d = our data. You could put any kind of data in
d and I'm only using it for the sake of clarity, since these functions are not only working with our data.
1. Check what you are manipulating
What are your variables? And what are their types/values?
str(d): variables types and first 10 values
summary(d): summary for each variable
library('pastecs'): alternative to summary
library('psych'): alternative to summary
head(d)/tail(d): first/last 10 values
View(d): open in the graphical view
names(d): get variables names
dim(...)/length(...): check the length of your sample/variables
unique(...)/duplicated(...): are some values duplicated?
2. Now clean and prepare your sample
Once you have at least some information