type

Data Type Examples

The “chickwts” is a list of individual observations for each chicken’s weight and feed. It is a cross-sectional data because it only consist of individual observations of a sample at a specific time: after all the eggs hatched into chicken. We can see the data set can be graphed into a scattered plot:

library(AER) 

Loading required package: car

Loading required package: carData

Loading required package: lmtest

Loading required package: zoo

Attaching package: 'zoo'

The following objects are masked from 'package:base':

    as.Date, as.Date.numeric

Loading required package: sandwich

Loading required package: survival

data(chickwts)   
plot(chickwts$weight, chickwts$feed,       main = "Chickwts Scatterplot",      xlab = "Weight",       ylab = "Feed",       pch = 19)

The “euro” is a list of conversion rates between Euro and other European currencies before the adoption of Euro: Austrian Schilling (ATS), Belgian Franc (BEF), German Mark (DEM), Spanish Peseta (ESP), Finnish Markka (FIM), French Franc (FRF), Irish Punt (IEP), Italian Lira (ITL), Luxembourg Franc (LUF), Dutch Guilder (NLG), Portuguese Escudo (PTE). It is a cross-sectional data because it only consist of individual observations of a sample at a specific time: December 31, 1998. We can view the data in a scatter plot:

library(graphics) 
dotchart(euro,          main = "Euro Conversion Rate by Currencies",          pch = 19)