Correlación

En el análisis de estudios ecológicos, silvícolas, surge frecuentemente la necesidad de determinar la relación entre dos variables cuantitativas en un grupo de sujetos.

Altura vs diámetro Diámetro vs Diámetro de copa

revisar la dispecsión de datos

data(airquality)
head(airquality)

##   Ozone Solar.R Wind Temp Month Day
## 1    41     190  7.4   67     5   1
## 2    36     118  8.0   72     5   2
## 3    12     149 12.6   74     5   3
## 4    18     313 11.5   62     5   4
## 5    NA      NA 14.3   56     5   5
## 6    28      NA 14.9   66     5   6

names(airquality)

## [1] "Ozone"   "Solar.R" "Wind"    "Temp"    "Month"   "Day"

Revisar los datos

plot(airquality$Temp, airquality$Ozone)

boxplot(airquality$Temp)

boxplot(airquality$Ozone, horizontal=T, col="gray", xlab="cantidad de ozono", main="Meses")

plot(airquality$Ozone)

plot(airquality$Solar.R, airquality$Temp)

cor.test(airquality$Solar.R, airquality$Temp)

## 
##  Pearson's product-moment correlation
## 
## data:  airquality$Solar.R and airquality$Temp
## t = 3.444, df = 144, p-value = 0.0007518
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  0.1187 0.4195
## sample estimates:
##    cor 
## 0.2758

cor.test(airquality$Temp, airquality$Wind)

## 
##  Pearson's product-moment correlation
## 
## data:  airquality$Temp and airquality$Wind
## t = -6.331, df = 151, p-value = 2.642e-09
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  -0.5749 -0.3228
## sample estimates:
##    cor 
## -0.458

plot(airquality$Temp, airquality$Wind)

cor.test(airquality$Temp, airquality$Ozone)

## 
##  Pearson's product-moment correlation
## 
## data:  airquality$Temp and airquality$Ozone
## t = 10.42, df = 114, p-value < 2.2e-16
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  0.5913 0.7812
## sample estimates:
##    cor 
## 0.6984

airquality.2 <-subset(airquality, Ozone < 100)
head(airquality.2)

##   Ozone Solar.R Wind Temp Month Day
## 1    41     190  7.4   67     5   1
## 2    36     118  8.0   72     5   2
## 3    12     149 12.6   74     5   3
## 4    18     313 11.5   62     5   4
## 6    28      NA 14.9   66     5   6
## 7    23     299  8.6   65     5   7

plot(airquality.2$Temp, airquality.2$Ozone)

cor.test(airquality.2$Temp, airquality.2$Ozone)

## 
##  Pearson's product-moment correlation
## 
## data:  airquality.2$Temp and airquality.2$Ozone
## t = 12.72, df = 107, p-value < 2.2e-16
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  0.6883 0.8413
## sample estimates:
##    cor 
## 0.7759