solution-exercise6.Rmd

---
title: "Exercise 6"
author: "Your Name"
date: '`r format(Sys.time(), "%d %b %Y")`'
output: pdf_document
---

First reading the data and doing an initial scatter plot

```{r}
weather <- read.csv("ozone.csv")
plot(weather$Temp, weather$Ozone,xlab="Temperature",ylab="Ozone level",pch=16)
```

Fitting the model using the R formula syntax

```{r}
mod1 <- lm(weather$Ozone~weather$Temp)
summary(mod1)
```

Showing the best-line fit on the plot

```{r}
plot(weather$Temp, weather$Ozone, pch=16)
abline(mod1, col="red", lty=2)
```


```{r}
plot(weather$Temp, weather$Ozone, pch=16)
abline(mod1, col="red", lty=2)
coeffs = coef(mod1)
text(60,150, paste("y = ", round(coeffs[2],2), "x",round(coeffs[1],2),sep=""))
```

Calculating the correlation using the `cor` function and putting the r-squared value on the graph

```{r}
plot(weather$Temp, weather$Ozone, pch=16)
abline(mod1, col="red", lty=2)
cor = cor(weather$Temp,weather$Ozone,use="complete.obs")
cor
text(95,150, paste("r^2 = ", round(cor^2,2)))
```

A little magic to make the formatting a bit nicer

```{r}
plot(weather$Temp, weather$Ozone, pch=16)
abline(mod1, col="red", lty=2)
cor = cor(weather$Temp,weather$Ozone,use="c")
cor
text(95,150, substitute(paste(r^2, "=" ,x),list(x=round(cor^2,2))))
```