plotConfidenceSequenceTwoProportions {safestats}

Plot bounds of a safe confidence sequence of the difference or log odds ratio for two proportions against the number of data blocks in two data streams ya and yb.

Description

Plot bounds of a safe confidence sequence of the difference or log odds ratio for two proportions against the number of data blocks in two data streams ya and yb.

Usage

plotConfidenceSequenceTwoProportions(
  ya,
  yb,
  safeDesign,
  differenceMeasure = c("difference", "odds"),
  precision = 100,
  deltaStart = 0.001,
  deltaStop = 3,
  trueDifference = NA
)

Arguments

ya

positive observations/ events per data block in group a: a numeric with integer values between (and including) 0 and na, the number of observations in group a per block.

yb

positive observations/ events per data block in group b: a numeric with integer values between (and including) 0 and nb, the number of observations in group b per block.

safeDesign

a safe test design for two proportions retrieved through designSafeTwoProportions().

differenceMeasure

the difference measure to construct the confidence interval for: one of "difference" and "odds".

precision

precision of the grid to search over for the confidence sequence bounds.

deltaStart

for the odds difference measure: the (absolute value of the) smallest log odds ratio to assess for in- or exclusion in the confidence sequence. Default 0.001.

deltaStop

for the odds difference measure: the (absolute value of the) highest log odds ratio to assess for in- or exclusion in the confidence sequence. Default 3.

trueDifference

true difference or log odds ratio in groups A and B: added to the plot.

Value

no return value; called for its side effects, a plot of the confidence sequence.

Examples

set.seed(39413)
ya <- rbinom(n = 30, size = 1, prob = 0.1)
yb <- rbinom(n = 30, size = 1, prob = 0.8)
balancedSafeDesign <- designSafeTwoProportions(na = 1,
                                               nb = 1,
                                               nBlocksPlan = 30)
plotConfidenceSequenceTwoProportions(ya = ya,
                                     yb = yb,
                                     safeDesign = balancedSafeDesign,
                                     differenceMeasure = "difference",
                                     precision = 15,
                                     trueDifference = 0.7)

#log odds ratio difference measure
plotConfidenceSequenceTwoProportions(ya = ya,
                                     yb = yb,
                                     safeDesign = balancedSafeDesign,
                                     differenceMeasure = "odds",
                                     precision = 15,
                                     deltaStop = 5,
                                     trueDifference = log(36))

#switch ya and yb: observe negative log odds ratio in the data, plot mirrored in x-axis
plotConfidenceSequenceTwoProportions(ya = yb,
                                     yb = ya,
                                     safeDesign = balancedSafeDesign,
                                     differenceMeasure = "odds",
                                     precision = 15,
                                     deltaStop = 5,
                                     trueDifference = -log(36))