AP Statistics Unit 1 Vocabulary

The science and art of collecting, analyzing, and drawing conclusions from data.

An object described in a set of data. Individuals can be people, animals, or things.

An attribute that can take different values for different individuals.

Assigns labels that place each individual into a particular group, called a category.

Takes number values that are quantities—counts or measurements.

A quantitative variable that takes a fixed set of possible values with gaps between them.

A quantitative variable that can take any value in an interval on the number line.

Of a variable, tells us what values the variable takes and how often it takes those values.

Shows the number of individuals having each value.

Shows the proportion or percent of individuals having each value.

Shows each category as a bar. The heights of the bars show the category frequencies or relative frequencies.

Shows each category as a slice of the "pie." The areas of the slices are proportional to the category frequencies or relative frequencies.

A table of counts that summarizes data on the relationship between two categorical variables for some group of individuals.

Gives the percent or proportion of individuals that have a specific value for one categorical variable.

Gives the percent or proportion of individuals that have a specific value for one categorical variable and a specific value for another categorical variable.

Gives the percent or proportion of individuals that have a specific value for one categorical variable among individuals who share the same value of another categorical variable (the condition).

Displays the distribution of a categorical variable for each value of another categorical variable. The bars are grouped together based on the values of one of the categorical variables and placed side by side.

Displays the distribution of a categorical variable as segments of a rectangle, with the area of each segment proportional to the percent of individuals in the corresponding category.

A modified segmented bar graph in which the width of each rectangle is proportional to the number of individuals in the corresponding category.

There is an association between two variables if knowing the value of one variable helps us predict the value of the other. If knowing the value of one variable does not help us predict the value of the other, then there is no association between the variables.

Shows each data value as a dot above its location on a number line.

A distribution is roughly symmetric if the right side of the graph (containing the half of observations with the largest values) is approximately a mirror image of the left side.

A distribution is skewed to the right if the right side of the graph is much longer than the left side. A distribution is skewed to the left if the left side of the graph is much longer than the right side.

Shows each data value separated into two parts: a stem, which consists of all but the final digit, and a leaf, the final digit. The stems are ordered from lowest to highest and arranged in a vertical column. The leaves are arranged in increasing order out from the appropriate stems.

Shows each interval of values as a bar. The heights of the bars show the frequencies or relative frequencies of values in each interval.

The mean of a distribution of quantitative data is the average of all the individual data values. To find the mean, add all the values and divide by the total number of data values.

A number that describes some characteristic of a sample.

A number that describes some characteristic of a population.

A statistical measure is resistant if it isn't sensitive to extreme values.

The midpoint of a distribution, the number such that about half the observations are smaller and about half are larger. To find the median, arrange the data values from smallest to largest. — If the number n of data values is odd, the median is the middle value in the ordered list.; If the number n of data values is even, use the average of the two middle values in the ordered list as the median.

The range of a distribution is the distance between the minimum value and the maximum value. That is, Range = Maximum - Minimum

Measures the typical distance of the values in a distribution from the mean. It is calculated by finding an average of the squared deviations and then taking the square root.

The average squared deviation.

The quartiles of a distribution divide the ordered data set into four groups having roughly the same number of values. To find the quartiles, arrange the data values from smallest to largest and find the median.

The first quartile Q1 is the median of the data values that are to the left of the median in the ordered list.

The third quartile Q3 is the median of the data values that are to the right of the median in the ordered list.

The distance between the first and third quartiles of a distribution. In symbols: IQR = Q3 - Q1

The five-number summary of a distribution of quantitative data consists of the minimum, the first quartile Q1, the median, the third quartile Q3, and the maximum.

A visual representation of the five-number summary.

Outliers, Peaks, Gaps

Mean/X bar, Median

Range, Standard Deviation, Variance

Skewed right/left, Symmetric, Unimodal, Bimodal

Mean is greater than median

Mean less than the median