Example 1.3 from Statistics, 1.1 Definitions of Statistics, Probability, and Key Terms

Definitions of Statistics, Probability, and Key Terms: example 1.3

Determine what the population, sample, parameter, statistic, variable, and data referred to in the following study.

As part of a study designed to test the safety of automobiles, the National Transportation Safety Board collected and reviewed data about the effects of an automobile crash on test dummies (The Data and Story Library, n.d.). Here is the criterion they used.

Speed at which Cars Crashed	Location of Driver (i.e., dummies)
35 miles/hour	Front seat

Table 1.1

Cars with dummies in the front seats were crashed into a wall at a speed of 35 miles per hour. We want to know the proportion of dummies in the driver’s seat that would have had head injuries, if they had been actual drivers. We start with a simple random sample of 75 cars.

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution
The population is all cars containing dummies in the front seat.
The sample is the 75 cars, selected by a simple random sample.

The parameter is the proportion of driver dummies—if they had been real people—who would have suffered head injuries in the population.
The statistic is proportion of driver dummies—if they had been real people—who would have suffered head injuries in the sample.
The variable X = whether driver dummies—if they had been real people—would have suffered head injuries.
The data are either: yes, had head injury, or no, did not.

How did it go?

Solution

Solution