title: Remove rows with zero-variance in R
body: <p>I have a dataframe of survey responses (rows = participants, columns = question responses). Participants would respond to 50 questions on a 5-point Likert scale. I would like to remove participants who answered 5 across the 50 questions as they have zero-variance and likely to bias my results.</p>
  
  <p>I have seen the nearZeroVar()function, but was wondering if there's a way to do this in base R?</p>
  
  <p>Many thanks, </p>
  
  <p>R</p>