terminaldigits

The package `terminaldigits` implements simulated tests of uniformity and independence for terminal digits. For certain parameters, `terminaldigits` also implements Monte Carlo simulations for type I errors and power for the test of independence. Simulations are run in C++ utilizing Rcpp.

Installation

You can install the development version of `terminaldigits` from GitHub with:

``````# install.packages("devtools")
devtools::install_github("josh-mc/terminaldigits")``````

Usage

In many cases, terminal digits can be assumed to be uniformly distributed and independent of preceding digits. A violation of either of these assumptions may point to a data quality issue.

The following examples are based on a data set taken from the third round of a decoy experiment involving hand-washing purportedly carried out in a number of factories in China. For details, see `decoy` and Yu, Nelson, and Simonsohn (2018).

The `td_uniformity` function tests the assumption of uniformity using Pearson’s chi-squared statistic for goodness-of-fit.

``````library(terminaldigits)

td_uniformity(decoy\$weight, decimals = 2, reps = 1000)
#>
#>  Pearson's chi-squared GOF test for uniformity of terminal digits
#>
#> data:  decoy\$weight
#> Chi-squared = 539.67, p-value = 0.000999``````

The `td_independence` function tests the assumption of independence. The default statistic is again Pearson’s chi-squared statistic but the log-likelihood ratio statistic, the Freeman-Tukey statistic, and the root-mean-square statistic are also available.

``````td_independence(decoy\$weight, decimals = 2, reps = 1000)
#>
#>  Chisq test for independence of terminal digits
#>
#> data:  decoy\$weight
#> Chisq = 6422.4, p-value = 0.000999``````

The `td_test` function is a wrapper for the above two functions. For more details, including a discussion of the `td_simulate` function, see the package introduction vignette.

References

Yu, F., Nelson, L., & Simonsohn, U. (2018, December 5). “In Press at Psychological Science: A New ‘Nudge’ Supported by Implausible Data.” DataColoda 74. http://datacolada.org/74