effectSizeCI {reproducer}

effectSizeCI

Description

95 The procedure is based on finding the upper and lower 0.025 bounds for the related t-variable. The t-variable needs to be adjusted for bias by multiplying by c The upper and lower bounds on the t-variable are then used to calculate to upper and lower bounds on the repeated measures effect size (d_RM) by multiplying the upper and lower bound of the t-variable by sqrt((n1+n2)/(2*(n1*n2))). Upper and lower bounds on the equivalent independent groups effect size (d_IG) are found by multiplying the upper and lower bounds on d_RM by sqrt(1-r).

Usage

effectSizeCI(
  expDesign,
  t,
  n1,
  n2,
  r = 0,
  epsilon = 1e-10,
  maxsteps = 1000,
  stepsize = 3
)

Arguments

expDesign

Experimental design: 1) crossover repeated measures ('CrossOverRM'), 2) before-after repeated measures (expDesign=='BeforeAfterRM'), 3) independent groups ('IG)

t

t-statistics (t must be less than or equal to 37.62, the limit from the R function documentation)

n1

The number of observations in sequence group 1 (expDesign=='CrossOverRM'), the number of observations in group 1 (expDesign=='IG'), or the total number of observations (expDesign=='BeforeAfterRM')

n2

The number of observations in sequence group 2 (expDesign=='CrossOverRM') or the number of observations in group 2 (expDesign=='IG')

r

The correlation between outcomes for individual subject (the within subject correlation)

epsilon

The precision of the iterative procedure

maxsteps

The maximum number of steps of the iterative procedure (the procedure terminates at maxsteps or earlier if CI with enough precision have been calculated)

stepsize

The size of steps (influences the convergence of the calculations, i.e., the number of steps required to obtain the final result of precision defined by the epsilon)

Value

A list of Confidence Intervals for: t-statistic (t_LB and t_UB), repeated-measures effect size d_RM (d_RM_LB, d_RM_UB), independent groups effect size (d_IG_LB, d_IG_UB)

Author(s)

Lech Madeyski and Barbara Kitchenham

Examples

effectSizeCI(expDesign = "CrossOverRM", t = 14.4, n1 = 15, n2 = 15, r = 0.6401)
effectSizeCI(expDesign = "BeforeAfterRM", t = 14.16536, n1 = 15, n2 = 0, r = 0.6146771)
effectSizeCI(expDesign = "IG", t = -6.344175, n1 = 15, n2 = 15)
effectSizeCI(expDesign = "CrossOverRM", t = 0.5581, n1 = 6, n2 = 6, r = 0.36135)
effectSizeCI(expDesign = "CrossOverRM", r = 0.855, t = 4.33, n1 = 7, n2 = 6)