Statistics Chapter 2 Flashcards

Vocabulary flashcards covering key terms from Chapter 2 on organizing and summarizing data.

Qualitative (categorical) variable

A variable whose observations belong to categories or labels rather than numeric values.

Frequency distribution

A table listing each category and the count (frequency) of observations in that category.

Relative frequency distribution

A table listing each category with its relative frequency, i.e., the proportion of observations in that category.

Relative frequency

The proportion of observations in a given category, calculated as its frequency divided by the total number of observations.

Bar graph

A graph with a bar for each category; bar height represents either frequency or relative frequency.

Pareto chart

A bar graph with categories ordered from tallest to shortest by frequency or relative frequency.

Pie chart

A circle divided into sectors where each sector’s area is proportional to the category’s relative frequency.

Dot plot

A plot that places a dot above each value on a number line, showing every individual observation.

Stem-and-leaf plot

A display where each observation is split into a stem (all digits except the final one) and a leaf (the final digit), preserving individual values.

Split stems

A stem-and-leaf variation that splits each stem into two groups (0–4 and 5–9) to reduce clutter.

Histogram

A graph of adjacent bars showing frequencies or relative frequencies for a quantitative variable across equal-width intervals.

Class width

The width of each interval (class) in a histogram; typically computed from (largest − smallest)/number of classes.

Class interval

The endpoints that define each bar (class) in a histogram.

Unimodal

A distribution with a single peak.

Bimodal

A distribution with two distinct peaks.

Uniform

A distribution where frequencies across classes are relatively the same.

Bell-shaped

A distribution that is approximately symmetric and unimodal.

Skewness

Asymmetry in a distribution; left-skewed has a longer left tail, right-skewed has a longer right tail.

Outlier

An observation that lies far from the rest of the data and does not fit the main pattern.

Key (stem-and-leaf)

A short explanation showing how to decode stems and leaves to obtain the actual values.

Quantitative variable

A variable whose observations are numerical values representing magnitudes.

Continuous variable

A quantitative variable that can take any value within an interval (including decimals).

Ordinal variable

A qualitative variable with a natural order among categories.

Nominal variable

A qualitative variable with no natural order among categories.