ris {RTSA}

Calculate required sample and trials size.

Description

Calculate required sample and trials size.

Usage

ris(
  outcome,
  mc,
  side = 2,
  alpha = 0.05,
  beta = 0.1,
  fixed = TRUE,
  sd_mc = NULL,
  pC = NULL,
  p1 = NULL,
  ma = NULL,
  tau2 = NULL,
  I2 = NULL,
  D2 = NULL,
  type = "prospective",
  trials = NULL,
  RTSA = FALSE,
  ...
)

Arguments

outcome

Choose between: "MD" (mean difference), "RR" (relative risk), "OR" (odds ratio) or "RD" (risk difference).

mc

Minimum clinical relevant effect. For "OR" or "RR" set to natural scale, not log scale.

side

Test type. Set to 1 or 2 depending on the test being 1- or 2-sided.

alpha

The level of type I error as a percentage, the default is 0.05 corresponding to 5%.

beta

The level of type II error as a percentage, the default is 0.1 corresponding to 10%.

fixed

Should sample size be based on a fixed-effect (TRUE) or random-effects (FALSE) model. Defaults to TRUE.

sd_mc

Standard deviation of estimated effect. Only needed when outcome type is "MD".

pC

Probability of event in control group. Only needed when outcome type is "OR", "RR" or "RD".

p1

Probability of event in treatment group. Only needed when outcome type is "RD".

ma

An optional metaanalysis object. Required for retrospective sample size calculations.

tau2

The value of the heterogeneity. Use when estimating the sample size under a random effects model. If data is provided, the estimated heterogeneity is used instead.

I2

Optional argument. Inconsistency.

D2

Optional argument. Diversity.

type

Whehter the type of calculaiton is for "prospective" meta-analysis or "retrospective" meta-analysis. If the type is retrospective, one should add a meta-analysis object to the function. See argument ma.

trials

Optional numeric argument. If one is interested in a specific number of trials.

RTSA

Whether the ris function was called via the RTSA function. Purely operational argument.

...

additional arguments

Value

A list of up to 6 elements:

settings

A list containing the arguments provided to the ris function.

NF

The total number of required participants in a fixed-effect meta-analysis if type is prospective. Contains a list if the type is retrospective, where NF is the additional required number of participants and NF_full is the total required number of participants.

NR_tau

A list containing: minTrial the minimum number of trials. nPax a matrix containing four possible number of trials with the number of participants per trial and total number of participants. tau2 the estimate used for the calculation. Might contain NR_tau_ll and NR_tau_ul which contain the same three elements. NR_tau_ll is based on the lower value in the confidence interval of tau2. NR_tau_ul is based on the upper value in the confidence interval for tau2. If the type is prospective the numbers are the total required. If the type is retrospective the numbers are the additional required.

NR_D2

The total number of required participants in a random-effects meta-analysis adjusted by diversity (D2) if type is prospective. Contains a list if the type is retrospective, where NR_D2 is the additional required number of participants and NR_D2_full is the total required number of participants.

NR_I2

The total number of required participants in a random-effects meta-analysis adjusted by inconsistency (I2) if type is prospective. Contains a list if the type is retrospective, where NR_I2 is the additional required number of participants and NR_I2_full is the total required number of participants.

Examples

# Sample and trial size calculation for prospective meta-analysis
ris(outcome = "RR", mc = 0.8, pC = 0.12, fixed = TRUE, alpha = 0.05,
beta = 0.1, side = 2)

# Additional sample and trial size calculation for retrospective meta-analysis 
# It is calculated directly from the metaanalysis() function
data("perioOxy")
ma <- metaanalysis(outcome = "RR", data = perioOxy, mc = 0.8, beta = 0.2)
ma$ris
# Or by using the two functions in sequence
ma <- metaanalysis(outcome = "RR", data = perioOxy)
ris(outcome = "RR", mc = 0.8, ma = ma, type = "retrospective", fixed = FALSE,
 beta = 0.2, alpha = 0.05, side = 2)