the graph are approximately mirror images of each other
Symmetric
Right side of graph is much longer than left
Skewed to the right
Left side of graph is much longer than the right side
Skewed to the left
Have a single peak
Unimodal
Give a quick picture of shape of distribution while including the actual numerical values in the graph
Stemplot
X(with a line over it)= the sum of X i over n
Mean of x
Is the midpoint of a distribution, the number such that about half the observations are smaller and about half are larger.
Median
Lies 1 quarter up the list
1st quartile
Lies at the median
2nd quartile
Lies 3 quarters up the list
3rd quartile
Measure the range of the middle 50% of the range
Interquartilerange (IRQ)
Call an observation an outlier if it falls more than 1.5 X IQR above the 3rd quartile or below the 1st quartile
The 1.5 X IQR rule for outliers
Consists of the smallest observation, the 1st quartile, the median, the 3rd quartile, and the largest observation, written in order from smallest to largest
Five-number summary
Measures the typical distance of the values in a distribution from the mean
Standard devaition
The average squared deviation
Variance
