• Goal: Explore how fuel efficiency (mpg) relates to basic car characteristics.
• Tool: Shiny web application built in R.
• Data: Built-in mtcars dataset (32 cars, multiple features).
• Audience: Anyone who wants a quick, interactive view of how car features like weight and horsepower relate to fuel efficiency.

Problem

• Many newcomers to R don’t have an easy, interactive way to:
  • See how mpg changes with other variables.
  • Understand basic linear regression visually.
• Static plots and printed model summaries can be confusing.

Idea

• Build a simple Shiny app that:
  • Lets users choose an X variable (wt, hp, disp).
  • Filters cars by number of cylinders (4, 6, 8).
  • Optionally adds a regression line to summarize the trend.

User Inputs (UI)

• X-axis variable
  • Weight (wt), Horsepower (hp), or Displacement (disp).
• Cylinders to include
  • 4, 6, and/or 8 cylinders.
• Regression line toggle
  • Checkbox: show or hide a fitted linear model.

Outputs (Server)

• Reactive filtering of mtcars based on selected cylinders.
• Scatterplot of mpg vs chosen X variable.
• Optional regression line showing linear trend.
• Printed model summary from lm(mpg ~ X) for the filtered data.

Below is a simple example of R code that mimics part of what the app does. This code is executed when the presentation is rendered.

data(mtcars)

model <- lm(mpg ~ wt, data = mtcars)

summary(model)

## 
## Call:
## lm(formula = mpg ~ wt, data = mtcars)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -4.5432 -2.3647 -0.1252  1.4096  6.8727 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  37.2851     1.8776  19.858  < 2e-16 ***
## wt           -5.3445     0.5591  -9.559 1.29e-10 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 3.046 on 30 degrees of freedom
## Multiple R-squared:  0.7528, Adjusted R-squared:  0.7446 
## F-statistic: 91.38 on 1 and 30 DF,  p-value: 1.294e-10

Thanks for reviewing my presentation and app!