Some queries I could think off...

For dataset, 2014/2015 in EPL.

1. How many referees had participated in the league?
    Syntax : distinct(select(datasetname,columnname))
    E.g      : View(distinct(select(fd,Referee)))

   To use this function, however you have to install the dplyr package. 

2. How many times did referee 'P Dowd' serve as the referee?
    Syntax : nrow(datasetname[datasetname$columnname == 'Column value',]) 
    E.g :      nrow(fd[fd$Referee=='P Dowd',])
   Ans : 21
A common mistake would be missing out the comma after entering the Column value.

3. How many times did referee 'M Dean' serve as the referee for Arsenal matches?
    View(filter(fd,Referee=='P Dowd',fd$HomeTeam=='Arsenal'))

4. Which referee served most number of matches for Chelsea?
     Take the list of referees -> find out how many times each referee served for Chelsea when Chelsea played at home and when Chelsea played away.
         Work in progress... please let me know if you have a solution