The Unexpected Relationship between Physical Inactivity and Motor Vehicle Crash Deaths

Eric Huynh
Fall 2023 — Information Expositions
4 min readDec 18, 2023

Delving into the connections between different things in counties can teach us a lot. While we usually expect certain relationships, like how money affects an area, it made me wonder: are there possible relationships between variables we wouldn’t expect to relate to one another? Beyond the usual suspects, I decided to explore an unexpected connection that shape communities. Picture this: a closer look at how staying inactive might have a surprising connection with the frequency of car crashes, specifically among the White population. It’s like being detectives, exploring the less traveled paths in data, which fuels this exploration, propelling us towards a more comprehensive understanding of the factors influencing county-level dynamics.

Data

For this analysis, I looked at U.S county data, using csv files called us_counties and analytic_data2021 available from the Internet Archive’s Wayback Machine. Both datasets contain different variables/statistics covering demographic, health, economic, educational, and social aspects at the county level such as the percentage of people who are high school grads or the raw value (typically refers to the original, unprocessed data or measurement of a particular variable) of alcohol-impaired driving deaths. Merging both datasets together, I examined the different variables and identified possible, unusual relationships that would make sense once a case was made.

Relationship between physical inactivity and motor vehicle crash deaths

The physical inactivity raw value by motor vehicle crash deaths among White population
Correlogram of physical inactivity and motor vehicle crash deaths among White population

We can see that the linear regression line shows the positive relationship between physical inactivity and motor vehicle crash deaths in the first graph; as the physical inactivity raw value increases, the number of vehicle crash deaths increases as well. Furthermore, in the correlogram, a correlation coefficient of 0.51 between the physical inactivity raw value and motor vehicle crash deaths suggests a moderate positive relationship. Again, this value signifies that as the level of physical inactivity increases, there is a tendency for motor vehicle crash deaths to also increase, but the relationship is not exceedingly strong.

Ordinary Least Squares (OLS) regression results for physical inactivity and motor vehicle crash deaths

The second image displays the Ordinary Least Squares (OLS) regression results for physical inactivity and motor vehicle crash deaths. It provides insights into the relationship between physical inactivity and motor vehicle crash deaths. The R-squared value of 0.256 suggests that approximately 25.6% of the variability in physical inactivity can be explained by motor vehicle crash deaths among the White population. The coefficient for Motor_vehicle_crash_deaths_White is 0.0032, indicating that, on average, a one-unit increase in motor vehicle crash deaths among the White population is associated with a 0.0032 unit increase in the raw value of physical inactivity. The p-values for both the intercept and the coefficient are very small (close to 0), suggesting that the relationship is statistically significant. The F-statistic of 868.3 further supports the overall significance of the model. In conclusion, this regression model provides evidence of a statistically significant positive relationship between motor vehicle crash deaths among the White population and physical inactivity at a county level.

Ordinary Least Squares (OLS) regression results for physical inactivity and motor vehicle crash deaths + suicides

To explore even further, I decided to see whether this relationship shows up or disappears in related variables by adding an additional variable, Suicides_raw_value and computing the OLS regression. The intercept is 0.2097, and it represents the estimated physical inactivity when all predictor variables are zero. The coefficient for Suicides_raw_value is -0.0009, suggesting that a one-unit increase in suicides is associated with a decrease of 0.0009 in the physical inactivity raw value. However, our focus is on the relationship with motor vehicles crash deaths and physical inactivity. The coefficient for Motor_vehicle_crash_deaths_White is 0.0041, indicating that a one-unit increase in motor vehicle crash deaths among the White population is associated with a 0.0041 increase in the physical inactivity raw value. This means that there is still a positive relationship between the two variables I previously talked about.

The positive relationship between physical inactivity and motor vehicle crash deaths could be attributed to several factors. One possible explanation is that physically inactive individuals may have poorer overall health and reduced cognitive functioning, leading to diminished reflexes and slower reaction times while driving. Additionally, sedentary lifestyles are often associated with conditions such as obesity and cardiovascular issues, which can contribute to a higher likelihood of accidents or fatalities in motor vehicle crash deaths.

Conclusion

While our initial pursuit sought to unravel the less-explored nuances of data, the positive correlation revealed in both the graphical and statistical analyses reinforces the significance of this peculiar association. The Ordinary Least Squares (OLS) regression results substantiate a statistically significant link, with motor vehicle crash deaths among the White population explaining approximately 25.6% of the variability in physical inactivity at the county level. The positive correlation between physical inactivity and motor vehicle crash deaths prompts reflection on potential contributing factors, such as the impact of sedentary lifestyles on overall health and cognitive function. In the future, I am interested in learning and understanding more about other variables that may not seen to have a relationship at first because revealing unforeseen connections can provide valuable insights and contribute to a more comprehensive understanding of the complexity surrounding the various factors that may influence the root causes of phenomena in diverse contexts.

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