title: How to find correlation coefficients for non-numeric variables
body: <pre><code>Species     Gender     Weight     Corneal Diameter Avg
  Great Grey    M         971            19.5
  Great Grey    F         1209           19.0
  Great Grey    M         952            20.5
  Great Grey    F         1793           20.5
  Snowy         M         1658           22.0
  Snowy         F         1899           22.75
  Snowy         F         1975           24.50
  Snowy         M         1646           23.00
  </code></pre>
  
  <p>Okay so I have this data set. I want to see if there is a correlation between Male Corneal Diameter Average vs. Female Corneal Diameter Average. I'm not sure how I would do this in R. I tried to create a subset for males and females and then use cor(x, y) to get the correlation coefficient but it's not working. Any help would be appreciated! </p>