Question

In one study (Hedrick et al., 1993), researchers compared the number of motorcycle fatalities that occurred before helmets were mandatory, after helmets were mandatory, and after the helmet laws were repealed. This study used an ______ format with the interrupted time-series design.

Answer 1

This approach likely involved a quasi-experimental or observational format to assess policy impact over time.

Step-by-step explanation:

In the study by Hedrick et al. (1993) which looked at motorcycle fatalities before and after helmet laws were changed, the research is focused on comparing proportions—specifically, the proportion of driver dummies that would have suffered head injuries. An interrupted time-series design is used, which is suited for observations of an outcome over time and monitoring the impact of an intervention, in this case, the implementation and repeal of helmet laws. Given the context, the missing word in the student's question is likely 'quasi-experimental' or 'observational', as these designs are commonplace in policy impact research.

Health and safety researchers often use such designs to assess the efficacy of safety measures, such as bicycle helmets, which are known to 'help protect from head injuries'. Similarly, in the context of the NFL and NCAA, examining the effects of different types of helmets on player safety is a comparable application of assessing interventions over time. A study on the safety of Harley-Davidson motorcycles can follow a similar statistical approach, conducting tests to determine if the proportion of stolen motorcycles differs significantly from expected proportions based on market share.

Lastly, the assessment of changes in safety ratings over the years, analyzing tables for top safety picks in car categories, and the installation of a traffic signal due to reported accidents are all examples of addressing public safety through policy changes and statistical analysis.

Answer 2

Independent groups design format

Step-by-step explanation:

In this example there is only a single variable and it is the number of persons that were not selected specifically for the study. These groups are not equivalent in age, sex, etc and they are from different residential areas and of varying health and ethnic background.

The essence of these tests is to design a single hypothesis over a single variable. In this case wearing or not wearing a motorcycle helmet. It has been found in multiple places that the incidences of road traffic accident deaths reduced with wearing helmets.

Since there was a strong correlation between these two data sets it can be said that they are influenced by each other.