title: Removing NA in dplyr pipe
body: <p>I tried to remove NA's from the subset using dplyr piping. Is my answer an indication of a missed step. I'm trying to learn how to write functions using dplyr:</p>
  
  <pre><code>&gt; outcome.df%&gt;%
  + group_by(Hospital,State)%&gt;%
  + arrange(desc(HeartAttackDeath,na.rm=TRUE))%&gt;%
  + head()
  Source: local data frame [6 x 5]
  Groups: Hospital, State
  </code></pre>
  
  <pre>
                             Hospital State HeartAttackDeath
  1     ABBEVILLE AREA MEDICAL CENTER    SC               NA
  2        ABBEVILLE GENERAL HOSPITAL    LA               NA
  3      ABBOTT NORTHWESTERN HOSPITAL    MN             12.3
  4   ABILENE REGIONAL MEDICAL CENTER    TX             17.2
  5        ABINGTON MEMORIAL HOSPITAL    PA             14.3
  6 ABRAHAM LINCOLN MEMORIAL HOSPITAL    IL               NA
  Variables not shown: HeartFailureDeath (dbl), PneumoniaDeath
    (dbl)
  </pre>