code: function() {
  			// Get the x and y coordinates
  			var xCoords = this.pluck('x');
  			var yCoords = this.pluck('y');
  
  			// Get the means for the x and y coordinates
  			var meanX = xCoords.mean();
  			var meanY = yCoords.mean();
  
  			// Get the standard deviations for the x and y coordinates
  			var stdDevX = xCoords.stdDev();
  			var stdDevY = yCoords.stdDev();
  
  			// Map each element to the difference of the element and the mean
  			// divided by the standard deviation
  			xCoords.map(function(num) {
  				return (num - meanX) / stdDevX;
  			});
  			yCoords.map(function(num) {
  				return (num - meanY) / stdDevY;
  			});
  
  			// Multiply each element in the x by the corresponding value in
  			// the y
  			var nums = this.clone().map(function(num, index) {
  				return xCoords.get(index) * yCoords.get(index);
  			});
  
  			// r is the sum of xCoords over the number of points minus 1
  			return nums.sum() / (nums.size() - 1);
  		}
docs: Calculates the correlation coefficient for the data set.  Returns the value of r.