Objectives

The objectives of this problem set is to orient you to a number of activities in R. And to conduct a thoughtful exercise in appreciating the importance of data visualization. For each question create a code chunk or text response that completes/answers the activity or question requested. Finally, upon completion post your assignment on Rpubs and upload a link to it to the “Problem Set 2” assignmenet on Moodle.

Questions

  1. Anscombes quartet is a set of 4 \(x,y\) data sets that were published by Francis Anscombe in a 1973 paper Graphs in statistical analysis. For this first question load the anscombe data that is part of the library(datasets) in R. And assign that data to a new object called data.

library(datasets) data<-anscombe data

  1. Summarise the data by calculating the mean, variance, for each column and the correlation between each pair (eg. x1 and y1, x2 and y2, etc) (Hint: use the fBasics() package!)

install.packages(“fBasics”) library(“fBasics”)

library(“timeDate”) library(“timeSeries”)

mean(data\(x1) var(data\)x1)

mean(data\(x2) var(data\)x2)

mean(data\(x3) var(data\)x3)

mean(data\(x4) var(data\)x4)

mean(data\(y1) var(data\)y1)

mean(data\(y2) var(data\)y2)

mean(data\(y3) var(data\)y3)

mean(data\(y4) var(data\)y4)

correlationTest(data\(x1,data\)y1)

correlationTest(data\(x2,data\)y2)

correlationTest(data\(x3,data\)y3)

correlationTest(data\(x4,data\)y4)

  1. Create scatter plots for each \(x, y\) pair of data.

plot(data\(x1, data\)y1, main=“Scatterplot between x1,y1”)

plot(data\(x2, data\)y2, main=“Scatterplot between x2,y2”)

plot(data\(x3, data\)y3, main=“Scatterplot between x3,y3”)

plot(data\(x4, data\)y4, main=“Scatterplot between x4,y4”) 4. Now change the symbols on the scatter plots to solid circles and plot them together as a 4 panel graphic

par(mfrow=c(2,2)) plot(data\(x1,data\)y1, main=“Scatterplot between x1,y1”,pch=20) plot(data\(x2,data\)y2, main=“Scatterplot between x2,y2”,pch=20) plot(data\(x3,data\)y3, main=“Scatterplot between x3,y3”,pch=20) plot(data\(x4,data\)y4, main=“Scatterplot between x4,y4”,pch=20)

  1. Now fit a linear model to each data set using the lm() function.

fit1<-lm(data\(y1~data\)x1) fit2<-lm(data\(y2~data\)x2) fit3<-lm(data\(y3~data\)x3) fit4<-lm(data\(y4~data\)x4)

  1. Now combine the last two tasks. Create a four panel scatter plot matrix that has both the data points and the regression lines. (hint: the model objects will carry over chunks!)

par(mfrow=c(2,2)) plot(data\(x1,data\)y1, main=“Scatterplot between x1,y1”,pch=20) abline(fit1, col=“blue”) plot(data\(x2,data\)y2, main=“Scatterplot between x2,y2”,pch=20) abline(fit2, col=“blue”) plot(data\(x3,data\)y3, main=“Scatterplot between x3,y3”,pch=20) abline(fit3, col=“blue”) plot(data\(x4,data\)y4, main=“Scatterplot between x4,y4”,pch=20) abline(fit4, col=“blue”)

  1. Now compare the model fits for each model object.

anova(fit1)

anova(fit2)

anova(fit3)

anova(fit4)

  1. In text, summarize the lesson of Anscombe’s Quartet and what it says about the value of data visualization.

Anscombe’s Quartet is a proof that even when the statistical values of seems to be alike, they can be totally different when graphed.The dataset’s data vizualization helps in understanding the importance of Data Viz and how it helps in better understanding the data.