2025-10-19

library(ggplot2)
library(plotly)
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Summary

-Simple Linear Regression

–Predicting volume of the tree from its girth

–The data set we will be using is “Trees” which is already built into Rstudio

The formula we will be using

\[ y = \beta_0 + \beta_1x + \epsilon \]

The data we will be using

Here is the dataset that we will be using

head(trees)
##   Girth Height Volume
## 1   8.3     70   10.3
## 2   8.6     65   10.3
## 3   8.8     63   10.2
## 4  10.5     72   16.4
## 5  10.7     81   18.8
## 6  10.8     83   19.7

Scatter Plot

This plot shows how the volume of the tree changes with the girth of the tree.

ggplot(trees, aes(x = Girth, y = Volume)) + geom_point(color = "Green") + labs(title = "Volume Vs Girth of Tree", x = "Girth (Inches)", y = "Volume (Cubic Feet)")

Regression line

This graph shows the linear regression in our dataset

ggplot(trees, aes(x = Girth, y = Volume)) + geom_point()+ geom_smooth(method = "lm", se = F, color = "red") + labs(title = "Linear regression for volume vs girth", x = "Girth (Inches)", y = "Volume (Cubic feet)")
## `geom_smooth()` using formula = 'y ~ x'

3D Plot

This is a 3D plot that shows how volume, height, and girth are related.

plot_ly(trees, x = ~Girth, y = ~Height, z = ~Volume, type = "scatter3d", mode = "markers", marker = list(color = ~Volume, colorscale = "Blues"))

R code example

Here is an example of the R code i used in the previous slides

ggplot(trees, aes(x = Girth, y = Volume)) + geom_point(color = "Green") + labs(title = "Volume Vs Girth of Tree", x = "Girth (Inches)", y = "Volume (Cubic Feet)")

Conclusion

In this presentation i showed a simple linear regression that predicts the volume of a tree by its girth. We accomplished this by using the data set “trees” which is imbeded in rstudio.

This showed me that while girth increases then volume will also increase aswell.

I used a simple linear regression because it shows us how one variable can affect another variable.