Exploratory analysis

expl.R

@@ -2,6 +2,8 @@
 
 # Libraries
 library(ggplot2)
+library(dplyr)
+library(RColorBrewer)
 
 # Load data from Rdata file
 load("crashdata.Rdata")
@@ -9,8 +11,52 @@ load("crashdata.Rdata")
 # Alternative way to load data
 #dat <- read.csv("finaldata_201809.csv")
 
+# Relevel crash severity
+dat$CRASH_SEV <- factor(dat$CRASH_SEV, levels = c("N", "M", "S", "F"))
+
 str(dat)
 
 yeartab <- table(dat$CRASH_YEAR)
+mpy <- mean(yeartab)
+
+# Obviously, data missing from 2018
+ggplot(dat) + geom_bar(aes(x=CRASH_YEAR), fill=NA, col="black") +
+  geom_hline(yintercept = mpy, linetype="dashed") + theme_classic() +
+  labs(x = "Year", y = "Number of crashes")
+table(dat$CRASH_FIN_YEAR)
+
+# Check that severity is given as F if and only if nonzero number of fatalities
+table(dat$CRASH_SEV, dat$FATAL_COUNT)
+
+# Look at number of vehicles involved
+levels(dat$MULTI_VEH)
+table(dat$MULTI_VEH, dat$CRASH_SEV)
+
+# Open road vs vehicles
+vehtab <- table(dat$MULTI_VEH, dat$URBAN, dat$CRASH_SEV == "F")
+vehtab
+
+# Graph crash severity
+ggplot(dat) + geom_bar(aes(x=CRASH_SEV), fill=NA, col="black") +
+  theme_classic() + labs(x = "Crash severity", y = "Number of crashes")
+
+# Not all openroad crashes are on state highways
+table(dat$URBAN, dat$CRASH_SH_DESC)
+
+# Motorcycle crash severity
+table(dat$CRASH_SEV, dat$MOTOR_CYCLE > 0)
+
+# Just look at fatal crashes on the open road on state highways
+rurhwy <- dat %>% filter(URBAN == "Openroad", CRASH_SH_DESC == "Yes")
+frurhwy <- rurhwy %>% filter(CRASH_SEV == "F")
+
+str(frurhwy)
+
+knitr::kable(table(rurhwy$MULTI_VEH, rurhwy$CRASH_SEV))
 
-ggplot(dat) + geom_bar(aes(x=CRASH_YEAR))
+ggplot(rurhwy) + 
+  geom_bar(aes(fill = MULTI_VEH != "Single vehicle", x = CRASH_SEV), position="dodge") +
+  scale_fill_brewer("Vehicles involved", type="qual", palette = "Dark2",
+                      labels = c("Single vehicle", "All other categories")) +
+  scale_x_discrete("Severity", labels = c("Not", "Moderate", "Severe", "Fatal")) +
+  theme_classic() + theme(legend.position = "right")