Car Stopping Distance in the 1920’s

author: Kathryn Alexander date: 2/17/20 autosize: true

Introduction

What was the stopping distance of cars in the 1920’s?

• The cars data set in R has 50 observations of the variables speed (miles per hour - mph) and distance (feet)
• The data was recorded in the 1920’s
• The maximum speed recorded was 25 mph!

Code for Predictive Model

A linear model is used to predict the car stopping distance (in feet) based on the car speed (in mph). A speed of 20 mph results in a stopping distance of 61.06908 feet.

data(cars)
model1 <- lm(dist ~ speed, data = cars)
model1pred <- predict(model1, newdata = data.frame(speed = 20))
model1pred

       1 
61.06908 

Plot of Car Speed and Stopping Distance

Here is a plot of the data and the linear model that was fit to it. The example of 20 mph is highlighted with a red data point larger than the other data.

plot of chunk unnamed-chunk-2

Try the Shiny App!

Try out the Shiny App to explore the stoppping distance of cars in the 1920’s

• Look at the stopping distance of a car going 30 mph (a real speedster!)
• See the spread of the data, and turn the model prediction on/off
• Have your selected speed highlighted on the plot