It is common to find yourself needing to use specific symbols or mathematical notation on R graphics. For example you may want to display R^2 values, but you also want the R^2 to be rendered nicely.

R has a rich set of options for including this mathematical text on plots. We previously discussed this in a tutorial.

Answers to the exercises are available here.

**Exercise 1**

Load the *LakeHuron* data set using the `data()`

function. This data includes the lake’s water depth in feet each year from 1875—1972.

**Exercise 2**

Plot Lake Huron water depth over time. Also use `lm()`

to run a linear model and plot a best fit line. Also, use `summary()`

to look at the model fit.

**Exercise 3**

Use `str()`

on the previous `summary()`

object to see everything you can extract from the `summary()`

object. Also, be able to extract the model coefficients specifically.

**Exercise 4**

Add text for a linear model (y[i] = alpha + beta*X[i]) on your plot using the `text()`

function combined with `expression()`

and `paste()`

**Exercise 5**

Again, add text detailing a linear model, but use the model coefficients in place of alpha and beta in the previous exercise. You will need to use `substitute()`

here.

**Exercise 6**

Add the R^2 symbol to the plot. Use `expression()`

.

**Exercise 7**

Use `substitute()`

to include the model estimated R^2 on the plot.

**Exercise 8**

In bold text, include R’s notation for a p-value, Pr(>|t|), in the title of the plot.

**Exercise 9**

Use the model estimated p-value for the significance of the slope of the line in the title of the plot.

**Exercise 10**

Use demo(plotmath) or ?plotmath to learn more about using mathematical notation in R

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