@Test
public void testStdDev() throws Exception {

  Path input = getTestTempFilePath("stdDev/counts.file");
  Path output = getTestTempFilePath("stdDev/output.file");
  
  produceTestData(input);
  
  double v = BasicStats.stdDev(input, output, conf);
  assertEquals(1.56, v, 0.01); //sample std dev is 1.563, std. dev from a discrete set is 1.48
}