Individual
An object described by a set of data.
Variable
Any characteristic of an individual, which can take different values for different individuals.
Categorical Variable
A characteristic of an individual that places the individual into one of several groups.
Quantitative Variable
A characteristic of an individual that takes numerical values for which arithmetic operations such as adding and averaging make sense.
Distribution
The pattern of variation of a variable that describes what values the variable takes and how often it takes these values.
Range
The difference between the largest and smallest observations, which serves as a nonresistant measure of spread.
Spread
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Frequency
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Outlier
An individual observation that falls outside of the overall pattern of the graph, which can be calculated by multiplying the interquartile range by 1.5 and adding it to the third quartile or subtracting it from the first quartile.
Center
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Shape
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Skew
A distribution in which either the right or left side of the display contains the larger values and is more prominent than the left side.
Symmetry
A distribution in which the right and left sides of the display are approximately mirror images of each other.
Dot Plot
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Histogram
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Stemplot
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Split Stemplot
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Back-to-Back Stemplot
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Time Plot
A graphical display of data that is useful for showing the pattern of changes over time if there are not many variables, in which each observation of a variable is plotted against the time at which it was meastured, the time is shown on the horizontal axi
Mean
The arithmetic average of a distribution, denoted x (x-bar), which is found by adding all of the values of the observations and dividing the total sum by the total number of observations and serves as a nonresistant measure of spread.
Summation
The sum of all of the numbers in a set, denoted sigma.
Median
The midpoint of a distribution, denoted M, which is found by arranging all of the observations in order of size from smallest to largest and determining what number falls in the center of the arrangement and serves as a resistant measure of spread.
Resistant
A measure of data distribution that is not impacted by the influence of extreme observations. Such measures include the median, and exclude the mean, range.
Quartile
The denotation of the middle half that is resistant and can be found by calculating the median of the regions either left (first, denoted Q subscript 1) or right (third, denoted Q subscript 3) of the median.
Interquartile Range
The distance between the first and the third quartiles, denoted IQR, and found by subtracting the first quartile from the third.
Five-Number Summary
A description of data set that consists of the smallest observation, the first quartile, the median, the third quartile, and the largest observation, written in order from smallest to largest.
Minimum
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Maximum
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Boxplot
A graphical distribution of the five-number summary, which uses a central box to span the quartiles, a line in the box to mark the median, and lines extending from the box to connect the smallest and largest observations. It is useful for side-by-side com
Modified Boxplot
A graphical distribution of the five-number summary, which uses a central box to span the quartiles, a line in the box to mark the median, lines extending from the box to connect the smallest and largest observations, and individual "x" marks to plot the
Standard Deviation
The square root of the variance, denoted s, which is calculated by adding all of the deviations squared and multiplying it by one over one less than the number of total observations. It is a nonresistant measure of the spread about the mean and should be
Variance
The average of the deviations squared, denoted s squared.
Bar Graph
A bar-based, graphical display of data that shows categorical variables, whose measurements do not necessarily add to one hundred percent.
Pie Chart
A circular, graphical display of data that show categorical variables, whose measurements must add to one hundred percent.
Exploratory Data Analysis
The use of graphs or other numerical summaries to describe the variables in a data set and the relations among them.
What is the significance of the x-scl?
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How do you choose the values of x-minimum and x-maximum?
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What is the significance of y-maximum?
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How is the stemplot of a distribution related to its histogram?
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What is the relationship between variance and standard deviation?
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Is standard deviation resistant or nonresistant to extreme observations?
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Count
The number or percentage of individuals that fall within each category of a particular data display.
Linear Transformation
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