AP Statistics Unit 1.1 Flashcards – Exploring One-Variable Data

Categorical Variable

A variable that takes on values that are category names or group labels.

Quantitative Variable

A variable that takes on numerical values for a measured or counted quantity.

Discrete Quantitative Variable

A quantitative variable that takes on a finite or countable number of values, with "gaps" between values.

Continuous Quantitative Variable

A quantitative variable that can take on uncountable or infinite values with no gaps, such as height or weight.

Frequency

The number of cases falling into each category.

Relative Frequency

The proportion or percentage of cases falling into each category.

Bar Graph

A graphical display for categorical data using bars to show frequency or relative frequency.

Dotplot

A display of data using dots, where each dot represents an observation.

Histogram

A graphical display for quantitative data, showing the distribution of values.

Stemplot (Stem-and-Leaf Plot)

A display that separates data values into a "stem" (first digits) and a "leaf" (last digit).

Cumulative Relative Frequency Plot

A graph showing the accumulation of relative frequencies over the range of values.

Distribution of a Variable

Describes the possible values a variable can assume and how often each occurs.

Shape of a Distribution

The pattern of the distribution, such as symmetric, skewed right, skewed left, bell-shaped, or uniform.

Symmetric Distribution

A distribution where the two halves are mirror images of each other.

Skewed Right Distribution

A distribution that spreads far and thinly toward higher values.

Skewed Left Distribution

A distribution that spreads far and thinly toward lower values.

Bell-Shaped Distribution

A symmetric distribution with a center mound and sloping tails.

Uniform Distribution

A distribution where all values are equally likely.

Center

A measure that separates the values into two equal halves (median) or is calculated as an average (mean).

Spread

The range of values from smallest to largest, including measures like range, IQR, variance, and standard deviation.

Outlier

A data value that falls far outside the overall pattern of the distribution.

Mode

The most frequently occurring value(s) in a dataset.

Cluster

A grouping of data points that naturally fall into subgroups.

Gap

A section of the distribution where no data values fall.

Empirical Rule

A rule stating that for a normal distribution, approximately 68% of values fall within one standard deviation, 95% within two, and 99.7% within three.