AP Statistics 1.2.A Variables, Parameters & Statistics

Practise identifying variables and population parameters from study descriptions, translating the quantity measured and the target summary into context.

Exam points

Name each measured variable with its observational-unit context and units where relevant.
Define the population parameter as a contextual summary, such as a mean over all target units.

An environmental research agency conducted a study of a certain state's roadsides to estimate the mean number

of discarded cans and bottles per mile of public road. The state's public roads were grouped into three types:

Major highways: major paved roads designed for high traffic volume

Minor highways: smaller paved roads designed for low traffic volume

Unpaved roads: gravel and dirt roads

There are about 100,000 miles of public roads in the state. The environmental research agency defined a

sampling unit to be a one-mile segment of public road. Using a database supplied by the state's department of

transportation, the agency randomly selected 30 one-mile road segments for each of the three types of roads.

Researchers from the agency searched the roadsides along each of the selected one-mile road segments and

recorded the number of discarded cans and bottles. Results are shown in the table below.

Table for Question 1.2.A—Identify observational units, variables, parameters, and statistics from a statistical study or data set question 1 — AP Statistics

What is the variable of interest in the study?

What is the parameter of interest?

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1.2.A—Identify observational units, variables, parameters, and statistics from a statistical study or data set question 1