Descriptive Statistics Flashcards
Bins (numerical data); classes (categorical data)
The nonoverlapping groupings of data used to create a frequency distribution
Box plot
A graphical summary of data based on the quartiles of a distribution.
Categorical data
Data for which categories of like items are identified by labels or names. Arithmetic operations cannot be performed on this kind of data
Coefficient of variation
A measure of relative variability computed by dividing the standard deviation by the mean and multiplying by 100.
Correlation coefficient
A standardized measure of linear association between two variables that takes on values between —1 and + 1. Values near —1 indicate a strong negative linear relationship, values near +1 indicate a strong positive linear relationship, and values near zero indicate the lack of a linear relationship.
Covariance
A measure of linear association between two variables. Positive values indicate a positive relationship; negative values indicate a negative relationship.
Cross-sectional data
Data collected at the same or approximately the same point in time.
cumulative frequency distribution
A tabular summary of quantitative data showing the number of data values that are less than or equal to the upper class limit of each bin.
Data
The facts and figures collected, analyzed, and summarized for presentation and interpretation.
Empirical Rule (68-95-99.7)
A rule that can be used to compute the percentage of data values that must be within 1, 2, or 3 standard deviations of the mean for data that exhibit a bell-shaped distribution.
Frequency distribution
A tabular summary of data showing the number of data values in each of several nonoverlapping bins.
Geometric mean
A measure of central tendency that is calculated by finding the nth root of the product of n values.
Growth factor
The percentage increase of a value over a period of time is calculated using the formula (1 - bake). A value less than 1 indicates negative growth, whereas a value greater than 1 indicates positive growth. The value cannot be less than zero.
Histogram
A graphical presentation of a frequency distribution, relative frequency distribution, or percent frequency distribution of quantitative data constructed by placing the bin intervals on the horizontal axis and the frequencies, relative frequencies, or percent frequencies on the vertical axis.
Interquartile Range (IQR)
The difference between the third and first quartiles.
mean (arithmetic mean)
A measure of central tendency computed by summing the data values and dividing by the number of observations.
Median
A measure of central tendency provided by the value in the middle when the data are arranged in ascending order.
Mode
A measure of central tendency, defined as the value that occurs with greatest frequency.
Observation
A set of values corresponding to a set of variables.
Outlier
An unusually large or unusually small data value.
percent frequency distribution
A tabular summary of data showing the percentage of data values in each of several nonoverlapping bins.
Percentile
A value such that approximately p percent of the observations have values less than the pth percentile; hence, approximately (100 - p) percent of the observations have values greater than the pth percentile. The 50th percentile is the median.
Population
The set of all elements of interest in a particular study.
Quantitative data
Data for which numerical values are used to indicate magnitude, such as how many or how much. Arithmetic operations such as addition, subtraction, and multiplication can be performed on this data.
Quartile
The 25th, 50th, and 75th percentiles, referred to as the first quartile, second quartile (median), and third quartile, respectively. These can be used to divide a data set into four parts, with each part containing approximately 25% of the data.
Random sampling
Collecting a sample that ensures that: (1) each element selected comes from the same population and (2) each element is selected independently.
Random variable
A quantity whose values are not known with certainty.
Range
A measure of variability, defined to be the largest value minus the smallest value.
Relative frequency distribution
A tabular summary of data showing the fraction or proportion of data values in each of several nonoverlapping bins.
Sample
A subset of the population.
Scatter chart
A graphical presentation of the relationship between two quantitative variables. One variable is shown on the horizontal axis and the other on the vertical axis.
Skewness
A measure of the lack of symmetry in a distribution.
Standard deviation
A measure of variability computed by taking the positive square root of the variance.
Time series data
Data that are collected over a period of time
Variable
A characteristic or quantity of interest that can take on different values.
Variation
Differences in values of a variable over observations.
z-score
A value computed by dividing the deviation about the mean (x1 - x) by the standard deviation σ. It is referred to as a standardized value and denotes the number of standard deviations that x is from the mean.
