相关软件（R代码）

# 单样本t检验
# 检验某药物是否使血压平均降低10 mmHg
blood_pressure <- c(145, 142, 138, 140, 148, 135, 139, 141, 136, 143,
                    137, 144, 140, 138, 142, 139, 141, 137, 143, 140)
# H0: mu = 150 (假设原血压均值150), H1: mu != 150
t.test(blood_pressure, mu = 150)
# 两独立样本t检验（Welch's t检验，默认）
group_A <- c(18.3, 19.3, 24.7, 20.2, 20.4, 25.1, 21.4, 16.2, 17.9, 18.7)
group_B <- c(13.0, 20.4, 24.4, 7.3, 21.1, 21.5, 16.1, 16.3, 16.2, 14.5)
t.test(group_A, group_B)  # 默认var.equal=FALSE
# 配对t检验
before <- c(152, 153, 155, 146, 166, 160, 141, 152, 151, 151)
after <- c(150, 135, 146, 142, 140, 150, 141, 129, 127, 137)
t.test(before, after, paired = TRUE)
# 计算效应量（Cohen's d）
# 效应量衡量差异的实际重要性，不仅仅是统计显著性
cohens_d <- function(x, y) {
  mean_diff <- mean(x) - mean(y)
  pooled_sd <- sqrt((var(x) + var(y)) / 2)
  return(mean_diff / pooled_sd)
}
cohens_d(group_A, group_B)

2.2.5 方差分析