in Inclement Weather
Research conducted by: Darin
Case study prepared by: Emily
Many people believe
that weather patterns influence driving safety. As a result, there
are many web sites and other publications dedicated to giving people
tips about how to drive in various weather conditions (see references
and links below). Additionally, car accidents are often attributed
to bad weather (e.g., see Taylor & Quinn, 1991). This study
examines the beliefs and behaviors of people with respect to the
important topic of driving in inclement weather.
The participants in this study filled out a questionnaire consisting
of some demographic questions and then questions asking about
their transportation habits and other beliefs concerning inclement
weather. This questionnaire was administered to a convenience
sample of 61 University of Houston - Downtown students at various
locations (i.e., classrooms, hallways, and the food court).
Questions to Answer
or age related to the likelihood of driving in inclement weather?
Does the number of accidents that someone thinks occur during inclement
weather relate to how often he or she takes public transportation
or chooses to drive during inclement weather?
This is a correlational
study, so we cannot infer causation.
Descriptions of Variables
||The age of the participant in years
||1 = female, 2 = male
||How often he or she chooses to drive in inclement weather
1 = always, 3 = sometimes, 5 = never
||% of travel time spent on public transportation in inclement
||% of accidents thought to occur from driving in inclement
Galski, T., Ehle, H. T, & Bradley,
W. J. (1998). Estimates of driving abilities and skills
in different conditions. American Journal of Occupational
Therapy, 52, 268-275.
Griffin, J., & Murdock, G. (1993,
August). Wet weather driving. Consumers' Research Magazine,
Taylor, G. W., & Quinn, H. (1991,
January 14). An arctic winter rage. Maclean's, 104,
on Wet Roads
about Driving in Inclement Weather
- What are the mean and median ages?
- Plot a histogram of the distribution of the ages. Using
this plot and the information from #1, determine if the
age variable is normally distributed, positively skewed,
or negatively skewed.
- What is the mean percentage of time that the participants
in this study spend traveling on public transportation
during inclement weather?
- What is the standard deviation of Pubtran?
- What is the correlation between age and how often the
person chooses to drive in inclement weather? Is this
correlation statistically significant at the .01 level?
Are older people more or less likely to report that they
drive in inclement weather?
- Compute a 95% confidence interval on the correlation
between age and how often the person chooses to drive
in inclement weather.
- Is there a gender difference in the likelihood to drive
in inclement weather? Do the following exercises to find
- Plot side-by-side (parallel) box plots of Cho2drive
- What is the mean difference in how much men and
women choose to drive in inclement weather?
- Perform an independent samples t test.
- Is there any evidence that the assumption of homogeneity
of variance is violated?
- What is the 95% confidence interval for the mean
- Can you reject the null hypothesis if α
- What is the correlation between how often a person chooses
to drive in inclement weather and the percentage of accidents
the person believes occur in inclement weather? Is this
correlation significantly different from 0?
- What is the correlation between how often someone rides
public transportation in inclement weather (Pubtran) and
what percentage of accidents the person thinks occur in
inclement weather (Accident)?
- Use linear regression to predict how often someone rides
public transportation in inclement weather from what percentage
of accidents that person thinks occur in inclement weather.
(Pubtran by Accident)
- Create a scatter plot of this data and add a regression
- What is the slope?
- What is the intercept?
- Is the relationship at least approximately linear?
- Test if the slope is significantly different from
- Comment on possible assumption violations for the
test of the slope.
- What is the standard error of the estimate?