Not quite so simple. In statistics, when a datum is too far out in left field, it’s known as an “outlier.” If you have a room of 50 people and you want the average age of all 50, most of whom are in the 30-35 age range, and you have one old geezer who is 85 years old, he doesn’t represent the the average age range and his age, factored in, could skew the results and provide an inaccurate representation of the more obvious reality. Stats operates on “almosts” and “pretty nears” known as “degrees of freedom.” So it would be perfectly legit to eliminate Calvin’s skewed data.
Sometimes it’s wise to use a comma with the “and” at the end of the series. Saying “and” without the comma can sometimes be confused for the last two entries to be combined as one. Ex: The three who went to the movies were Tom, Bobby, and I. To say “Bobby and I” may imply that Bobby and I are together as a unit. If Bobby and I are both males, that might seem a little funny.
Yes, yes it is.