Individuals, Data Sets, and Statistical Displays

Vocabulary flashcards covering key statistical concepts, types of variables, graphical displays, distribution shapes, and summary measures from the lecture notes.

Individuals

The people or objects described by the data (e.g., a student).

Variables

Characteristics measured on individuals (e.g., the student's test scores, height, weight, etc.).

Data Set

Collection of information from many individuals.

Categorical Variables

Place individuals into groups or categories (e.g., eye color, grade level).

Quantitative Variables

Numerical values where arithmetic makes sense (e.g., height, test scores).

Continuous Variable

A quantitative variable that can take on any value within an interval; fractions/decimals (e.g., height).

Discrete Variable

A quantitative variable with gaps in between the data; whole numbers (e.g., number of students in a class).

Frequency Table

Shows counts for each category.

Relative Frequency Table

Shows proportions or percentages instead of counts.

Bar Chart

A categorical data display where bars represent category counts, with spaces between bars.

Pie Chart

Shows each category as a slice of a whole; best for proportions.

Histogram

Shows quantitative data grouped into bins with no spaces between bars; good for showing shape (skewed, symmetric, bimodal).

Stemplot

Splits numbers into stem (leading digits) and leaf (last digit).

Split Stemplot

A stemplot where each stem appears twice to avoid overcrowding.

Side-by-Side Stemplot

A stemplot that compares two groups directly.

Symmetric Distribution

A distribution shape where left and right sides mirror each other.

Skewed Right

A distribution shape with a long tail on the right.

Skewed Left

A distribution shape with a long tail on the left.

Uniform Distribution

A distribution shape where all values occur with roughly equal frequency.

Bimodal Distribution

A distribution shape with two distinct peaks.

Outliers

Values far from the rest.

Gaps

Empty spaces in the distribution.

Clusters

Groups of values bunched together.

Peaks

High points in the distribution (one peak = unimodal, two = bimodal).

Skewness

Feature of a distribution where tail direction indicates skew.

Spread

How stretched out the data are.

Center

Typical value (mean or median).

Mean

Average; $\text{sum of values} \div \text{number of values}$.

Median

Middle value when data are ordered.

Mode

Most frequent value.

Range

$\text{max} - \text{min}$.

IQR

$\text{Q3} - \text{Q1}$; middle $50\%$ of data.

Standard Deviation

How spread out data are around the mean.

Five-Number Summary

Minimum, Q1 (First Quartile), Median, Q3 (Third Quartile), and Maximum.

Boxplot

Great for comparing distributions across groups; box spans Q1 to Q3, line inside is median, whiskers show typical range, and outliers appear as points beyond the whiskers.