blindrecalc facilitates the planning of a clinical trial with an internal pilot study and blinded sample size recalculation.
Install the current CRAN version of blindrecalc with:
Or install the development version from GitHub with:
# install.packages("devtools") devtools::install_github("imbi-heidelberg/blindrecalc")
blindrecalc currently supports continuous and binary endpoints for
superiority and non-inferiority test problems. Continuous endpoints are
analyzed using Student’s t-test, binary endpoints are analyzed using the
Chi-squared test for superiority trials and the Farrington-Manning test
for non-inferiority trials. Each design can be defined using a
setupFarringtonManning. For example, to setup a superiority trial with
a continuous endpoint:
library(blindrecalc) design <- setupStudent(alpha = 0.025, beta = 0.2, r = 1, delta = 5)
beta refer to the type 1 and type 2 error rate,
r is the
sample size allocation ratio and
deltais the effect size between the
null and the alternative hypothesis. For a non-inferiority trial with a
shifted t-test, additionally the argument
delta_NI must be specified.
To calculate the sample size for a fixed design, use
n_fix(design, nuisance = c(5, 10, 15)) #>  31.39552 125.58208 282.55967
nuisance refers to the nuisance parameter of the design, which in the
case of the t-test is the common variance of the outcome variable.
To calculate the type 1 error rate of the design using blinded sample
size recalculation, use
toer(design, n1 = c(30, 60, 90), nuisance = 10, recalculation = TRUE) #>  0.0263 0.0271 0.0242
n1 refers to the sample size of the internal pilot study
recalculation = TRUE specifices that the type 1 error rate for a
design with blinded sample size recalculation should be computed.
To compute the power of the design, use
pow(design, n1 = c(30, 60, 90), nuisance = 10, recalculation = TRUE) #>  0.7979 0.7938 0.8067
To calculate the distribution of the total sample sizes use
n_dist(design, n1 = c(30, 60, 90), nuisance = 10) #> n_1 = 30 n_1 = 60 n_1 = 90 #> Min. : 40.0 Min. : 64.0 Min. : 90.0 #> 1st Qu.:109.0 1st Qu.:117.0 1st Qu.:120.0 #> Median :131.0 Median :133.0 Median :133.0 #> Mean :134.2 Mean :133.9 Mean :134.1 #> 3rd Qu.:156.0 3rd Qu.:149.0 3rd Qu.:147.0 #> Max. :305.0 Max. :251.0 Max. :219.0
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