A Python class I wrote to do the boring parts of my Stats homework

stats.py

from math import sqrt

class Stats(object):

	def __init__(self, dataset):
		"""
		A basic statistics class. Takes in a dataset of a list of numbers
		"""
		self.dataset = dataset

	@property
	def mean(self):
		"""
		Returns the mean (average) of the dataset
		"""
		return sum(self.dataset)/float(len(self.dataset))

	@property
	def std_dev(self):
		"""
		Returns the standard deviation for the dataset
		"""
		m = self.mean
		return sqrt((sum([(x-m)**2 for x in self.dataset]))/(len(self.dataset)-1))

	@property
	def range(self):
		"""
		The range of the dataset
		"""
		return max(self.dataset) - min(self.dataset)

	def chebychev(self, k):
		"""
		Returns the chebychev percentage for standard deviation with a given k
		value as a decimal between 1 and 0
		"""
		return 1.00-(1.00/(k**2))

	def chebychev_mean(self, k=1):
		"""
		Returns the percentage of items in the dataset that are within k 
		times of the standard deviation as a decimal between 1 and 0
		"""
		m = self.mean
		sdev = self.std_dev
		bounds = [m-(sdev*k), m+(sdev*k)]
		return len([x for x in dataset if (x >= bounds[0] and x <= bounds[1])])/float(len(dataset))