Stats Unit 2 Vocabulary

Relative Risk

Ratio of proportions between two explanatory variables.

Simpson’s Paradox

Proportions reverse direction under certain conditions.

Outlier

An observation that falls outside the overall pattern of the graph.

Symmetrical Distribution

The right and left side of a histogram are approximately mirror images of each other.

Right Skewed Distribution

The right side of the histogram extends farther out than the left side; characterized by a right tail.

Left Skewed Distribution

The left side of the histogram extends farther out than the right side; characterized by a left tail.

Describing a Distribution

Includes shape, center, spread, and outliers.

Median

The middle value of the distribution.

Resistant

A statistic that does not change when data values change.

Mean (X̄)

The average of a data set.

Range

The difference between the maximum and minimum values in a data set.

Lower Quartile (Q1)

Value below which 25% of the data values fall.

Upper Quartile (Q3)

Value below which 75% of the data values fall.

Interquartile Range

IQR is the difference between the upper quartile and lower quartile (Q3 - Q1).

Five Number Summary

Consists of minimum, Q1, median, Q3, and maximum; used to describe a skewed distribution.

Standard Deviation (S)

Average distance a data value is from the mean.

Mean & Standard Deviation

Used to describe a symmetrical distribution.

Empirical Rule

Describes the percentage of data within one, two, and three standard deviations from the mean: 68%-95%-99.7%.

Standardize z-score

Formula for z-score is (Observation - Mean) / Standard Deviation.