The Basics (Variables & Data)
What are Individuals?
Objects described by a set of data, such as people, animals, or things.
What is Shape?
The pattern of variation of a variable, often described as symmetric, skewed left, or skewed right.
What is a Frequency Table?
A table that shows the counts of individuals in each category of a categorical variable.
What is a Dotplot?
A simple display where each data value is shown as a point placed above its location on a continuous number line.
What is a Two-Way Table?
A grid that describes two categorical variables, organizing counts according to a row variable and a column variable.
What is a Variable?
Any attribute or characteristic of an individual that can take different values for different individuals.
What is Center?
A representative value that indicates the midpoint of a distribution, such as the mean or median.
What is a Relative Frequency Table?
A table that shows the proportions or percentages of individuals in each category instead of raw counts.
What is a Stemplot (Stem-and-Leaf Plot)?
A display for small quantitative data sets that separates each observation into a stem and a leaf.
What is a Marginal Distribution?
The distribution of values of one categorical variable among all individuals in a two-way table, found in the row/column totals.
What is a Categorical (Qualitative) variable?
A variable that places an individual into one of several groups or categories.
What is Variability (Spread)?
A numerical value that describes how spread out the data points are from one another or from the mean.
What is a Pie Chart?
A circular display showing how a whole is divided into categories, where each slice's area corresponds to its relative frequency (must sum to 100%).
What is a Split Stemplot?
A modification of a stemplot used when data values are clustered closely together, splitting stems into equal intervals (like 0–4 and 5–9).
What is a Conditional Distribution?
The distribution of values of one categorical variable among individuals that have a specific value of another variable.
What is a Quantitative variable?
A variable that takes numerical values for which it makes sense to find an average.
What is Skewed?
A distribution where one tail extends much farther out than the other side.
What is a Segmented Bar Graph?
A stacked bar graph used to compare the conditional distributions of a categorical variable across groups.
What is a Histogram?
A visual display for quantitative data that uses touching bars to show the frequency of data falling into equal-width bins/intervals.
What is the 5-Number Summary?
A set of five numbers consisting of the Minimum, First Quartile Q1, Median, Third Quartile Q3, and Maximum.
What is Statistics (or Data Analysis)?
The science and art of collecting, analyzing, displaying, and drawing conclusions from data.
What is an Outlier?
An individual value that falls clearly outside the overall pattern of the rest of the distribution.
What is a Bar Graph?
A chart where each category is represented by a bar whose height shows the category's frequency or relative frequency, with spaces between bars.
What is a Boxplot?
A graph based on the Minimum, Q1, Median, Q3, and Maximum that highlights outliers and shows center and spread.
What is Standard Deviation?
A statistic ($s_x$) that measures the typical distance of data values from the mean in a distribution.