- arithmetic mean
- a measure of center of a data set, calculated by adding up the data values and dividing the sum by the number of data values

- bar graph
- a chart that presents categorical data in a summarized form based on frequency or relative frequency

- bivariate data
- paired data in which each value of one variable is paired with a value of a second variable

- data visualization
- the use of graphical displays, such as bar charts, histograms, and scatter plots, to help interpret patterns and trends in a data set

- empirical rule
- a rule that provides the percentages of data values falling within one, two, and three standard deviations from the mean for a bell-shaped (normal) distribution

- expected value
- a weighted average of the values of a variable where the weights are the associated probabilities

- exponential distribution
- a continuous probability distribution that is useful for calculating probabilities within the time between events

- frequency distribution
- a method of organizing and summarizing a data set that provides the frequency with which each value in the data set occurs

- geometric mean
- a measure of center of a data set, calculated by multiplying the data values and then raising the product to the exponent $\frac{1}{n}$, where
*n*is the number of data values

- histogram
- a graphical display of continuous data showing class intervals on the horizontal axis and frequency or relative frequency on the vertical axis

- interquartile range (IQR)
- a number that indicates the spread of the middle half, or middle 50%, of the data; the difference between the third quartile (
*Q*_{3}) and the first quartile (*Q*_{1})

- median
- the middle value in an ordered data set

- mode
- the most frequently occurring data value in a data set

- normal distribution
- a bell-shaped distribution curve that is used to model many measurements, including IQ scores, salaries, heights, weights, blood pressures, etc.

- outliers
- data values that are significantly different from the other data values in a data set

- percentiles
- numbers that divide an ordered data set into hundredths; often used to indicate position of a data value in a data set

- population data
- data representing all the outcomes or measurements that are of interest

- portfolio
- a collection of financial investments, such as stocks, bonds, mutual funds, certificates of deposit, etc.

- probability distribution
- a mathematical function that assigns probabilities to various outcomes

- quartiles
- numbers that divide an ordered data set into quarters; the second quartile is the same as the median

- sample data
- data representing outcomes or measurements collected from a subset or part of a population

- scatter plot (or scatter diagram)
- a graphical display that shows the relationship between a dependent variable and an independent variable

- standard deviation
- a measure of the spread of a data set that indicates how far a typical data value is from the mean

- time series graph
- a graphical display used to show measurement data plotted versus time, where time is displayed on the horizontal axis

- variance
- the measure of the spread of data values calculated as the square of the standard deviation

- weighted mean
- a measure of center of a data set in which each data value has a corresponding weighting

*x*-axis- the horizontal axis in a rectangular coordinate system

*y*-axis- the vertical axis in a rectangular coordinate system

*z*-score (or*z*-value)- a measure of the position of a data value in the data set, calculated by subtracting the mean from the data value and then dividing the difference by the standard deviation