Skip to contents

Online fallback procedure for FWER control

online_fallback.Rd

Implements the online fallback procedure of Tian and Ramdas (2021), which guarantees strong FWER control under arbitrary dependence of the p-values.

Usage

online_fallback(
  d,
  alpha = 0.05,
  gammai,
  random = TRUE,
  display_progress = FALSE,
  date.format = "%Y-%m-%d"
)

Arguments

d

Either a vector of p-values, or a dataframe with three columns: an identifier (`id'), date (`date') and p-value (`pval'). If no column of dates is provided, then the p-values are treated as being ordered in sequence, arriving one at a time.

alpha

Overall significance level of the FDR procedure, the default is 0.05.

gammai

Optional vector of \(\gamma_i\). A default is provided as proposed by Javanmard and Montanari (2018), equation 31.

random

Logical. If TRUE (the default), then the order of the p-values in each batch (i.e. those that have exactly the same date) is randomised.

display_progress

Logical. If TRUE prints out a progress bar for the algorithm runtime.

date.format

Optional string giving the format that is used for dates.

Value

out

A dataframe with the original data d (which will be reordered if there are batches and random = TRUE), the LORD-adjusted significance thresholds \(\alpha_i\) and the indicator function of discoveries R. Hypothesis \(i\) is rejected if the \(i\)-th p-value is less than or equal to \(\alpha_i\), in which case R[i] = 1 (otherwise R[i] = 0).

Details

The function takes as its input either a vector of p-values or a dataframe with three columns: an identifier (`id'), date (`date') and p-value (`pval'). The case where p-values arrive in batches corresponds to multiple instances of the same date. If no column of dates is provided, then the p-values are treated as being ordered in sequence, arriving one at a time. Given an overall significance level \(\alpha\), we choose a sequence of non-negative non-increasing numbers \(\gamma_i\) that sum to 1.

The online fallback procedure provides a uniformly more powerful method than Alpha-spending, by saving the significance level of a previous rejection. More specifically, the procedure tests hypothesis \(H_i\) at level $$\alpha_i = \alpha \gamma_i + R_{i-1} \alpha_{i-1}$$ where \(R_i = 1\{p_i \leq \alpha_i\}\) denotes a rejected hypothesis.

Further details of the online fallback procedure can be found in Tian and Ramdas (2021).

References

Tian, J. and Ramdas, A. (2021). Online control of the familywise error rate. Statistical Methods for Medical Research, 30(4):976–993.

Examples

sample.df <- data.frame(
id = c('A15432', 'B90969', 'C18705', 'B49731', 'E99902',
    'C38292', 'A30619', 'D46627', 'E29198', 'A41418',
    'D51456', 'C88669', 'E03673', 'A63155', 'B66033'),
date = as.Date(c(rep('2014-12-01',3),
               rep('2015-09-21',5),
                rep('2016-05-19',2),
                '2016-11-12',
               rep('2017-03-27',4))),
pval = c(2.90e-08, 0.06743, 0.01514, 0.08174, 0.00171,
        3.60e-05, 0.79149, 0.27201, 0.28295, 7.59e-08,
        0.69274, 0.30443, 0.00136, 0.72342, 0.54757))

online_fallback(sample.df, random=FALSE)
#>          pval       alphai R
#> 1  2.9000e-08 0.0026758385 1
#> 2  6.7430e-02 0.0032577488 0
#> 3  1.5140e-02 0.0004956249 0
#> 4  8.1740e-02 0.0004121803 0
#> 5  1.7100e-03 0.0003494435 0
#> 6  3.6000e-05 0.0003022950 1
#> 7  7.9149e-01 0.0005682672 0
#> 8  2.7201e-01 0.0002372613 0
#> 9  2.8295e-01 0.0002140474 0
#> 10 7.5900e-08 0.0001949126 1
#> 11 6.9274e-01 0.0003737922 0
#> 12 3.0443e-01 0.0001652568 0
#> 13 1.3600e-03 0.0001535420 0
#> 14 7.2342e-01 0.0001433627 0
#> 15 5.4757e-01 0.0001344368 0

set.seed(1); online_fallback(sample.df)
#>          pval       alphai R
#> 1  2.9000e-08 0.0026758385 1
#> 2  6.7430e-02 0.0032577488 0
#> 3  1.5140e-02 0.0004956249 0
#> 4  8.1740e-02 0.0004121803 0
#> 5  1.7100e-03 0.0003494435 0
#> 6  2.7201e-01 0.0003022950 0
#> 7  3.6000e-05 0.0002659722 1
#> 8  7.9149e-01 0.0005032335 0
#> 9  7.5900e-08 0.0002140474 1
#> 10 2.8295e-01 0.0004089600 0
#> 11 6.9274e-01 0.0001788796 0
#> 12 7.2342e-01 0.0001652568 0
#> 13 3.0443e-01 0.0001535420 0
#> 14 5.4757e-01 0.0001433627 0
#> 15 1.3600e-03 0.0001344368 0

set.seed(1); online_fallback(sample.df, alpha=0.1)
#>          pval       alphai R
#> 1  2.9000e-08 0.0053516771 1
#> 2  6.7430e-02 0.0065154977 0
#> 3  1.5140e-02 0.0009912499 0
#> 4  8.1740e-02 0.0008243606 0
#> 5  1.7100e-03 0.0006988870 0
#> 6  2.7201e-01 0.0006045900 0
#> 7  3.6000e-05 0.0005319444 1
#> 8  7.9149e-01 0.0010064670 0
#> 9  7.5900e-08 0.0004280949 1
#> 10 2.8295e-01 0.0008179201 0
#> 11 6.9274e-01 0.0003577593 0
#> 12 7.2342e-01 0.0003305137 0
#> 13 3.0443e-01 0.0003070841 0
#> 14 5.4757e-01 0.0002867254 0
#> 15 1.3600e-03 0.0002688736 0