ttest: Student and Welch t Tests

In R4VN: Health Data Analysis and Publication-Ready Reporting

Student and Welch t Tests

Description

ttesti() calculates one- or two-sample t tests from summary statistics. ttest() performs the same analysis from variables and reports group sample size, mean, standard error, standard deviation, and confidence interval. ttest(..., effect = TRUE) additionally reports Cohen's d and Hedges' g. With by = vars(province, sex, treatment), province and sex are nested strata and treatment is the innermost two-group comparison.

Usage

ttesti(
  n1,
  mean1,
  sd1,
  n2 = NULL,
  mean2 = NULL,
  sd2 = NULL,
  mu = 0,
  equal = FALSE,
  paired = FALSE,
  r = NULL,
  alternative = c("two.sided", "less", "greater"),
  level = 0.95,
  digits = 3,
  p_digits = 3,
  show = TRUE,
  console = FALSE
)

ttesti(
  n1, mean1, sd1, n2 = NULL, mean2 = NULL, sd2 = NULL, mu = 0, equal = FALSE,
  paired = FALSE, r = NULL, alternative = c("two.sided", "less", "greater"),
  level = 0.95, digits = 3, p_digits = 3, show = TRUE, console = FALSE
)

ttest(
  x, y = NULL, by = NULL, data = NULL, mu = 0, equal = FALSE, paired = FALSE,
  alternative = c("two.sided", "less", "greater"), level = 0.95,
  effect = FALSE, digits = 3, p_digits = 3, show = TRUE, console = FALSE
)

ttest(
  x,
  y = NULL,
  by = NULL,
  data = NULL,
  mu = 0,
  equal = FALSE,
  paired = FALSE,
  alternative = c("two.sided", "less", "greater"),
  level = 0.95,
  effect = FALSE,
  digits = 3,
  p_digits = 3,
  show = TRUE,
  console = FALSE
)

Arguments

n1, mean1, sd1	Sample size, mean, and standard deviation for group 1.
n2, mean2, sd2	Optional sample size, mean, and standard deviation for group 2.
mu	Null mean or null mean difference.
equal	Use the equal-variance two-sample t test.
paired	Perform a paired analysis.
r	Correlation between paired measurements when only summaries are available.
alternative	Alternative hypothesis: "two.sided", "less", or "greater".
level	Confidence level as a proportion.
digits, p_digits	Decimal places for estimates and p-values.
show	Logical; open the formatted result in the Viewer. Default TRUE.
console	Logical; also print the traditional text result in the Console. Default FALSE.
x, y	Numeric variables. y is optional.
by	Optional two-level grouping variable. by = vars(a, b, group) performs the test within nested a > b strata using group as the innermost comparison.
data	Data frame. If NULL, the active data set is used.
effect	Logical; for ttest(), add standardized effect sizes.

Value

Invisibly returns an object of class r4vn_stat.

Examples

ttesti(40, 12, 3, mu = 10)
ttesti(40, 12, 3, 35, 14, 4)

d <- data.frame(score = c(10,12,11,18,17,20,9,13,12,19,21,18),
                treatment = rep(c("Control","Intervention"), each = 6),
                province = rep(c("A","B"), each = 3, times = 2))
ttest(score, by = treatment, data = d, effect = TRUE)
ttest(score, by = vars(province, treatment), data = d, effect = TRUE)

R4VN documentation built on Sept. 30, 2026, 5:13 p.m.