==== 独立组总体均值差异的估计 (Estimates of population mean differences among independent groups) ====
  * 用样本均值差去估计总体均值差
  * Using sample mean difference to estimate population mean difference

  * 两个独立样本的置信区间估计:
  * Confidence interval estimation for two independent samples
  * {{::独立样本t置信区间估计.png?200|}}