Applying descriptive statistics in R

Fundamentals

data("PlantGrowth")

data <- PlantGrowth
head(data)

##   weight group
## 1   4.17  ctrl
## 2   5.58  ctrl
## 3   5.18  ctrl
## 4   6.11  ctrl
## 5   4.50  ctrl
## 6   4.61  ctrl

str(data)

## 'data.frame':	30 obs. of  2 variables:
##  $ weight: num  4.17 5.58 5.18 6.11 4.5 4.61 5.17 4.53 5.33 5.14 ...
##  $ group : Factor w/ 3 levels "ctrl","trt1",..: 1 1 1 1 1 1 1 1 1 1 ...

by(data, data$group, summary)

## data$group: ctrl
##      weight       group   
##  Min.   :4.170   ctrl:10  
##  1st Qu.:4.550   trt1: 0  
##  Median :5.155   trt2: 0  
##  Mean   :5.032            
##  3rd Qu.:5.293            
##  Max.   :6.110            
## ------------------------------------------------------------ 
## data$group: trt1
##      weight       group   
##  Min.   :3.590   ctrl: 0  
##  1st Qu.:4.207   trt1:10  
##  Median :4.550   trt2: 0  
##  Mean   :4.661            
##  3rd Qu.:4.870            
##  Max.   :6.030            
## ------------------------------------------------------------ 
## data$group: trt2
##      weight       group   
##  Min.   :4.920   ctrl: 0  
##  1st Qu.:5.268   trt1: 0  
##  Median :5.435   trt2:10  
##  Mean   :5.526            
##  3rd Qu.:5.735            
##  Max.   :6.310

Central Tendency

library(pastecs)

## 
## Attaching package: 'pastecs'

## The following objects are masked from 'package:dplyr':
## 
##     first, last

## The following object is masked from 'package:tidyr':
## 
##     extract

stat.desc(data)

##                   weight group
## nbr.val       30.0000000    NA
## nbr.null       0.0000000    NA
## nbr.na         0.0000000    NA
## min            3.5900000    NA
## max            6.3100000    NA
## range          2.7200000    NA
## sum          152.1900000    NA
## median         5.1550000    NA
## mean           5.0730000    NA
## SE.mean        0.1280195    NA
## CI.mean.0.95   0.2618293    NA
## var            0.4916700    NA
## std.dev        0.7011918    NA
## coef.var       0.1382204    NA

Mean, Median, Mode

Skewness

Variance

Standard Deviation

Covariance

Correlation Coefficient