Insurance injury ratings of Chevrolet vehicles for 1990 and 1993 models

Data for Exercise 8.35

Chevy

Format

A data frame/tibble with 67 observations on two variables

year

a factor with levels 1988-90 and 1991-93

frequency

a factor with levels much better than average, above average, average, below average, and much worse than average

Source

Insurance Institute for Highway Safety and the Highway Loss Data Institute, 1995.

References

Kitchens, L. J. (2003) Basic Statistics and Data Analysis. Pacific Grove, CA: Brooks/Cole, a division of Thomson Learning.

Examples

T1 <- xtabs(~year + frequency, data = Chevy)
T1
#>          frequency
#> year      much better than average above average average below average
#>   1988-90                       16             5       5             3
#>   1991-93                       12             2      12             2
#>          frequency
#> year      much worse than average
#>   1988-90                       4
#>   1991-93                       6
chisq.test(T1)
#> Warning: Chi-squared approximation may be incorrect
#> 
#> 	Pearson's Chi-squared test
#> 
#> data:  T1
#> X-squared = 5.3258, df = 4, p-value = 0.2555
#> 
rm(T1)