Summer Vocabulary Flashcards
Categorical Variable
Variable that places an individual into one of several groups or categories.
Census
Study that attempts to collect data from every individual in the population.
Bar Graph
Graph used to display the distribution of a categorical variable or to compare the sizes of different quartiles
Association
Knowing the value of one variable helps predict the value of the other.
Bimodal
A graph of quantitative data with two clear peaks.
Back-to-back Stems
Plot used to compare distribution of a quantitative variable for two groups.
Boxplot
Graph of the five number summary. The box spans the quartiles and shows the spread of the central half of the distribution.
Individuals
Objects described by a set of data. Individuals may be people, animals, or things.
Variable
Any characteristics of an individual. A variable can take different values for different individuals.
Quantitative Variable
Variable that takes numerical values for which it makes sense to find an average.
Discrete Variables
Takes a fixed set of possible values with gaps between. The probability distribution of a discrete random variable gives its possible values and their probabilities.
Continuous
Information that can be measured on a continuum or scale.
Univariate Data
Observations on only a single characteristic or attribute
Bivariate Data
Data on each of two variables, where each value of one of the variables is paired with a value of the other variable
Population
In a statistical study, the entire group of individuals we want information about.
Sample
Subset of individuals in the population from which we actually collect data.
Distribution
Tells what values a variable takes and how often it takes these values.
Inference
Drawing conclusions that go beyond the data at hand.
Frequency Table
Table that displays the count of observations in each category or class.
Relative Frequency Table
Table that shows the percents of observations in each category or class.
Roundoff Error
Difference between the calculated approximation of a number and its exact mathematical value.
Pie Chart
Chart that shows the distribution of a categorical variable as a pie whose slices are sized by the counts or percents for the categories. A pie chart must include all the categories that make up a whole.
Two-Way Table
Table of counts that organizes data about two categorical variables.
Marginal Distribution
The distribution of one of the categorical variables in a 2-way table of counts among all individuals described by the table.
Conditional Distribution
Term that describes the values of one variable among individuals who have a specific value of another variable. There is a separate conditional distribution for each value of the other variable.
Spread
The extent to which a distribution is stretched or squeezed
Segmented Bar Graph
Graph used to compare the distribution of a categorical variable in each of several groups.
Side-by-side Bar Graph
Graph used to compare the distribution of a categorical variable in each of several groups. For each value of the categorical variable, there is a bar corresponding to each group.
Simpson’s Paradox
phenomenon in which a trend appears in several different groups of data but disappears or reverses when these groups are combined.
Dotplot
Simple graph that shows each data value as a dot above its location on a number line.
Shape
Analysis of the geometrical properties of some given set of shapes by statistical methods.
Center
Different measures of the middle of a distribution
Range
Difference between maximum and minimum.
Outlier
Individual value that falls outside the overall pattern of a distribution.
Symmetric
A graph in which the right and left sides are approximately mirror images of each other.
Skewed Right
Right side of graph is much longer than left side.
Skewed Left
Left side of graph is much longer than right side.
Unimodal
A graph of quantitative data with one clear peak.
Multimodal
A graph of quantitative data with more than 2 clear peaks.
Stemplot
Simple graphical display for fairly small data sets that gives a quick picture of the shape of a distribution while including the actual numerical values of the graph.
Splitting Stems
Method for spreading out a stemplot that has too few stems.
Plots
Graphs showing the relation between two variables.
Histogram
Graph that displays the distribution of a quantitative variable. The horizontal axis is marked in the units of measurement for the variable. The vertical axis contains the scale of counts or percents. Each bar in the class represents an equal width class.
Mean
Arithmetic average. Add all values up then divide by number of values.
Median
Midpoint of a distribution. 1/2 of observations are smaller 1/2 are larger.
Interquartile Range
IQR = 3rd quartile - 1st quartile
Five-Number Summary
Smallest observation, 1st quartile, median, third quartile, and largest observation.
Standard Deviation
Statistics that measures the typical distance of the values in a distribution from the mean.
Variance
Average squared deviation of the observations in a data set from their mean.
