ChiSquareDistribution.Rmd

---
title: "Chi Square Distribution"
output: html_notebook
---

### Let's draw standard normal distribution N(0,1)
```{r}
curve(dnorm(x), xlim=c(-5,5),ylim=c(0,0.6),ylab="Standard Normal Dist.")
legend(2.5,0.3,c("mean=0, std=1"))
```



### Let's compare normal and Chi-square distribution with d.f. = 1

```{r}
curve(dnorm(x), xlim=c(-2,8),ylim=c(0,1.2),ylab="Normal and Chi Square Dist.")
curve(dchisq(x,1), col="red", lty=2, add=TRUE)
legend(5,0.8,c("Normal", "Chi.Sq d.f.=1"), col=c("black", "red"),lty=1:2)
```


It is referred by http://courses.atlas.illinois.edu/fall2016/STAT/STAT200/RProgramming/NormalChisqT.html



### Let's draw Chi-Sqaure Distribution

```{r}
curve(dchisq(x,1),xlim=c(0,15),ylim=c(0,0.6),ylab="Chi Square Density")
curve(dchisq(x,2),col="red",lty=2,add=TRUE)
curve(dchisq(x,3),col="blue",lty=3,add=TRUE)
curve(dchisq(x,5),col="dark green",lty=4,add=TRUE)
curve(dchisq(x,10),col="brown",lty=5,add=TRUE)
legend(12,0.55,c("k=1","k=2","k=3","k=5","k=10"),
       col=c("black","red","blue","dark green","brown"),lty=1:5)
```