siteaddr <- "http://www.karlin.mff.cuni.cz/~pesta/NSTP097"
datafile <- paste(siteaddr,"cvic_k10_4.RData",sep="/")
load(url(datafile))

names(plat)
summary(plat)
attach(plat)
hist(mzda)

table(jih)
tapply(mzda,jih,mean)
tapply(mzda,jih,var)
tapply(mzda,jih,skewness)

boxplot(split(mzda,jih))

par(mfrow=c(2,1))
hist(mzda[jih=="Jih"],breaks=5*(0:10),xlim=range(mzda))
hist(mzda[jih=="jinde"],breaks=5*(0:10),xlim=range(mzda))
par(mfrow=c(1,1))

a <- ecdf(mzda[jih=="Jih"])
b <- ecdf(mzda[jih=="jinde"])
oddo <- range(mzda)*c(0.9,1.1)
par(col="blue")
plot(a,xlim=oddo,main="Empiricka distribucni funkce mzdy",cex=0.3)
par(col="black")
lines(b,cex=0.3,lty=2)
legend(30,0.4,lty=c(1,1),col=c("blue","black"),legend=c("Jih","Jinde"))

ks.test(mzda[jih=="Jih"],mzda[jih=="jinde"])
t.test(x=mzda[jih=="Jih"],y=mzda[jih=="jinde"],var.equal=T)
t.test(x=mzda[jih=="Jih"],y=mzda[jih=="jinde"],var.equal=F)
wilcox.test(mzda[jih=="Jih"],mzda[jih=="jinde"])
sum(rank(mzda)[jih=="Jih"])

t.test(x=log10(mzda)[jih=="Jih"],y=log10(mzda)[jih=="jinde"],var.equal=T)
t.test(x=log10(mzda)[jih=="Jih"],y=log10(mzda)[jih=="jinde"],var.equal=F)


table(rasa)

boxplot(mzda~rasa)

par(mfrow=c(3,1))
hist(mzda[rasa=="Beloch"],breaks=5*(0:10),xlim=range(mzda))
hist(mzda[rasa=="Hispanik"],breaks=5*(0:10),xlim=range(mzda))
hist(mzda[rasa=="Jina"],breaks=5*(0:10),xlim=range(mzda))
par(mfrow=c(1,1))

tapply(mzda,rasa,mean)
tapply(mzda,rasa,var)

summary(aov(mzda~rasa))

1-pf(3.2969,2,531)
qf(0.95,2,531)


boxplot(log10(mzda)~rasa)

par(mfrow=c(3,1))
hist(log10(mzda)[rasa=="Beloch"],xlim=range(log10(mzda)))
hist(log10(mzda)[rasa=="Hispanik"],xlim=range(log10(mzda)))
hist(log10(mzda)[rasa=="Jina"],xlim=range(log10(mzda)))
par(mfrow=c(1,1))

tapply(log10(mzda),rasa,mean)
tapply(log10(mzda),rasa,var)

summary(aov(log10(mzda)~rasa))