Chapter 4 Missing values

Observed that volatility and return contains missing values. Take a look into number of missing value in columns we found:

## volatility     return     crypto      price       date    capital     volume 
##         75          5          0          0          0          0          0 
##       year      month 
##          0          0

Calculating volatility requires 15 days data beforehand and return need 1 day data beforehand. Thus each cryptocurrency return variable missed one rows and volatility missed 15 rows of data. In total we have 75 volatility values and 5 return values missing.