unit 1 ap stats vocab

Categorical/Qualitative Variable

Values that are category names or group labels. (examples: color, mood, type of music)

Quantitative Variable

Numerical values of a certain quantity. (examples: height, weight, population of a city)

Frequency Table

Gives the number of cases falling into each category.

Relative Frequency Table

Gives the proportion/percentage of cases falling into each category.

Center

Separates the values roughly in half, it’s in the middle of graphs.

Spread

The range of values from smallest to largest.

Clusters

Natural subgroups that values fall into in a graph.

Gaps

Holes where no values fall in a graph.

Unimodal

A distribution with one peak.

Bimodal

A distribution with two peaks.

Symmetric distribution

Where the two halves of a graph are mirroring each other.

Skewed to the right

The graph gets lower on the right side.

Skewed to the left

The graph gets lower on the left side.

Bell-shaped distribution

The graph dips on two sides and has a large mound in the middle. Looks like an upside-down “U” and shows that the graph has a normal distribution.

Uniform

The values are mostly equal/the graph is in a straight line.

Sample

A part of a population.

Median

The middle number in a set of numbers in numerical order. It’s also equal to the mean of a normal distribution.

Mean

The average of a set of numbers, found by adding all values and dividing by the amount of numbers in the set.

µ

The mean of an entire population.

x̄

The mean of a sample.

Range

The difference between the largest and the smallest value.

Interquartile Range (IQR)

The difference between the largest and smallest values after removing the lower and upper quartiles.

IQR = Q3 – Q1 / 75th percentile minus 25th percentile.

Standard Deviation

The typical distance that each value is from the mean.

Variance

The average of the squared differences from the mean.

Discrete quantitive variable

Takes on a countable number of values. There’s gaps between each of the values. (example: the number of times that a runner finished first in a race)

Continuous Quantitive Variable

Infinite values with no gaps (example: heights between a group of 10 people)